MedWorm.com provides a medical RSS filtering service. Over 6000 RSS medical sources are combined and output via different filters. This feed contains the latest items from the 'FEMS Microbiology Letters' source. Thu, 11 Mar 2010 17:58:54 +0100 http://www.medworm.com/index.php?rid=3353989&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01922.x Comparative genomic studies on several thermophilic archaea and bacteria revealed that a set of coordinated changes are associated with organisms adapted to a higher temperature, among which the dinucleotide composition of genomic DNA, pattern of codon usage and amino acid composition of the proteomes reveal subtle differences between thermophilic and mesophilic organisms. In this context, we have analyzed all tRNA sequences present in the complete genome sequences of 57 organisms belonging to psychrophiles, meophiles, thermophiles and hyperthermophiles. The presence of distinct selective constraints was revealed in the number and distribution of tRNAs and in their folding patterns, which could be correlated with the optimal growth temperature. The tRNA contents of thermophiles were found ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3353989 Thu, 11 Mar 2010 00:00:00 +0100 3353989 http://www.medworm.com/index.php?rid=3346194&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01927.x Three indigenous isolates of Bacillus sphaericus (ISPC-5, ISPC-6 and ISPC-8), along with standard 2362 and 1593 strains, were evaluated for spore viability and mosquitocidal activity. Among these, ISPC-8 was the most viable and virulent isolate, exhibiting a significantly higher total viability count (TVC) and lower LC50 values. The TVC of the standard strains ranged from 4.0 to 9.2 × 108 spores mL[minus]1, whereas it was 1.3 × 109 spores mL[minus]1 for ISPC-8. The LC50 values of ISPC-8, 2362 and 1593 against Culex quinquefasciatus were 0.68 × 103, 1.22 × 103 and 1.85 × 103 spores mL[minus]1, respectively. The ISPC-8 was further assessed for host spectrum and found to be more active against C. quinquefasciatus, followed by Culex tritaeniorhynchus, Aedes albopictus and Aedes aegypti. T... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3346194 Tue, 09 Mar 2010 00:00:00 +0100 3346194 http://www.medworm.com/index.php?rid=3326578&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01928.x Potato scab is a serious plant disease caused by several Streptomyces sp., and effective control methods remain unavailable. Although antagonistic bacteria and phages against potato scab pathogens have been reported, to the best of our knowledge, there is no information about fungi that are antagonistic to the pathogens. The aim of this study was to isolate fungal antagonists, characterize their phylogenetic positions, determine their antagonistic activities against potato scab pathogens, and highlight their potential use as control agents under lower pH conditions. Fifteen fungal stains isolated from potato field soils were found to have antagonistic activity against three well-known potato scab pathogens: Streptomyces scabiei, Streptomyces acidiscabiei, and Streptomyces turgidiscabiei. T... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3326578 Wed, 03 Mar 2010 00:00:00 +0100 3326578 http://www.medworm.com/index.php?rid=3318092&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01926.x Coxiella burnetii is a Gram-negative pleomorphic bacterium and the causative agent of Q fever. During infection, the pathogen survives and replicates within a phagosome-like parasitophorous vacuole while influencing cellular functions throughout the host cell, indicating a capacity for effector protein secretion. Analysis of the C. burnetii (RSA 493 strain) genome sequence indicates that C. burnetii contains genes with homology to the Legionella pneumophila Dot/Icm type IVB secretion system (T4BSS). T4BSSs have only been described in L. pneumophila and C. burnetii, marking it a unique virulence determinate. Characterization of bacterial virulence determinants ranging from autotransporter proteins to diverse secretion systems suggests that polar localization may be a virulence mechanism hal... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3318092 Mon, 01 Mar 2010 00:00:00 +0100 3318092 http://www.medworm.com/index.php?rid=3306351&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01925.x Members of the genus Acanthamoeba are present in diverse environments, from freshwater to soil, and also in humans, causing serious brain and corneal infections. Their life cycle presents two stages: the dividing trophozoite and the quiescent cyst. The structures of these life stages have been studied for many years, and structural data have been used for taxonomy. The ultrastructural work on Acanthamoeba cysts was carried out previously by routine transmission electron microscopy (TEM), a process that requires the use of chemical fixation, a procedure that can cause serious artifacts in the ultrastructure of the studied material. In order to prevent fixation artifacts, we processed Acanthamoeba polyphaga cysts by ultrarapid freezing, followed by freeze-fracturing and deep-etching, in orde... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3306351 Thu, 25 Feb 2010 00:00:00 +0100 3306351 http://www.medworm.com/index.php?rid=3297962&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01903.x Pseudomonas fluorescens BM07 is known to produce cold-induced exobiopolymer, which is mainly composed of water-insoluble hydrophobic polypeptides (up to 85%) and saccharides (8%), by decreasing the culture temperature down to as low as 10 °C. We screened for transposon insertion mutants of P. fluorescens BM07 that were unable to produce the exobiopolymer. Among the eight mutants that showed the deficiency of exobiopolymer and O-lipopolysaccharide, one mutant BM07-59 that had the highest polyhydroxyalkanoates (PHA) production was selected. The transposon inserted gene in BM07-59 was identified as galU. The disruption of the gene galU coded for the putative product, UDP-glucose pyrophosphorylase (GalU), resulted in 1.5-fold more accumulation of PHA compared with the wild-type strain from 70... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3297962 Tue, 23 Feb 2010 00:00:00 +0100 3297962 http://www.medworm.com/index.php?rid=3346195&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01934.x Peroxins are required for protein import into peroxisomes as well as for peroxisome biogenesis and proliferation. Loss-of-function mutations in genes for the RING-finger peroxins Pex2, Pex10 and Pex12 lead to a specific block in meiosis in the ascomycete Podospora anserina. However, loss of protein import into peroxisomes does not result in this meiotic defect. Therefore, it has been suggested that these peroxins have a specific function required for meiosis. To determine whether this role is conserved in other filamentous fungi, we have deleted the gene encoding Pex2 in Aspergillus nidulans. The phenotypes resulting from this deletion are no different from those of previously isolated pex mutants affected in peroxisomal protein import, and viable ascospores are produced in selfed crosses.... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3346195 Mon, 22 Feb 2010 00:00:00 +0100 3346195 http://www.medworm.com/index.php?rid=3346196&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01932.x Bacteriocin produced by Lactobacillus curvatus CWBI-B28wt is not completely effective against Listeria monocytogenes in food models. There is evidence suggesting that bacteriocin-degrading proteolytic enzymes produced by the CWBI-B28wt strain and/or present in the food matrix contribute to this rebound of Listeria growth. To limit this problem, we have partially characterized an approximately 10-kb plasmid responsible for bacteriocin production in L. curvatus CWBI-B28wt. This plasmid was transferred by high-voltage electroporation into a less proteolytic, but technologically competent Lactobacillus strain. When the transformed strain was used as a starter culture in a model food system, a high bacteriocin level was maintained for a longer time than with CWBI-B28wt, and Listeria growth rebo... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3346196 Fri, 19 Feb 2010 00:00:00 +0100 3346196 http://www.medworm.com/index.php?rid=3287376&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01916.x In this study, we developed genetic tools for labeling Gram-negative bacteria in order to visualize them in vitro and in their natural environment without the necessity of antibiotic pressure for maintenance. mcherry was cloned into two broad host-range cloning vectors and a pBK-miniTn7 transposon under the constitutive expression of the tac promoter. The applicability of the different constructs was shown in Escherichia coli, various Pseudomonas spp. and Edwardsiella tarda. The expression of mcherry was qualitatively analyzed by fluorescence microscopy and quantified by fluorometry. The suitability of the constructs for visualizing microbial communities was shown for biofilms formed on glass and tomato roots. In addition, it is shown that mCherry in combination with GFP is a suitable mark... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3287376 Fri, 19 Feb 2010 00:00:00 +0100 3287376 http://www.medworm.com/index.php?rid=3279636&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01915.x In this paper we show that in Schizosaccharomyces pombe, mating-specific cell adhesion is dependent on the exocyst subunit Sec8p, but independent of the exocyst subunit Exo70p. In the absence of Exo70p, the forespore membrane does not develop properly and the leading edge protein Meu14p is abnormally distributed. Additionally, the spindle pole body is aberrant in a significant number of exo70[Delta] asci. In both the sec8-1 and the exo70[Delta] mutants, the development of the spore cell wall is impaired. These results show that different steps of sexual development are differentially regulated by the exocyst and suggest the existence of exocyst subcomplexes with distinct roles in mating. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3279636 Wed, 17 Feb 2010 00:00:00 +0100 3279636 http://www.medworm.com/index.php?rid=3269516&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01914.x Biosynthesis of the highly toxic and carcinogenic aflatoxins in select Aspergillus species from the common intermediate O-methylsterigmatocystin has been postulated to require only the cytochrome P450 monooxygenase, OrdA (AflQ). We now provide evidence that the aryl alcohol dehydrogenase NorA (AflE) encoded by the aflatoxin biosynthetic gene cluster in Aspergillus flavus affects the accumulation of aflatoxins in the final steps of aflatoxin biosynthesis. Mutants with inactive norA produced reduced quantities of aflatoxin B1 (AFB1), but elevated quantities of a new metabolite, deoxyAFB1. To explain this result, we suggest that, in the absence of NorA, the AFB1 reduction product, aflatoxicol, is produced and is readily dehydrated to deoxyAFB1 in the acidic medium, enabling us to observe this... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3269516 Sat, 13 Feb 2010 00:00:00 +0100 3269516 http://www.medworm.com/index.php?rid=3266622&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01905.x In this study, the drrA and drrB operons were disrupted for investigating drug production, self-resistance and regulation. The drrA[ndash]drrB null mutant was highly sensitive to daunorubicin. A 10-fold decrease in drug production was observed in the null mutant compared with the wild-type strain. We propose that the absence of a drug-specific efflux pump increases the intracellular concentration of daunorubicin, which is sensed by the organism to turn down drug production. Quantitative real-time PCR analysis of the mutant showed a drastic reduction in the expression of the key regulator dnrI and polyketide synthase gene dpsA. However, the expression of regulatory genes dnrO and dnrN was increased. Feedback regulation based on the intracellular daunorubicin concentration is discussed. (Sou... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3266622 Fri, 12 Feb 2010 00:00:00 +0100 3266622 http://www.medworm.com/index.php?rid=3262353&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01910.x 1-Aminocyclopropane-1-carboxylate (ACC) deaminase activity was evaluated in the biocontrol and plant growth-promoting fungus Trichoderma asperellum T203. Fungal cultures grown with ACC as the sole nitrogen source showed high enzymatic activity. The enzyme encoding gene (Tas-acdS) was isolated, and an average 3.5-fold induction of the gene by 3 mM ACC was detected by real-time PCR. Escherichia coli bacteria carrying the intron-free cDNA of Tas-acdS cloned into the vector pAlter-EX1 under the control of the tac promoter revealed specific ACC deaminase (ACCD) activity and the ability to promote canola (Brassica napus) root elongation in pouch assays. RNAi silencing of the ACCD gene in T. asperellum showed decreased ability of the mutants to promote root elongation of canola seedlings. These d... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3262353 Thu, 11 Feb 2010 00:00:00 +0100 3262353 http://www.medworm.com/index.php?rid=3262354&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01891.x To examine why we failed in direct sequencing of rRNA gene internal transcribed spacer (ITS) in Pleurotus nebrodensis, we obtained monokaryons of P. nebrodensis (00489 and 00491) using a protoplast monokaryonization technique. PCR products of ITS amplifications were sequenced. There was a base pair insertion/deletion difference between the two nuclei of P. nebrodensis that led to failure in direct sequencing. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3262354 Wed, 10 Feb 2010 00:00:00 +0100 3262354 http://www.medworm.com/index.php?rid=3254087&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01906.x The KdpD/KdpE two-component system of Escherichia coli activates the expression of the kdpFABC operon encoding the high-affinity K+ uptake system KdpFABC in response to K+ limitation or salt stress. Earlier, it was proposed that the histidine kinase KdpD is a turgor sensor; recent studies suggest that KdpD integrates three chemical stimuli from the cytoplasm. The histidine kinase KdpD contains several structural features and subdomains that are important for stimulus perception, modulation of the kinase to phosphatase ratio, and signaling. The response regulator KdpE receives the phosphoryl group from KdpD and induces kdpFABC transcription. The three-dimensional structure of the receiver domain was resolved, providing insights into the activation mechanism of this transcriptional regulator... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254087 Tue, 09 Feb 2010 00:00:00 +0100 3254087 http://www.medworm.com/index.php?rid=3246706&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01907.x Random mutagenesis has been used to identify the target DNA sites for the MalI repressor at the divergent Escherichia coli K-12 malX-malI promoters. The malX promoter is repressed by MalI binding to a DNA site located from position [minus]24 to position [minus]9, upstream of the malX promoter transcript start. The malI promoter is repressed by MalI binding from position +3 to position +18, downstream of the malI transcript start. MalI binding at the malI promoter target is not required for repression of the malX promoter. Similarly, MalI binding at the malX promoter target is not required for repression of the malI. Although the malX and malI promoters are regulated by a single DNA site for cyclic AMP receptor protein, they function independently and each is repressed by MalI binding to a ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3246706 Sat, 06 Feb 2010 00:00:00 +0100 3246706 http://www.medworm.com/index.php?rid=3326579&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01921.x The Escherichia coli arginine repressor (ArgR) is an l-arginine-dependent DNA-binding protein that controls the expression of the arginine biosynthetic genes and is required as an accessory factor for Xer site-specific recombination at cer and related recombination sites in plasmids. We used the technique of pentapeptide scanning mutagenesis to isolate a series of ArgR mutants that were considerably reduced in cer recombination, but were still able to repress an argA∷lacZ fusion. DNA sequence analysis showed that all of the mutants mapped to the same nucleotide, resulting in a five amino acid insertion between residues 149 and 150 of ArgR, corresponding to the end of the [alpha]6 helix. A truncated ArgR containing a stop codon at residue 150 displayed the same phenotype as the prote... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3326579 Fri, 05 Feb 2010 00:00:00 +0100 3326579 http://www.medworm.com/index.php?rid=3318093&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01919.x Streptococcus iniae is a major pathogen of fish, causing considerable economic losses in Israel, the United States and the Far East. Containment of mortalities through vaccination was recently compromised due to the emergence of novel vaccine-escape strains that are distinguished from previous strains by their ability to produce large amounts of extracellular polysaccharide (EPS) that is released to the medium. In vitro and in vivo data now indicate that the EPS is a major virulence factor, capable of triggering the proinflammatory cytokine machinery and inducing mortality of fish. Streptococcus iniae EPS might therefore be considered to be responsible for sepsis and death just as lipopolysaccharide is for Gram-negative pathogens. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3318093 Wed, 03 Feb 2010 00:00:00 +0100 3318093 http://www.medworm.com/index.php?rid=3306352&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01920.x Fuel-contaminated soils from Station Nord (St. Nord) in Greenland were sampled with the aim of assessing the intrinsic attenuation potential by quantifying the presence and activity of degradative microbial populations using phenanthrene as a model compound. Mineralization of [14C]phenanthrene to 14CO2 was measured in contaminated soils at temperatures down to 0 °C and sizable naphthalene-, undecane-, biphenyl- and phenanthrene-degrading populations were measured by microplate-based most-probable-number analysis. Cloning and 16S rRNA gene sequencing, focused on the dominant phenanthrene-degrading bacteria, revealed strains related to bacteria previously found in cold and contaminated environments. Overall, we provide evidence for the presence and potential activity of phenanthrene-degradi... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3306352 Wed, 03 Feb 2010 00:00:00 +0100 3306352 http://www.medworm.com/index.php?rid=3227338&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01889.x Tenacibaculum maritimum (formerly Flexibacter maritimus) is a filamentous, biofilm-forming member of the Cytophaga[ndash]Flavobacterium[ndash]Bacteroides group (or Bacteroidetes), which causes the widely distributed marine fish disease tenacibaculosis. A search for N-acylhomoserine lactones (AHLs) quorum-sensing (QS) signals in the culture media of nine representative strains of this species using different biosensor strains revealed the presence of short-type AHL activity in all of them. N-butyryl-l-homoserine lactone (C4-HSL) was identified in T. maritimum NCIMB2154T by LC-MS. A degradation activity for long-acyl AHLs (C10-HSL) was subsequently demonstrated in T. maritimum NCIMB2154T. The acidification of the culture medium after degradation did not allow the recovery of C10-HSL, which i... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3227338 Mon, 01 Feb 2010 00:00:00 +0100 3227338 http://www.medworm.com/index.php?rid=3227337&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01896.x Adenylate cyclase-hemolysin toxin (CyaA) produced from the human respiratory tract pathogen Bordetella pertussis requires fatty-acyl modification by CyaC-acyltransferase to become an active toxin. Previously, the recombinant CyaA pore-forming (CyaA-PF) fragment expressed in Escherichia coli was shown to be hemolytically active upon palmitoylation in vivo by cosynthesized CyaC. Here, the 21-kDa CyaC enzyme separately expressed in E. coli as an inclusion body was solubilized in 8 M urea and successfully refolded into an enzymatically active monomer. In addition to the capability of activating CyaA-PF in vitro, CyaC showed esterase activity against p-nitrophenyl acetate (pNPA) and p-nitrophenyl palmitate (pNPP), with preferential hydrolysis toward pNPP when compared with chymotrypsin. A homol... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3227337 Mon, 01 Feb 2010 00:00:00 +0100 3227337 http://www.medworm.com/index.php?rid=3297963&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01918.x In this study, we found that EAP and Nptase also play a role in biofilm formation under iron-replete conditions in the presence of human serum. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3297963 Fri, 29 Jan 2010 00:00:00 +0100 3297963 http://www.medworm.com/index.php?rid=3306353&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01912.x The pathogenicity of smut fungi is initiated by the fusion of two compatible saprotrophic yeasts that give rise to the formation of dikaryotic pathogenic hyphae. It has been described in the literature that complementation assays of auxotrophic yeasts of Ustilago maydis have allowed the isolation of diploid strains that are solopathogenic, i.e. pathogenic in the absence of mating. The occurrence of such strains from germinating teliospores was not investigated. We evaluated the ability of teliospores to generate solopathogenic strains in three species of smut fungi: Sporisorium reilianum f.sp. zeae, U. maydis and Moesziomyces penicillariae. Using an approach based on the stability of pseudohyphae of solopathogenic strains, we isolated the strain SRZS1 from teliospores of S. reilianum. Micr... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3306353 Wed, 27 Jan 2010 00:00:00 +0100 3306353 http://www.medworm.com/index.php?rid=3269518&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01911.x 16S rRNA gene-based analysis of rumen Prevotella was carried out to estimate the diversity and diet specificity of bacteria belonging to this genus. Total DNA was extracted from the rumen digesta of three sheep fed two diets with different hay-to-concentrate ratios (10 : 1 and 1 : 2). Real-time PCR quantification of Prevotella revealed that the relative abundance of this genus in the total rumen bacteria was up to 19.7%, while the representative species Prevotella bryantii and Prevotella ruminicola accounted for only 0.6% and 3.8%, respectively. Denaturing gradient gel electrophoresis analysis for Prevotella revealed shifts in the community composition with the diet. Analysis of 16S rRNA gene clone libraries showed significant differences (P=0.001) between clones detected from the sheep on... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3269518 Wed, 27 Jan 2010 00:00:00 +0100 3269518 http://www.medworm.com/index.php?rid=3269517&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01913.x Streptococcus pneumoniae, the leading etiological agent of pneumonia, shares a high degree of DNA sequence homology with the viridans group of streptococci. The clinical and pathological manifestations may present with different features, and discrimination between S. pneumoniae and its close viridans cocci relatives, such as Streptococcus mitis and Streptococcus oralis, is still quite difficult. The 445-bp sequences of the N-terminal region of rpoA from nine S. pneumoniae, seven S. mitis, ten S. oralis, and two related strains were determined and compared with their respective 16S rRNA gene sequences to establish their usefulness in phylogenetic analysis. Pairwise comparisons of rpoA sequences among the species showed higher rates of evolution with lower similarities (92.3[ndash]100%) tha... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3269517 Wed, 27 Jan 2010 00:00:00 +0100 3269517 http://www.medworm.com/index.php?rid=3211912&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01890.x Aspergillus flavus is one of the most common contaminants that produces aflatoxins in foodstuffs. It is also a human allergen and a pathogen of animals and plants. Aspergillus flavus is included in the Aspergillus section Flavi that comprises 11 closely related species producing different profiles of secondary metabolites. A six-step strategy has been developed that allows identification of nine of the 11 species. First, three real-time PCR reactions allowed us to discriminate four groups within the section: (1) A. flavus/Aspergillus oryzae/Aspergillus minisclerotigenes/Aspergillus parvisclerotigenus; (2) Aspergillus parasiticus/Aspergillus sojae/Aspergillus arachidicola; (3) Aspergillus tamarii/Aspergillus bombycis/Aspergillus pseudotamarii; and (4) Aspergillus nomius. Secondly, random am... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3211912 Wed, 27 Jan 2010 00:00:00 +0100 3211912 http://www.medworm.com/index.php?rid=3200214&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01884.x Recently, a cyclic AMP receptor protein homologue, GlxR, was reported to bind to the upstream regions of several genes involved in the regulation of diverse physiological processes in Corynebacterium glutamicum. However, the function of GlxR has not yet been explored in C. glutamicum in vivo using a glxR deletion mutant. Therefore, this study examines the role of GlxR as a repressor in glyoxylate bypass and carbon catabolite repression (CCR) using a deletion mutant. The disruption of glxR resulted in a severe growth defect, but growth was restored by complementation with the glxR and crp genes from C. glutamicum and Streptomyces coelicolor, respectively. The production of isocitrate lyase (ICL) and malate synthase (MS) was significantly increased in the glxR mutant. The specific activities... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3200214 Sat, 23 Jan 2010 00:00:00 +0100 3200214 http://www.medworm.com/index.php?rid=3346197&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01908.x A bacteriophage [Phi]BP infecting Paenibacillus polymyxa CCM 7400 was isolated from culture lysate. Electron microscopy of lysate samples revealed the presence of bacteriophage particles with polyhedral heads 56 nm in diameter and flexible noncontractile tails 144 nm in length. The profile of [Phi]BP structural proteins resembles that of other bacteriophages. The [Phi]BP genome consists of double-stranded DNA of 43-kbp size. Homology search of sequenced DNA fragments from EcoRI digest revealed regions with significant similarity to other known bacteriophage genes. Regions similar to phage terminase genes were identified within the 1.2-kbp fragment. Three lytic genes, two holin genes and one endolysin gene were identified within the 2.5-kbp fragment. We tested the isolates of P. polymyxa CC... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3346197 Fri, 22 Jan 2010 00:00:00 +0100 3346197 http://www.medworm.com/index.php?rid=3279637&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01909.x We examined the variation and relationships between pathogenicity and a microsatellite-based haplotype in 79 Tunisian Rhynchosporium secalis isolates that were collected from the most commonly cultivated barley populations in Tunisia, Rihane cv. and local landraces, with the goal of finding genes that might be used to monitor resistance to scald. Isolates could be classified into three distinct virulence groups based on artificial inoculation of 19 differential cultivars with known scald resistance genes. The resistance gene BRR2 carried by the Astrix differential cultivar appeared to be the most effective in Tunisia. Pathotypes sampled from the Rihane host were more virulent than those sampled from local barley landraces. Because some differential cultivars that carried the same resistanc... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3279637 Fri, 22 Jan 2010 00:00:00 +0100 3279637 http://www.medworm.com/index.php?rid=3193344&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01893.x Mycoplasmas often contaminate cultured cells, leading to alterations in cellular gene expression, protein synthesis, signal transduction and metabolic pathways. Mycoplasmal contamination is often unnoticed, so that mycoplasma-induced alterations in cell functions may not be appreciated, unless specifically studied. Here, we show for the first time that contamination of SH-SY5Y cells by Mycoplasma hyorhinis leads to increased levels of calpastatin (the endogenous inhibitor of the Ca2+-dependent protease calpain), resulting in inhibition of Ca2+-induced calpain activation and inhibition of calpain-promoted proteolysis in the mycoplasmal-infected cells. Calpain activity is recovered upon calpastatin removal from extracts of contaminated cells. The calpain[ndash]calpastatin system has been imp... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3193344 Thu, 21 Jan 2010 00:00:00 +0100 3193344 http://www.medworm.com/index.php?rid=3254088&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01904.x Salmonella enterica represents a major human and animal pathogen. Many S. enterica genomes have been completed and many more genome sequencing projects are underway, constituting an excellent resource for comparative genome analysis studies leading to a better understanding of bacterial evolution and pathogenesis. Salmonella enterica serovar Typhimurium and Typhi are the best-characterized serovars, with the first being involved in localized gastroenteritis in many hosts and the latter causing a systemic human-specific disease. Here, we summarize the major genetic differences between the two different serovars. We detail the divergent repertoires of the virulence factors responsible for the pathogenesis of the organisms and that ultimately result in the distinct clinical outcomes of infect... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254088 Wed, 20 Jan 2010 00:00:00 +0100 3254088 http://www.medworm.com/index.php?rid=3193345&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01888.x Bacillus thuringiensis is a gram-positive spore-forming bacterium that can accumulate poly(3-hydroxybutyrate) (PHB) as a carbon and energy storage substance in response to nutritional stress. The regulatory mechanism for PHB biosynthesis in B. thuringiensis and diverse Bacillus species is still poorly understood. We now report that disruption of the sigH gene or the gene encoding the master sporulation transcription factor Spo0A severely impaired PHB accumulation in B. thuringiensis. Complementation of the spo0A mutation with the spo0A gene restored PHB accumulation. We have found that the requirement of Spo0A for PHB accumulation is independent of the transition state regulator AbrB and of loss of sporulation ability. We also show that Spo0A is required for the expression of three genes i... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3193345 Wed, 20 Jan 2010 00:00:00 +0100 3193345 http://www.medworm.com/index.php?rid=3254091&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01901.x The Pectobacterium atrosepticum strain SCRI1043 genome contains two complete prophage sequences. One, ECA41, is Mu-like and is able to integrate into, and excise from, various genomic locations. The other, ECA29, is a P2 family prophage, and is also able to excise from the genome. Excision of both prophages is rare and we were unable to induce lysis of cultures. Deletion of the entire prophages, both separately and in combination, did not affect the growth rate or the secretion of plant cell wall-degrading enzymes, but swimming motility was decreased. The virulence of prophage deletion strains in the potato host was decreased. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254091 Mon, 18 Jan 2010 00:00:00 +0100 3254091 http://www.medworm.com/index.php?rid=3254090&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01902.x This study reports the first successful application of real-time PCR for the detection of Mycobacterium ulcerans, the causative agent of Buruli ulcer (BU), in Ghana, a BU-endemic country. Environmental samples and organs of small mammals were analyzed. The real-time PCR assays confirmed the presence of M. ulcerans in a water sample collected in a BU-endemic village in the Ashanti Region. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254090 Mon, 18 Jan 2010 00:00:00 +0100 3254090 http://www.medworm.com/index.php?rid=3178555&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01892.x Xanthomonas campestris pv. campestris (Xcc) is the causal agent of black rot disease in cruciferous plants. The synthesis of known virulence factors in this organism, such as extracellular enzymes and biofilm, is strictly regulated in response to environmental stimuli. Two-component signal transduction systems sense environmental signals and alter bacterial behavior by regulating gene expression. Here, we identified a response regulator, VemR, that regulates Xcc pathogenesis. The vemR gene encodes an atypical response regulator that only contains a receiver domain. Deletion of vemR resulted in decreased virulence, exopolysaccharide production and motility of Xcc. The vemR gene is located in an operon flanked by genes fleQ and rpoN2. Genetic analysis indicated that deletion of fleQ does not... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3178555 Sat, 16 Jan 2010 00:00:00 +0100 3178555 http://www.medworm.com/index.php?rid=3175451&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01894.x Type IV pili are crucial for the virulence of Neisseria meningitidis. PilC proteins belong to the complex protein machinery required for pili biosynthesis. The expression of the pilC1 gene is known to be induced during host cell contact and to be tightly controlled through four promoters, two transcription factors and a two-component signal transduction system. By screening of an insertional-mutant library, we identified a novel regulatory protein, i.e. NMA1805, involved in the pilC1 complex regulation. Increased transcription of gene NMA1805 was shown to result in augmented expression of the pilC1 gene, whereas abrogated expression of gene NMA1805 was associated with an absence of pilC1 induction upon contact with host cells. Moreover, we demonstrated that the NMA1805 gene displayed two p... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3175451 Fri, 15 Jan 2010 00:00:00 +0100 3175451 http://www.medworm.com/index.php?rid=3166740&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01875.x An antibacterial compound, S07-2, was purified to homogeneity by hydrophobic interaction, anion exchange, C18 reverse-phase and HS PEG HPLC. The molecular mass of S07-2 was 905.6 Da as determined by MS. The S07-2 compound was resistant to high temperatures (up to 100 °C) and could withstand a wide range of pH from 3 to 10. In addition, its antibacterial activity was preserved after treatment with proteases. Biochemical characterization revealed its cyclic peptide structure. This compound showed a bactericidal effect against important food-spoilage bacteria and food-borne pathogens including Listeria monocytogenes and Enterococcus faecalis with lethal concentration values of 62.5 [mu]g mL[minus]1 and against Salmonella enteritidis at a concentration of 31.25 [mu]g mL[minus]1. However, no c... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3166740 Wed, 13 Jan 2010 00:00:00 +0100 3166740 http://www.medworm.com/index.php?rid=3246707&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01900.x The plasmid pAL1 of Arthrobacter nitroguajacolicus Rü61a is a linear replicon, characterized by inverted terminal repeats and terminal proteins (TPs) covalently bound to its 5'-ends. Previous sequence analysis and predictions of possible secondary structures formed by telomeric 3'-overhangs indicated significant differences of the 'left' and 'right' telomere of pAL1, raising the question of whether each terminus is recognized by a specific protein. The genes pAL1.102 and pAL1.103, located close to a terminus, code for possible DNA-binding proteins; however, only the pORF102 protein encoded by pAL1.102 shows a weak similarity to known TPs of Streptomyces linear replicons. pORF102, purified from recombinant A. nitroguajacolicus Rü61a as a fusion with maltose-binding protein (MBP), was spec... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3246707 Tue, 12 Jan 2010 00:00:00 +0100 3246707 http://www.medworm.com/index.php?rid=3266623&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01899.x Mycinamicin, a 16-membered macrolide antibiotic produced by Micromonospora griseorubida, comprises a macrolactone and two deoxysugars: desosamine and mycinose. Mycinose is synthesized through two modification steps: the methylation of 6-deoxyallose in mycinamicin VI and of javose in mycinamicin III. To confirm the role of mycE and mycF genes in mycinamicin biosynthesis in M. griseorubida, disruption mutants of mycE and mycF were constructed by disruption plasmids containing attB in the disruption cassette FRT-neo-oriT-FRT-attB for the integration of [phi]C31-derivative vector plasmids; the disruption mutants were complemented through the integration of pSET152 derivatives containing intact mycE or mycF into the artificially inserted attB site. These disruption mutants did not produce mycin... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3266623 Mon, 11 Jan 2010 00:00:00 +0100 3266623 http://www.medworm.com/index.php?rid=3254092&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01897.x In conclusion, we provide new information about the chemical structures that inhibit P. aeruginosa virulence. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254092 Mon, 11 Jan 2010 00:00:00 +0100 3254092 http://www.medworm.com/index.php?rid=3254089&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01898.x In conclusion, we have shown that dietary fibre from almond skins altered the composition of gut bacteria and almond skins resulting from industrial blanching could be used as potential prebiotics. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3254089 Mon, 11 Jan 2010 00:00:00 +0100 3254089 http://www.medworm.com/index.php?rid=3156268&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01878.x In this study, we showed that FimH also binds to HBMEC, independent of mannose, and identified ATP synthase [beta]-subunit and actin proteins from the surface biotinylated HBMEC as the mannose-insensitive binding targets for FimH. Co-immunoprecipitation experiments in the presence of [alpha]-methyl mannose verified the binding of FimH to ATP synthase [beta]-subunit of HBMEC. ATP synthase [beta]-subunit antibody decreased E. coli K1 binding to HBMEC in the presence of [alpha]-methyl mannose. Taken together, these findings demonstrate that FimH of E. coli K1 binds to HBMEC in both mannose-sensitive and -insensitive manner. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3156268 Sat, 09 Jan 2010 00:00:00 +0100 3156268 http://www.medworm.com/index.php?rid=3246708&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2010.01895.x Although the biosynthesis of oxalic acid is known to occur in a number of bacteria, the mechanism(s) regulating its production remains largely unknown. To date, there is no report on the identification of an oxalic acid biosynthetic pathway gene from bacteria. In an attempt to identify such a gene(s), a mutant screen was conducted using the simple oxalic acid-producing phytopathogenic bacterium, Burkholderia glumae. Four mutants that failed to produce oxalic acid were isolated from a transposon-mutagenized B. glumae library and named Burkholderia oxalate defective (Bod)1. DNA sequence analysis revealed that each mutant contained an insertion event at different sites in the same ORF, which we referred to as the oxalate biosynthetic component (obc)A locus. Complementation of the Bod1 mutant ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3246708 Fri, 08 Jan 2010 00:00:00 +0100 3246708 http://www.medworm.com/index.php?rid=3178556&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01887.x The mechanism underlying the killing activity of Lactobacillus strains against bacterial pathogens appears to be multifactorial. Here, we investigate the respective contributions of hydrogen peroxide and lactic acid in killing bacterial pathogens associated with the human vagina, urinary tract or intestine by two hydrogen peroxide-producing strains. In co-culture, the human intestinal strain Lactobacillus johnsonii NCC933 and human vaginal strain Lactobacillus gasseri KS120.1 strains killed enteric Salmonella enterica serovar Typhimurium SL1344, vaginal Gardnerella vaginalis DSM 4944 and urinary tract Escherichia coli CFT073 pathogens. The cell-free culture supernatants (CFCSs) produced the same reduction in SL1344, DSM 4944 and CFT073 viability, whereas isolated bacteria had no effect. Th... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3178556 Thu, 24 Dec 2009 00:00:00 +0100 3178556 http://www.medworm.com/index.php?rid=3118584&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01876.x Nitrate reduction is believed to be vital for the survival of tubercle bacteria under hypoxic/anaerobic conditions that are thought to prevail within granulomas. Nitrate reductase activity is rapidly induced in Mycobacterium tuberculosis (M. tb) under hypoxic conditions and is attributed to the induced expression of the nitrate/nitrite transporter gene, narK2. By contrast, Mycobacterium bovis (M. bovis) and M. bovis BCG (BCG) do not support the hypoxic induction of either nitrate reductase activity or narK2. Here, we show that the induction defect in the narK2X operon in M. bovis and BCG is caused by a [minus]6T/C single nucleotide polymorphism (SNP) in the [minus]10 promoter element essential for narK2X promoter activity. Complementation of M. bovis with both narGHJI and narK2X genes from... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3118584 Thu, 24 Dec 2009 00:00:00 +0100 3118584 http://www.medworm.com/index.php?rid=3110862&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01877.x Eradication of Helicobacter pylori with traditional therapy often fails in clinical treatment. As a result, a novel efficacious therapeutic agent is strongly needed. Allitridi, a proprietary garlic derivative, has been successfully used to treat both systemic fungal and bacterial infections in China. Our previous study has shown a dose-dependent inhibitory effect of allitridi on H. pylori growth. However, the antibacterial mode of action of allitridi is still unclear. Proteomic analysis was used to study the global protein alterations induced by allitridi. A total of 21 protein spots were identified to be differentially expressed. Our results indicated that the bacteriostatic mechanism of allitridi in H. pylori can be attributed to its multitarget inhibitory effects in energy metabolism an... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110862 Tue, 22 Dec 2009 00:00:00 +0100 3110862 http://www.medworm.com/index.php?rid=3166741&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01885.x Xylella fastidiosa causes a serious Pierce's disease (PD) in grapevine. Xylella fastidiosa cells from a PD strain were grown in a pure xylem fluid of a susceptible grapevine cultivar vs. xylem fluid from citrus, which is not a host for this strain of X. fastidiosa. When grown in grapevine xylem fluid, cells of the PD strain formed clumps and biofilm formed to a greater extent than in citrus xylem fluid, although the PD strain did grow in xylem fluid of three citrus varieties. The differential expression of selected genes of a PD X. fastidiosa strain cultured in the two xylem fluids was analyzed using a DNA macroarray. Compared with citrus xylem fluid, grapevine xylem fluid stimulated the expression of X. fastidiosa genes involved in virulence regulation, such as gacA, algU, xrvA, and hsq, ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3166741 Sat, 19 Dec 2009 00:00:00 +0100 3166741 http://www.medworm.com/index.php?rid=3156269&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01886.x During the course of our screening program to isolate isoprenoids from marine Actinobacteria, 523 actinobacterial strains were isolated from 18 marine sponges, a tunicate, and two marine sediments. These strains belonged to 21 different genera, but most were members of Streptomyces, Nocardia, Rhodococcus, and Micromonospora. Some Actinobacteria have been reported to use the mevalonate pathway for the production of isoprenoids as secondary metabolites. Therefore, we investigated whether these strains possessed the 3-hydroxyl-3-methylglutaryl coenzyme A reductase (hmgr) gene, which indicates the presence of the mevalonate pathway. As a result, six strains belonging to the genera Streptomyces (SpC080624SC-11, SpA080624GE-02, and Sp080513GE-23), Nocardia (Sp080513SC-18), and Micromonospora (Se... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3156269 Sat, 19 Dec 2009 00:00:00 +0100 3156269 http://www.medworm.com/index.php?rid=3166743&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01882.x Bacillus sp. strain CS93, which was previously isolated from Pozol, was previously shown to produce iturin A, bacilysin and chlorotetaine. To investigate the biosynthetic mechanism of chlorotetaine production, the bac genes were amplified from genomic DNA of Bacillus sp. CS93 by PCR and sequenced. The genes bacABCDE were determined, but no gene that might code for a halogenating enzyme was detected either within the gene cluster or in the flanking sequences. Following further analysis of culture supernatants that were active against bacteria by liquid chromatography-MS, it was not possible to detect bacilysin/chlorotetaine. However, in methanolic fractions containing antibacterial activity, molecular ions characteristic of surfactins and fengycin were detectable by electrospray MS. Using p... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3166743 Fri, 18 Dec 2009 00:00:00 +0100 3166743 http://www.medworm.com/index.php?rid=3166742&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01883.x We report here that the V75I substitution in the [alpha]-subunit of Nif2 showed greatly impaired acetylene reduction and reduced levels of 15N2 fixation but had similar hydrogen production rates as the wild-type enzyme under argon. Another mutant containing a substitution in the [alpha]-subunit, V76I, would result in a decrease in the size of the putative gas channel of nitrogenase and, thus, was hypothesized to affect substrate selectivity of nitrogenase. However, this substitution had no effect on the enzyme selectivity, suggesting that access by gases to the active site through this putative gas channel is not limited by the increased size of the amino acid side chain in the [alpha]-subunit, V76I substitution. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3166742 Fri, 18 Dec 2009 00:00:00 +0100 3166742 http://www.medworm.com/index.php?rid=3100206&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01869.x We demonstrated that a yeast deletion mutant in IPT1 and SKN1, encoding proteins involved in the biosynthesis of mannosyldiinositolphosphoryl ceramides, is characterized by increased autophagy and DNA fragmentation upon nitrogen (N) starvation as compared with the single deletion mutants or wild type (WT). Apoptotic features were not significantly different between single and double deletion mutants upon N starvation, pointing to increased autophagy in the double [Delta]ipt1[Delta]skn1 deletion mutant independent of apoptosis. We observed increased basal levels of phytosphingosine in membranes of the double [Delta]ipt1[Delta]skn1 deletion mutant as compared with the single deletion mutants or WT. These data point to a negative regulation of autophagy by both Ipt1 and Skn1 in yeast, with a ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3100206 Fri, 18 Dec 2009 00:00:00 +0100 3100206 http://www.medworm.com/index.php?rid=3193346&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01881.x The function of sialic acids in the biology of bacterial pathogens is reflected by the diverse range of solute transporters that can recognize these sugar acids. Here, we use an Escherichia coli[Delta]nanT strain to characterize the function of known and proposed bacterial sialic acid transporters. We discover that the STM1128 gene from Salmonella enterica serovar Typhimurium, which encodes a member of the sodium solute symporter family, is able to restore growth on sialic acid to the [Delta]nanT strain and is able to transport [14C]-sialic acid. Using the [Delta]nanT genetic background, we performed a direct in vivo comparison of the transport properties of the STM1128 protein with those of sialic acid transporters of the major facilitator superfamily and tripartite ATP-independent peripl... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3193346 Thu, 17 Dec 2009 00:00:00 +0100 3193346 http://www.medworm.com/index.php?rid=3166744&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01880.x The lignin peroxidase (LiP) from Trametes cervina was cloned, characterized, and identified as a novel fungal peroxidase. The sequence of T. cervina LiP encodes the essential amino acids for shaping the heme cavity and calcium-binding sites, which are conserved in plant and fungal peroxidases. However, a sequence homology analysis showed that T. cervina LiP has two unique features: it lacks the conserved tryptophan residue corresponding to the substrate-oxidation site (Trp171) of Phanerochaete chrysosporium LiP and it has a tyrosine residue (Tyr181) that has never been reported in other lignin peroxidases. A tertiary model of T. cervina LiP showed that Tyr181 sterically adjacent to the 6-propionate group of heme is surrounded by acidic amino acids and is exposed to the exterior. These attr... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3166744 Thu, 17 Dec 2009 00:00:00 +0100 3166744 http://www.medworm.com/index.php?rid=3096359&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01856.x Chronological analysis of 125 Vibrio cholerae O139 strains isolated during 1993[ndash]2005 in Kolkata revealed the prevalence of two new genotypes of cholera toxin (CT) and novel combinations of ctxB and rstR alleles resulting in variant CTX prophages. One of the new genotypes of ctxB, which first appeared in 1996 with the re-emerged V. cholerae O139 strains that had CTX Calcutta phage, was designated as genotype 4. In 1998, another new genotype, designated as genotype 5, was detected that prevailed mostly in CTX phages with El Tor rstR. The prototype El Tor CTX phage with genotype 3 gradually disappeared in O139, and since 2002 the predominant CTX prophages in O139 are Calcutta phages with genotype 4 and El Tor phages with genotype 5. Results showed that V. cholerae O139 strains of Kolkat... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3096359 Thu, 17 Dec 2009 00:00:00 +0100 3096359 http://www.medworm.com/index.php?rid=3092401&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01863.x Penicillin-binding protein (PBP) 5 plays a critical role in maintaining normal cellular morphology in mutants of Escherichia coli lacking multiple PBPs. The most closely related homologue, PBP 6, is 65% identical to PBP 5, but is unable to substitute for PBP 5 in returning these mutants to their wild-type shape. The relevant differences between PBPs 5 and 6 are localized in a 20-amino acid stretch of domain I in these proteins, which includes the canonical KTG motif at the active site. We determined how these differences affected the enzymatic properties of PBPs 5 and 6 toward [beta]-lactam binding and the binding and hydrolysis of two peptide substrates. We also investigated the enzymatic properties of recombinant fusion proteins in which active site segments were swapped between PBPs 5 a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3092401 Wed, 16 Dec 2009 00:00:00 +0100 3092401 http://www.medworm.com/index.php?rid=3082186&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01851.x Genetic transformation is an indispensable tool for basic fungal research, as well as a useful technique for directed improvement of industrial strains. Here we describe a simple and reproducible transformation system for the filamentous fungus Hypocrea jecorina. The system is based on hxk1 (encoding hexokinase) as selectable marker, a hexokinase-negative strain and d-mannitol, which is used as selective carbon source and osmotic stabilizer. Following transformation with the hxk1 gene, the obtained transformants were able to grow on d-mannitol as sole carbon source. Transformation efficiency achieved using d-mannitol as carbon source and osmotic stabilizer was roughly five times higher than that using d-sorbitol. The utility of this system was further demonstrated by transformation of H. j... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3082186 Sat, 12 Dec 2009 00:00:00 +0100 3082186 http://www.medworm.com/index.php?rid=3156270&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01879.x l-Alanyl-l-glutamine (Ala-Gln) is a clinically and nutritionally important dipeptide. We have already shown a novel method for the fermentative production of Ala-Gln using an Escherichia coli strain expressing l-amino acid [alpha]-ligase (Lal), which catalyzes the formation of dipeptides by combining two amino acids. In the course of Ala-Gln-producing strain development, it was revealed that Lal expression caused growth inhibition. We also found that the addition of some dipeptides, including Ala-Gln, inhibited the growth of a multiple peptidase-deficient strain. To further increase the productivity by overcoming the inhibitory effect of dipeptides, we focused on dipeptide transport systems. The four genes (bcr, norE, ydeE and yeeO) were selected from 34 genes encoding a multidrug-efflux t... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3156270 Thu, 10 Dec 2009 00:00:00 +0100 3156270 http://www.medworm.com/index.php?rid=3075094&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01865.x Bacillus sphaericus produces a mosquito-larvicidal binary toxin composed of BinB and BinA subunits. BinA is important for toxicity, whereas BinB acts as a specific receptor-binding component. To study the functional significance of two regions that are only present in BinB, four block mutations and two single mutations were initially introduced: 111YLD113[rarr]111AAA113, 115NNH117[rarr]115AAA117, 143GEQ145[rarr]143AAA145, 147FQFY150[rarr]147AAAA150, N114A and F146A. Only the replacements at 147FQFY150 resulted in a total loss of toxicity to Culex quinquefasciatus larvae. Further single alanine substitutions in this region, F147A, Q148A, F149A and Y150A, were introduced to identify residues playing a critical role in mosquito-larvicidal activity. Larvicidal activity assays revealed that onl... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3075094 Thu, 10 Dec 2009 00:00:00 +0100 3075094 http://www.medworm.com/index.php?rid=3070779&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01860.x A Caulobacter crescentus rho∷Tn5 mutant strain presenting a partially functional transcription termination factor Rho is highly sensitive to hydrogen peroxide in both exponential and stationary phases. The mutant was shown to be permanently under oxidative stress, based on fluorophore oxidation, and also to be sensitive to tert-butyl hydroperoxide and paraquat. However, the results showed that the activities of superoxide dismutases CuZnSOD and FeSOD and the alkylhydroperoxide reductase ahpC mRNA levels in the rho mutant were comparable to the wild-type control in the exponential and stationary phases. In contrast, the KatG catalase activity of the rho mutant strain was drastically decreased and did not show the expected increase in the stationary phase compared with the exponential... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3070779 Wed, 09 Dec 2009 00:00:00 +0100 3070779 http://www.medworm.com/index.php?rid=3066642&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01862.x This study reports the first isolation of an FNT family member. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3066642 Tue, 08 Dec 2009 00:00:00 +0100 3066642 http://www.medworm.com/index.php?rid=3110865&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01873.x Phosphatidylcholine, the major phospholipid in eukaryotes, is found in rhizobia and in many other bacteria interacting with eukaryotic hosts. Phosphatidylcholine has been shown to be required for a successful interaction of Bradyrhizobium japonicum USDA 110 with soybean roots. Our aim was to study the role of bacterial phosphatidylcholine in the Bradyrhizobium[ndash]peanut (Arachis hypogaea) symbiosis. Phospholipid N-methyltransferase (Pmt) and minor phosphatidylcholine synthase (Pcs) activities were detected in crude extracts of the peanut-nodulating strain Bradyrhizobium sp. SEMIA 6144. Our results suggest that phosphatidylcholine formation in Bradyrhizobium sp. SEMIA 6144 is mainly due to the phospholipid methylation pathway. Southern blot analysis using pmt- and pcs-probes of B. japoni... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110865 Thu, 03 Dec 2009 00:00:00 +0100 3110865 http://www.medworm.com/index.php?rid=3110864&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01874.x A published multiple-locus variable number of tandem-repeats analysis (MLVA) scheme was compared with pulsed-field gel electrophoresis (PFGE) for genotyping of 62 Escherichia coli O26 strains from humans, animals and food. The strains were isolated between 1947 and 2006 in eight countries on three continents and divided into 23 enterohaemorrhagic E. coli (EHEC), 33 enteropathogenic E. coli (EPEC), one enterotoxigenic E. coli (ETEC) and five avirulent strains. ETEC and avirulent E. coli serotyped as O26:H32. EHEC and EPEC O26 strains shared flagellar type H11 and the eae-[beta] gene, and divided into two clonal lineages by their arcA gene sequence and fermentation of rhamnose and dulcitol. The rhamnose/dulcitol-nonfermenting (RDF[minus]), 'arcA allele 1' type comprised 22 EHEC and 15 EPEC s... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110864 Thu, 03 Dec 2009 00:00:00 +0100 3110864 http://www.medworm.com/index.php?rid=3110863&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01871.x Diesel fuel is a common environmental pollutant comprised of a large number of both aromatic and aliphatic hydrocarbons. The microbial degradation of individual hydrocarbons has been well characterized, however, the community dynamics within a system degrading a complex pollutant such as diesel fuel are still poorly understood. The growth capabilities of a diesel-degrading consortium, along with organisms isolated from a contaminated site, were investigated using molecular profiling, isolation, and physiological methods using 10 of the fuel's most abundant constituents as sole carbon sources. The results indicated that the degradation of the fuel's constituents may be shared among the diverse microbial community. Some organisms were capable of growth on the majority of the hydrocarbons tes... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110863 Thu, 03 Dec 2009 00:00:00 +0100 3110863 http://www.medworm.com/index.php?rid=3051866&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01858.x Afipia felis, a Gram-negative alphaproteobacterium, has been implicated as one of the causative agents of cat scratch disease. To identify and begin to examine the virulence traits of this organism, we developed and tested a highly efficient transposon delivery system and a stable plasmid vector expressing green fluorescent protein. The transposome system is based on a Tn5-derived transposon and a phage restriction endonuclease type I inhibitor. Electroporation of this construct produced a library of >2600 mutants, which were screened for flagella biosynthesis mutants using a monoclonal antibody to Afipia flagellin. Insertion loci for two selected mutants were located in the genes for flagellin and flagellin biosynthesis FlhA, confirming the validity of the approach. (Source: FEMS Microbio... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3051866 Thu, 03 Dec 2009 00:00:00 +0100 3051866 http://www.medworm.com/index.php?rid=3110866&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01872.x Berberine, a natural isoquinoline alkaloid found in many medicinal herbs, has been shown to be active against a variety of microbial infections. To examine the potential effects of berberine on Shigella flexneri, a whole-genome DNA microarray was constructed and a transcriptome analysis of the cellular responses of S. flexneri when exposed to berberine chloride (BC) was performed. Our data revealed that BC upregulated a group of genes involved in DNA replication, repair and division. Intriguingly, the expression of many genes related to cell envelope biogenesis was increased. In addition, many genes involved in cell secretion, nucleotide metabolism, translation, fatty acid metabolism and the virulence system were also induced by the drug. However, more genes from the functional classes of ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110866 Wed, 02 Dec 2009 00:00:00 +0100 3110866 http://www.medworm.com/index.php?rid=3047850&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01846.x Sinorhizobium meliloti associates with Medicago and Melilotus species to develop nitrogen-fixing symbioses. The agricultural relevance of these associations, the worldwide distribution of acid soils, and the remarkable acid sensitivity of the microsymbiont have all stimulated research on the responses of the symbionts to acid environments. We show here that an adaptive acid-tolerance response (ATR) can be induced in S. meliloti, as shown previously for Sinorhizobium medicae, when the bacteria are grown in batch cultures at the slightly acid pH of 6.1. In marked contrast, no increased tolerance to hydrogen ions is obtained if rhizobia are grown in a chemostat under continuous cultivation at the same pH. The adaptive ATR appears as a complex process triggered by an increased hydrogen-ion con... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3047850 Wed, 02 Dec 2009 00:00:00 +0100 3047850 http://www.medworm.com/index.php?rid=3035815&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01854.x In this study, we identified five putative carotenoid biosynthetic genes from the ascomycete Gibberella zeae (GzCarB, GzCarO, GzCarRA, GzCarT, and GzCarX). HPLC showed that the fungus produces two carotenoids: neurosporaxanthin and torulene. We deleted the five genes individually to determine their functions. GzCarB, GzCarRA, and GzCarT were required for neurosporaxanthin biosynthesis, but the deletion of GzCarX or GzCarO ([Delta]gzcarX or [Delta]gzcarO) failed to alter the production of neurosporaxanthin or torulene. [Delta]gzcarRA and [Delta]gzcarB did not produce neurosporaxanthin or torulene. [Delta]gzcarB led to the accumulation of phytoene, which is an intermediate in carotenoid biosynthesis, but [Delta]gzcarRA did not. [Delta]gzcarT produced torulene but not neurosporaxanthin. Based... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3035815 Sat, 28 Nov 2009 00:00:00 +0100 3035815 http://www.medworm.com/index.php?rid=3110867&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01870.x In this study, we compared the genomic differences between A. pleuropneumoniae strains CVCC259 (serotype 1) and CVCC261 (serotype 3) by representational difference analysis. Of the eight differential DNA sequences in the CVCC259 strain and 11 differential DNA sequences in the CVCC261 strain that we identified, seven represent known virulent genes, 10 encode putative proteins, and two encode hypothetical proteins. We also investigated the distribution of these 19 sequences among the 15 serotypes, and each serotype showed a different distribution pattern. The autotransporter adhesin occurred as a novel putative virulence factor in serotypes 1, 5, 7, 8, 9, and 11. Notably, the presence of wzm and wzt in serotypes 1, 9, and 11 and the diverse distribution of wzz and wzy in the other serotypes ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110867 Fri, 27 Nov 2009 00:00:00 +0100 3110867 http://www.medworm.com/index.php?rid=3110868&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01868.x The emerging multiple drug resistance in bacterial pathogens is complicating the treatment of diseases and hence is a major public health concern. In the present study, Vibrio cholerae O1 El Tor Ogawa isolated from a patient was examined for antibiotic susceptibility pattern, presence of SXT and its transmissibility, associated drug resistance genes and variation in the int gene and the attP attachment site of SXT. The strain showed resistance to ampicillin, polymixin B, co-trimoxazole, trimethoprim, streptomycin, spectinomycin, furazolidone, tetracycline, ciprofloxacin and nalidixic acid. The sequencing of int, the SXT-specific integrase and attP attachment site indicated that it possessed a variant of SXT with trimethoprim (dfrA1), sulphamethoxazole (sul2) and streptomycin (strB) resista... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110868 Thu, 26 Nov 2009 00:00:00 +0100 3110868 http://www.medworm.com/index.php?rid=3100207&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01867.x We report the effect of glutathione and the role of reactive oxygen species (ROS), assayed by a nitro blue tetrazolium reaction, on the antibacterial action of ciprofloxacin, gentamicin and chloramphenicol in Staphylococcus aureus 22 resistant to ciprofloxacin and gentamicin, and in S. aureus ATCC 29213 sensitive to the above three antibiotics. The association of glutathione with ciprofloxacin or gentamicin significantly reduced the value of the minimum inhibitory concentration (MIC) in resistant S. aureus 22, measured using the macrodilution method, with a concomitant increase of intracellular ROS and a decrease of extracellular ROS. However, glutathione did not induce modifications in MIC or ROS generated by chloramphenicol. Furthermore, in the sensitive S. aureus ATCC 29213, the associa... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3100207 Thu, 26 Nov 2009 00:00:00 +0100 3100207 http://www.medworm.com/index.php?rid=3029461&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01841.x Infected yellow catfish (Pelteobagrus fulvidraco) were sent from Niushan Lake Fishery, Hubei Province, China, to our laboratory for diagnosis. Macroscopic daffodil yellow mold was observed on the heads and fins of the fish and one Mucor species was isolated. Based on the morphological and molecular analysis, the species was identified as Mucor circinelloides. Its optimum growth temperature was 30 °C and it could not grow at 40 °C. The infectivity results showed wound infection could cause 100% cumulative mortalities at all experimental CFU (106, 107 and 108). The cumulative mortalities of the intraperitoneal infection increased along with the sporangiospore concentrations; the highest mortality was 90% with 108 CFU. Histopathological studies showed M. circinelloides could cause a series ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3029461 Thu, 26 Nov 2009 00:00:00 +0100 3029461 http://www.medworm.com/index.php?rid=3026354&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01850.x Two bacterial strains (DY05T and 47666-1) were isolated in Queensland, Australia, from diseased cultured crustaceans Panulirus ornatus and Penaeus monodon, respectively. On the basis of 16S rRNA gene sequence identity, the strains were shown to belong to the Harveyi clade of the genus Vibrio. Multilocus sequence analysis using five housekeeping genes (rpoA, pyrH, topA, ftsZ and mreB) showed that the strains form a monophyletic group with 94.4% concatenated sequence identity to the closest species. DNA[ndash]DNA hybridization experiments showed that strains DY05T and 47666-1 had 76% DNA similarity to each other, but (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3026354 Wed, 25 Nov 2009 00:00:00 +0100 3026354 http://www.medworm.com/index.php?rid=3022646&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01845.x The effects of overexpression of the apurinic/apyrimidinic DNA endonuclease Nfo on wet and dry heat and UV-C (254 nm) resistance of Bacillus subtilis spores with or without [alpha]/[beta]-type small, acid-soluble spore proteins (SASP) were determined. Results revealed that overexpression of Nfo [ge]50-fold in spores increased the wet heat resistance of exoA nfo B. subtilis spores (termed [alpha][minus][beta][minus]) that lack most [alpha]/[beta]-type SASP, but had no effect on these spores' UV-C resistance. Nfo overexpression also increased these spores' dry heat resistance, and to levels slightly greater than that of wild-type spores. These results are consistent: (1) with wet and dry heat (but not UV-C) generating abasic sites in [alpha][minus][beta][minus] spore DNA; (2) with dry heat g... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3022646 Tue, 24 Nov 2009 00:00:00 +0100 3022646 http://www.medworm.com/index.php?rid=3110869&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01866.x The type IV secretion system (T4SS) contributes to Brucella intracellular survival through its effector proteins. Comparative proteomic analysis showed that intracellular survival proteins are expressed differentially in a virB mutant. Interestingly, several outer membrane proteins (OMPs) are also differentially expressed, implying that T4SS might affect the OM properties of Brucella. To further evaluate the impact of T4SS on OM, in the present study, the OM proteomes were isolated and compared. Many more products of OMPs, particularly different products of the Omp25/Omp31 family, were found to be altered in the virB mutant. The transcription profiles of Omp25/Omp31 were different from those of their protein products, implying their regulation by virB at both transcriptional and post-trans... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3110869 Mon, 23 Nov 2009 00:00:00 +0100 3110869 http://www.medworm.com/index.php?rid=3075096&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01861.x The frequent coisolation of bacteria with Phytophthora and Pythium species suggests possible interspecies communication. Zoospore-free fluids (ZFF) from bacteria-free and nutrient-depleted zoospore suspensions were examined to investigate the production of autoinducer-2 (AI-2), a bacterial interspecies signal molecule, by zoosporic oomycetes. ZFF from Phytophthora nicotianae, Phytophthora sojae, and Pythium aphanidermatum triggered luminescence of the Vibrio harve7yi AI-2 reporter, indicating the presence of AI-2 in zoospore extracellular products and the potential of cross-kingdom communication between oomycetes and bacteria. The production of AI-2 by zoospores was confirmed by chemical assays. These results provide a new insight into the physiology and ecology of oomycetes. (Source: FEMS... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3075096 Mon, 23 Nov 2009 00:00:00 +0100 3075096 http://www.medworm.com/index.php?rid=3075095&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01864.x The streptococcal collagen-like protein-1, Scl1, is widely expressed by the well-recognized human pathogen group A Streptococcus (GAS). Screening of human ligands for binding to recombinant Scl1 identified cellular fibronectin and laminin as binding partners. Both ligands interacted with the globular domain of Scl1, which is also able to bind the low-density lipoprotein. Native Scl1 mediated GAS adherence to ligand-coated glass cover slips and promoted GAS internalization into HEp-2 cells. This work identifies new ligands of the Scl1 protein that are known to be important in GAS pathogenesis and suggests a novel ligand-switching mechanism between blood and tissue environments, thereby facilitating host colonization and GAS dissemination. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3075095 Mon, 23 Nov 2009 00:00:00 +0100 3075095 http://www.medworm.com/index.php?rid=3011973&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01844.x Protein secretion plays a very important role in the virulence of the bacterium Dickeya dadantii, the causative agent of soft rot disease, in a wide range of plant species. We studied the contribution of the twin-arginine translocation (Tat) protein system to the adaptation of D. dadantii 3937 to different growth conditions and to the interaction with the plant host. First, a list of 44 putative Tat substrates was obtained using bioinformatic programs taking advantage of the availability of the complete sequence of this bacterium. Second, a tatC mutant strain was constructed and analysed. The mutant displayed a pleiotropic phenotype, showing limited growth in an iron-depleted medium, higher sensitivity to copper, reduced motility on soft agar plates and attenuated virulence in witloof chic... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3011973 Fri, 20 Nov 2009 00:00:00 +0100 3011973 http://www.medworm.com/index.php?rid=3070780&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01859.x Vanillin dehydrogenases (VDHs) were purified and characterized from two bacterial strains that have different pH dependencies for growth. The alkaliphile Micrococcus sp. TA1, isolated from an alkaline spa, can grow on several aromatic compounds such as ferulic acid, vanillin, vanillic acid, and protocatechuic acid under alkaline conditions. The neutrophile Burkholderia cepacia TM1, which was isolated previously, also grew on the above-mentioned compounds because they functioned as the sole carbon source under neutral conditions. Purified VDHs showed activities toward some aromatic aldehydes. These enzymes have the same subunit molecular mass of about 57 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but differed in some of their observed properties. Native ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3070780 Wed, 18 Nov 2009 00:00:00 +0100 3070780 http://www.medworm.com/index.php?rid=3003421&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01836.x In this study, we determined that PhaR binds to an 11-bp palindromic sequence, 5'-CTGCN3GCAG-3', located at nucleotides [minus]69 to [minus]59 and [minus]97 to [minus]87 relative to the translation start site of phaP. Substitution of the three spacer nucleotides with any three or four nucleotides in this sequence had no effect on PhaR binding, but all other base deletions or substitutions in this sequence abolished its ability to bind PhaR both in vitro and in vivo. These results suggest that PhaR regulates the expression of phaP in R. sphaeroides FJ1. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3003421 Wed, 18 Nov 2009 00:00:00 +0100 3003421 http://www.medworm.com/index.php?rid=3066643&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01857.x Persisters are a small population of slowly growing or nongrowing bacteria that are phenotypically resistant to antibiotics, but the mechanisms involved are not well understood. The aim of this study is to determine new mechanisms underlying antibiotic-tolerant persisters. The Escherichia coli deletion mutant library was screened to identify mutants that had a defect in persister survival after exposure to ampicillin for 24 h or 5 days. The identified mutants and the parent strain were subjected to minimum inhibitory concentration (MIC) and minimum bactericidal tests and antibiotic or stress conditions in exposure assays. sucB and ubiF mutants deficient in energy production were identified from the mutant screens to have defective persister survival as demonstrated by higher susceptibility... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3066643 Tue, 17 Nov 2009 00:00:00 +0100 3066643 http://www.medworm.com/index.php?rid=3092402&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01855.x Deinococcus radiodurans tolerates extensive DNA damage and exhibits differential expression of various genes associated with the growth of the organism and DNA repair. In cells treated with [gamma] radiation, the levels of cyclic AMP (cAMP) and ATP increased rapidly by differentially regulating adenylyl cyclase (AC) and 2'3' cAMP phosphodiesterase. The levels of cAMP, ATP, AC and protein kinases were high when phosphodiesterase activity was low. These cells exhibited in vivo inhibition of nucleolytic function by reversible protein phosphorylation and contained the comparatively higher levels of total phosphoproteins. We suggest that Deinococcus, a prokaryote, uses DNA damage-induced signaling mechanism as evidenced by [gamma] radiation-induced synthesis of secondary messengers and signalin... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3092402 Mon, 16 Nov 2009 00:00:00 +0100 3092402 http://www.medworm.com/index.php?rid=3035816&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01853.x To study the mechanism of action of the lactobacilli, splenocytes were incubated with lactobacilli. We compared the ability of live and lyophilized Lactobacillus casei, Lactobacillus rhamnosus GG and Lactobacillus delbrueckii ssp. bulgaricus to modulate the production of interleukin 12p40 (IL-12p40), tumor necrosis factor [alpha] and IL-10 by splenocytes from C57BL/6 and BALB/c mice. Blocking contact between lactobacilli and immune cells abrogated all cytokine production. Toll-like receptor 2 (TLR2) was partially responsible, but not TLR4 or TLR9, for the induction of cytokine production in splenocytes. All cytokine production declined to basal levels when bacterial phagocytosis was inhibited. This shows that lactobacilli stimulation of cytokine production in splenocytes requires the proce... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3035816 Fri, 13 Nov 2009 00:00:00 +0100 3035816 http://www.medworm.com/index.php?rid=2988641&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01825.x Cyclic bis(3'[ndash]5')diguanylic acid (cyclic-di-GMP) functions as a second messenger in diverse species of bacteria to trigger wide-ranging physiological changes. We measured cyclic-di-GMP and its structural analogs such as cyclic bis(3'[ndash]5')guanylic/adenylic acid (cyclic-GpAp), cyclic bis(3'[ndash]5')guanylic/inosinic acid (cyclic-GpIp) and monophosphorothioic acid of cyclic-di-GMP (cyclic-GpGps) for effects on the biofilm formation of Staphylococcus aureus and Pseudomonas aeruginosa. We constructed a knockout mutant of SA0701, which is a GGDEF motif protein relevant to diguanylate cyclase from S. aureus 2507. We confirmed that the biofilm formation of this mutant (MS2507[Delta]SA0701) was reduced. Cyclic-di-GMP corresponding to physiological intracellular levels given in the cultu... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2988641 Fri, 13 Nov 2009 00:00:00 +0100 2988641 http://www.medworm.com/index.php?rid=3092403&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01849.x An enzyme with mannosyl glycoprotein endo-N-acetyl-[beta]-d-glucosaminidase (ENGase)-type activity was partially purified from the extracellular medium of the mould Hypocrea jecorina (Trichoderma reesei). Internal peptides were generated and used to identify the gene in the T. reesei genome. The active enzyme is processed both at the N- and at the C-terminus. High-mannose-type glycoproteins are good substrates, whereas complex-type glycans are not hydrolysed. The enzyme represents the first fungal member of glycoside hydrolase family 18 with ENGase-type activity. Bacterial ENGases and the fungal chitinases belonging to the same family show very low homology with Endo T. Database searches identify several highly homologous genes in fungi and the activity is also found within other Trichoder... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3092403 Wed, 11 Nov 2009 00:00:00 +0100 3092403 http://www.medworm.com/index.php?rid=2980810&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01839.x We explored the potential of the cox1 gene in the species resolution of soil fungi and compared it with the nuclear internal transcribed spacer (ITS) and small subunit (SSU)-rDNA. Conserved primers allowing the amplification of the fungal cox1 gene were designed, and a total of 47 isolates of Zygomycota and Ascomycota were investigated. The analysis revealed a lack of introns in >90% of the isolates. Comparison of the species of each of the six studied genera showed high interspecific sequence polymorphisms. Indeed, the average of nucleotide variations (4.2[ndash]11%) according to the genus, due mainly to the nucleotide substitutions, led to the taxonomic resolution of all the species studied regarding both ITS and SSU-rDNA, in which (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2980810 Wed, 11 Nov 2009 00:00:00 +0100 2980810 http://www.medworm.com/index.php?rid=2976981&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01833.x Intracellular copper routing in Enterococcus hirae is accomplished by the CopZ copper chaperone. Under copper stress, CopZ donates Cu+ to the CopY repressor, thereby releasing its bound zinc and abolishing repressor[ndash]DNA interaction. This in turn induces the expression of the cop operon, which encodes CopY and CopZ, in addition to two copper ATPases, CopA and CopB. To gain further insight into the function of CopZ, the yeast two-hybrid system was used to screen for proteins interacting with the copper chaperone. This led to the identification of Gls24, a member of a family of stress response proteins. Gls24 is part of an operon containing eight genes. The operon was induced by a range of stress conditions, but most notably by copper. Gls24 was overexpressed and purified, and was shown... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2976981 Tue, 10 Nov 2009 00:00:00 +0100 2976981 http://www.medworm.com/index.php?rid=2970079&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01831.x In this study, we compared PNPase activity in three virulent and four benign strains of D. nodosus and found that PNPase activity is lower in virulent strains. We disrupted the pnpA gene in three benign D. nodosus strains and two virulent strains and showed that deletion of the S1 domain of PNPase reduced catalytic activity. In all but one case, deletion of the PNPase S1 domain had no effect on the thermostability of extracellular proteases. However, this deletion resulted in an increase in twitching motility in benign, but not in virulent strains. Reconstruction of the pnpA gene in two mutant benign strains reduced twitching motility to the parental level. These results support the hypothesis that PNPase is a virulence repressor in benign strains of D. nodosus. (Source: FEMS Microbiology ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970079 Sat, 07 Nov 2009 00:00:00 +0100 2970079 http://www.medworm.com/index.php?rid=3035817&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01847.x Salmonella enterica serovar Typhimurium is an animal and zoonotic pathogen of worldwide importance. Intestinal colonization, induction of enteritis and systemic translocation by this bacterium requires type III protein secretion. Strategies that target this process have the potential to control infection, pathology and transmission. We defined the global transcriptional response of S. Typhimurium to INP0403, a member of a family of salicylidene acylhydrazides that inhibit type III secretion (T3S). INP0403 treatment was associated with reduced transcription of genes involved in T3S, but also increased transcription of genes associated with iron acquisition. We show that INP0403 restricts iron availability to Salmonella, and that inhibition of T3S system-1 by INP0403 is, at least in part, re... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3035817 Fri, 06 Nov 2009 00:00:00 +0100 3035817 http://www.medworm.com/index.php?rid=3026355&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01848.x In conclusion, we found that Sov is an outer membrane protein participating in the secretion of gingipains and that the C-terminal region of Sov is exposed to the extracellular milieu and involved in the modulation of Sov function. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3026355 Fri, 06 Nov 2009 00:00:00 +0100 3026355 http://www.medworm.com/index.php?rid=2966792&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01823.x Staphylococcus aureus, Staphylococcus hyicus, and Staphylococcus chromogenes are known to cause skin infections in human or animals by producing exfoliative toxins (ETs). Staphylococcus pseudintermedius can also cause canine pyoderma, but no exfoliative toxins or similar toxins have been reported. PCR with degenerate primers targeted to the conserved regions in ETA, ETB, and ETD from S. aureus and SHETB from S. hyicus, and subsequent chromosome walking identified a novel gene, designated as exi (exfoliative toxin of pseudintermedius) in S. pseudintermedius. EXI had significant homologies with the exfoliative toxins (43[ndash]68% identity), particularly with ETB (67.1%), ETD (67.9%), and SHETB (65.1%). Phylogenetic analysis showed close relation between EXI and ETB with a bootstrap value of... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2966792 Fri, 06 Nov 2009 00:00:00 +0100 2966792 http://www.medworm.com/index.php?rid=2962846&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01815.x Important features of the enteroinvasive Escherichia coli (EIEC) phenotype and gene expression likely to confer EIEC with a lower ability to cause disease than Shigella flexneri were described here for the first time. To confirm the lower pathogenicity of EIEC, we have analyzed the keratoconjunctivitis developed in guinea-pigs with EIEC or S. flexneri. Shigella flexneri induced a more pronounced proinflammatory response, whereas EIEC induced a mild form of the disease. EIEC showed a significantly less efficient cell-to-cell Caco-2 dissemination when compared with S. flexneri. Plaques formed by EIEC during intercellular spreading were four times smaller than those formed by S. flexneri. At the molecular level, the lower expression of virulence genes by EIEC during infection of Caco-2 cells ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2962846 Thu, 05 Nov 2009 00:00:00 +0100 2962846 http://www.medworm.com/index.php?rid=3035819&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01843.x Periplasmic cyclic [beta]-1,2-glucans play a crucial role in symbiosis as well as in hypo-osmotic adaptation for rhizobia. These glucans are modified in many species by anionic substituents such as glycerophosphoryl and succinyl ones, but their role remains to be examined. In this work, the cgmA homolog is shown to be responsible for glycerophosphorylation of cyclic [beta]-1,2-glucans in Mesorhizobium loti. The mutation in cgmA converted most anionic glucans into neutral ones, leaving a small amount of succinylated ones. An additional mutation in opgC, which encodes a succinyltransferase homolog, abolished the residual succinyl substituents in the cgmA-mutant background. The double mutant in cgmA and opgC did not show any significant phenotypic differences from the wild type during both ve... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3035819 Tue, 03 Nov 2009 00:00:00 +0100 3035819 http://www.medworm.com/index.php?rid=2954197&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01822.x A real-time nucleic acid sequence-based amplification assay, targeting tmRNA, was designed for the rapid identification of Staphylococcus aureus. The selectivity of the assay was confirmed against a panel of 76 Staphylococcus strains and species and 22 other bacterial species. A detection limit of 1 cell equivalent was determined for the assay. A chimeric in vitro transcribed internal amplification control was developed and included in the assay. Application of the assay in natural and artificially contaminated unpasteurized (raw) milk enabled detection of 1[ndash]10 CFUS. aureus mL[minus]1 in 3[ndash]4 h, without the need for culture enrichment. Staphylococcus aureus was detected in all artificially contaminated milk samples (n=20) and none of the natural milk samples (n=20). Microbiologi... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2954197 Tue, 03 Nov 2009 00:00:00 +0100 2954197 http://www.medworm.com/index.php?rid=2950408&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01793.x Xanthomonas oryzae pathovar oryzae (Xoo) causes bacterial blight disease in rice (Oryza sativa L.). For a study of function, we constructed a random insertion mutant library of Xoo using a Tn5 transposon and isolated the mutant strain (M11; aroK∷Tn5) that had extremely low pigment production. In addition, M11 had decreased virulence against the susceptible rice cultivar IR24. Thermal asymmetric interlaced-PCR and sequence analysis of M11 revealed that the transposon was inserted into the aroK gene (which encodes a shikimate kinase). To investigate the expression patterns of the pigment- and virulence-deficient mutant, DNA microarray analysis was performed. In addition, reverse transcriptase-PCR was performed to confirm the expression levels of several genes, including the aro genes ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2950408 Mon, 02 Nov 2009 00:00:00 +0100 2950408 http://www.medworm.com/index.php?rid=3029462&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01840.x Biofilms are bacterial communities enclosed within an extracellular matrix of polysaccharides produced by the bacteria, which adhere to a living or an inert macrosurface. In nature, biofilms constitute a protected growth modality allowing bacteria to survive in hostile environments. Studies of environmental isolates have revealed a highly ordered, three-dimensional organization of the extracellular matrix, which has important implications for biofilm physiology. The zone of soil immediately surrounding a plant root where complex biological and ecological processes occur, termed rhizosphere, forms an environment that fulfills the requirements for biofilm formation, including sufficient moisture and supply of nutrients, which are provided by the plant. Biofilm formation on plants appears to ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3029462 Fri, 30 Oct 2009 00:00:00 +0100 3029462 http://www.medworm.com/index.php?rid=2943308&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01812.x A quick and sensitive DNA-based assay for identifying the black truffle species Tuber melanosporum is presented. Both direct PCR and species-specific primers are used to amplify a phylogenetically informative region of T. melanosporum rDNA. This method was successfully used to screen fresh and frozen T. melanosporum fruitbodies, and could be modified for the molecular detection of other truffle and mushroom species. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943308 Fri, 30 Oct 2009 00:00:00 +0100 2943308 http://www.medworm.com/index.php?rid=2943309&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01834.x (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943309 Thu, 29 Oct 2009 00:00:00 +0100 2943309 http://www.medworm.com/index.php?rid=3011974&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01835.x Vibrio cholerae colonizes the human intestine and causes the acute diarrheal disease cholera. Flagellar-mediated chemotaxis contributes to intestinal colonization as well as infectivity. The virulence-regulatory protein ToxT activates transcription of the genes encoding the major virulence factors cholera toxin and toxin coregulated pilus. ToxT additionally activates transcription of two genes, tcpI and acfB, located within the Vibrio Pathogenicity Island predicted to encode methyl-accepting chemoreceptors. We show that disruption of either tcpI or acfB individually does not noticeably affect V. cholerae intestinal colonization within the infant mouse, but disruption of both tcpI and acfB leads to a decrease in intestinal colonization. These results suggest that TcpI and AcfB may have over... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3011974 Wed, 28 Oct 2009 00:00:00 +0100 3011974 http://www.medworm.com/index.php?rid=2980812&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01837.x The PhoBR regulatory system is required for the induction of multiple genes under conditions of phosphate limitation. Here, we examine the role of PhoB in biofilm formation and environmental stress response in Vibrio cholerae of the El Tor biotype. Deletion of phoB or hapR enhanced biofilm formation in a phosphate-limited medium. Planktonic and redispersed biofilm cells of the [Delta]phoB mutant did not differ from wild type for the expression of HapR, suggesting that PhoB negatively affects biofilm formation through an HapR-independent pathway. The [Delta]phoB mutant exhibited elevated expression of exopolysaccharide genes vpsA and vpsL compared with the wild type. Deletion of hapR enhanced the expression of the positive regulator vpsT, but had no effect on the expression of vpsR. In cont... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2980812 Wed, 28 Oct 2009 00:00:00 +0100 2980812 http://www.medworm.com/index.php?rid=2980811&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01838.x Magnetotactic bacteria (MTB), which can mineralize nanosized magnetite or greigite crystals within cells, play important roles in biogeochemical processes, for example iron and sulfur cycling, and depositional remanent magnetization acquisitions. Despite decades of research, the knowledge of MTB distribution and ecology is still limited. In the present study, we investigated the temporal variation of MTB communities in freshwater sediment microcosms based on 16S rRNA genes and unifrac analyses. Two microcosms (MY8 and MY11) collected from two separate sites in Lake Miyun (Beijing, China) were analyzed. The majority of retrieved sequences belonged to alphaproteobacterial magnetotactic cocci in both microcosms (representing 64.29% of clones from MY8 and 100% of clones from MY11), whereas so-... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2980811 Wed, 28 Oct 2009 00:00:00 +0100 2980811 http://www.medworm.com/index.php?rid=2930652&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01814.x Gram-positive bacteria, including Listeria monocytogenes, adjust membrane fluidity by shortening the fatty acid chain length and increasing the proportional production of anteiso fatty acids at lower growth temperatures. The first condensation reaction in fatty acid biosynthesis is carried out by [beta]-ketoacyl-acyl carrier protein synthase III (FabH), which determines the type of fatty acid produced in bacteria. Here, we measured the initial rates of FabH-catalyzed condensation of malonyl-acyl carrier protein and alternate branched-chain precursor acyl-CoAs utilizing affinity-purified His-tagged L. monocytogenes FabH heterologously expressed in Escherichia coli. Listeria monocytogenes FabH showed a preference for 2-methylbutyryl-CoA, the precursor of odd-numbered anteiso fatty acids, at ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2930652 Tue, 27 Oct 2009 00:00:00 +0100 2930652 http://www.medworm.com/index.php?rid=2976982&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01832.x In both rod-shaped Bacillus subtilis and Escherichia coli cells, Min proteins are involved in the regulation of division septa formation. In E. coli, dynamic oscillation of MinCD inhibitory complex and MinE, a topological specificity protein, prevents improper polar septation. However, in B. subtilis no MinE is present and no oscillation of Min proteins can be observed. The function of MinE is substituted by that of an unrelated DivIVA protein, which targets MinCD to division sites and retains them at the cell poles. We inspected cell division when the E. coli Min system was introduced into B. subtilis cells. Expression of these heterologous Min proteins resulted in cell elongation. We demonstrate here that E. coli MinD can partially substitute for the function of its B. subtilis protein c... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2976982 Fri, 23 Oct 2009 00:00:00 +0100 2976982 http://www.medworm.com/index.php?rid=3035818&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01827.x Yersinia pestis PsaA is an adhesin important for the establishment of bacterial infection. PsaA synthesis requires the products of the psaEFABC genes. Here, by prediction analysis, we identified a PsaA signal sequence with two signal peptidase (SPase) cleavage sites, type-I and type-II (SPase-I and SPase-II). By Edman degradation and site-directed mutagenesis, the precise site for one of these Spase-I PsaA cleavage sites was located between alanine and serine at positions 31 and 32, respectively. Yersinia pestis psaA expression and the role of the PsaB and PsaC proteins were evaluated in recombinant attenuated Salmonella Typhimurium vaccine strains. PsaA was detected in total extracts as a major 15-kDa (mature) and 18-kDa (unprocessed) protein bands. PsaA synthesis was not altered by a [De... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3035818 Thu, 22 Oct 2009 00:00:00 +0100 3035818 http://www.medworm.com/index.php?rid=3011975&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01826.x Bacterial surface polysaccharides are crucial for establishment of successful rhizobia[ndash]legume symbiosis, and in most bacteria, are also critical for biofilm formation and surface colonization. In Sinorhizobium meliloti, the regulatory protein MucR controls exopolysaccharide production. To clarify the relationship between exopolysaccharide synthesis and biofilm formation, we studied mucR expression under growth conditions that influence attachment to polyvinylchloride, developed a microtiter plate assay to quantify biofilm formation in S. meliloti strain Rm1021 and mutants defective in succinoglycan (EPS I) and/or galactoglucan (EPS II) production, and analyzed expression of EPS I and EPS II genes by quantitative reverse transcriptase-PCR. Consistent with previous studies of planktoni... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3011975 Thu, 22 Oct 2009 00:00:00 +0100 3011975 http://www.medworm.com/index.php?rid=2970082&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01828.x Lancefield group C Streptococcus dysgalactiae is an emerging fish pathogen, which was first isolated in 2002 in Japan. Streptococcus dysgalactiae isolates collected from diseased fish in Japan (n=12), Taiwan (n=12), China (n=2), Malaysia (n=3), and Indonesia (n=1) were characterized using biased sinusoidal field gel electrophoresis (BSFGE), sodA gene sequence analysis, and antimicrobial susceptibility. These isolates exhibited high phenotypic homogeneity irrespective of the countries from where the strains were collected. Seventeen isolates were found to be resistant to oxytetracycline and carried the tet(M) gene, except for the strains collected in Taiwan and the PP1564 strain collected in China. The sodA gene sequence analysis revealed that 23 isolates were identical, except for one Japa... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970082 Thu, 22 Oct 2009 00:00:00 +0100 2970082 http://www.medworm.com/index.php?rid=2970081&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01829.x In this study, a fast and efficient strategy has been developed for identifying and isolating novel cry genes from Bacillus thuringiensis by combining the PCR-restriction fragment length polymorphism and the single-oligonucleotide nested-PCR method. Using this method, one novel holotype cry gene, cry30Fa1, encoding a polypeptide of 687 amino acid residues with a molecular mass of 77.1 kDa, 74% identical to Cry30Aa1, was cloned from the B. thuringiensis strain BtMC28. Furthermore, the cry30Fa1 gene was successfully expressed in Escherichia coli BL21 (DE3). The Cry30Fa1 proteins, isolated from the cultures of recombinant E. coli, had remarkable insecticidal effects against Plutella xylostella and Aedes aegypti with LC50 at 6.477 and 15.359 [mu]g mL[minus]1, respectively. Our results strongly... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970081 Thu, 22 Oct 2009 00:00:00 +0100 2970081 http://www.medworm.com/index.php?rid=2970080&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01830.x The qpo gene of Aggregatibacter actinomycetemcomitans encodes a triheme c-containing membrane-bound enzyme, quinol peroxidase (QPO) that catalyzes peroxidation reaction in the respiratory chain and uses quinol as the physiological electron donor. The QPO of A. actinomycetemcomitans is the only characterized QPO, but homologues of the qpo gene are widely distributed among many gram-negative bacteria, including Haemophils ducreii, Bacteroides fragilis, and Escherichia coli. One-third of the amino acid sequence of QPO from the N-terminal end is unique, whereas two-thirds of the sequence from the C-terminal end exhibits high homology with the sequence of the diheme bacterial cytochrome c peroxidase. In order to obtain sufficient protein for biophysical studies, the present study aimed to overp... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970080 Thu, 22 Oct 2009 00:00:00 +0100 2970080 http://www.medworm.com/index.php?rid=2915807&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01800.x C-1027 is a chromoprotein of the nine-membered enediyne antitumour antibiotic family, comprising apoprotein to stabilize and transport the enediyne chromophore. The disruption of apoprotein gene cagA within the C-1027 biosynthetic gene cluster abolished C-1027 holo-antibiotic production detected by an antibacterial assay, as well as the expression of the apoprotein and C-1027 chromophore extracted following protein precipitation of the culture supernatant. Complementation of the cagA-disrupted mutant AKO with the intact cagA gene restored C-1027 production, suggesting that cagA is indispensable for holo-antibiotic production. Overexpression of cagA in the wild-type strain resulted in a significant increase in C-1027 production as expected. Surprisingly, electrospray ionization (ESI)-MS and... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2915807 Wed, 21 Oct 2009 23:00:00 +0100 2915807 http://www.medworm.com/index.php?rid=2950409&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01824.x The CcoP subunit of cytochrome oxidase cbb3 of Neisseria gonorrhoeae is predicted to include a C-terminal extension in which there is a C-A-A-C-H- motif typical of heme attachment sites in c-type cytochromes. Substitutions of key cysteine and histidine residues of this motif resulted in mutants that grew normally in oxygen-sufficient cultures and reduced oxygen at the same rate as the parent strain. In contrast, after oxygen-limited growth in the presence of nitrite, rates of nitrite reduction were significantly lower than those of the parent, consistent with a role for this third heme-binding domain in electron transfer to the nitrite reductase, AniA, located in the outer membrane. As the mutants were still able to reduce nitrite at approximately 65% of the rate of the parent, there are m... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2950409 Wed, 21 Oct 2009 00:00:00 +0100 2950409 http://www.medworm.com/index.php?rid=2901508&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01809.x This study was designed to develop a multiplex PCR method with five specific primer pairs for the detection of Salmonella spp., Salmonella subspecies I, Salmonella enterica serovars Typhimurium, Typhi and Enteritidis. A multiplex PCR was constructed with five primer pairs for the detection of Salmonella and pathogenic Salmonella serovars, including a specific primer pair for Salmonella Typhi, based on the sequence comparison between genomic DNA sequences of 12 Salmonella strains. Each primer pair was specifically targeted to Salmonella spp., Salmonella subspecies I, Salmonella Typhimurium, Typhi and Enteritidis. This multiplex PCR was evaluated with various DNAs of Salmonella serovars that yielded high specificity for amplifying the expected PCR products of Salmonella serovars. Using this ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2901508 Fri, 16 Oct 2009 23:00:00 +0100 2901508 http://www.medworm.com/index.php?rid=2898391&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01804.x Triclosan is a biocide whose wide use has raised a debate about the potential benefits vs. hazards of the incorporation of antimicrobials in consumer products. The purpose of the present study was to determine whether exposure of biofilms of Salmonella enterica serovar Typhimurium to triclosan influences the tolerance of the bacteria towards antibiotics such as ciprofloxacin and vice versa. A synergistic antibiofilm activity was observed when the biofilms were treated with triclosan before or together with ciprofloxacin, and an additive activity was observed with planktonic cells. For example 500 [mu]g mL[minus]1 triclosan and 500 [mu]g mL[minus]1 ciprofloxacin reduced the number of viable cells in the biofilm by 1.6 and 0.5 log, respectively. However, the sequential treatment of 500 [mu]g... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2898391 Thu, 15 Oct 2009 23:00:00 +0100 2898391 http://www.medworm.com/index.php?rid=3047851&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01821.x The use of Cry proteins from Bacillus thuringiensis are an important strategy for biological control. Recently it has been demonstrated that Cry hybrid proteins (by domain swapping) resulted in improved toxicities in comparison with parental proteins. Here, an SN1917 hybrid toxin was constructed and tested against Colombian pest insects Tecia solanivora (Lepidoptera: Gelechiidae), a severe potato pest, and Hypothenemus hampei (Coleoptera: Scolytidae), which attacks coffee crops. The SN1917 protoxin had a concentration causing 50% mortality (LC50) of 392 ng cm[ndash]2, and SN1917 toxin showed an LC50 of 201 ng cm[ndash]2 against T. solanivora first instar larvae. The two parental toxins (Cry1B and Cry1I) used to make this new hybrid protein caused a mortality of 60% and 52%, respectively. U... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3047851 Thu, 15 Oct 2009 00:00:00 +0100 3047851 http://www.medworm.com/index.php?rid=2894043&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01803.x The opportunistic pathogen Pseudomonas aeruginosa PA14 possesses four fimbrial cup clusters, which may confer the ability to adapt to different environments. cupD lies in the pathogenicity island PAPI-1 next to genes coding for a putative phosphorelay system composed of the hybrid histidine kinase RcsC and the response regulator RcsB. The main focus of this work was the regulation of cupD at the mRNA level. It was found that the HN-S-like protein MvaT does not exert a strong influence on cupD transcript levels, as it does for cupA. cupD transcription is higher in cultures grown at 28 °C, which agrees with a cupD mutant presenting attenuated virulence only in a plant model, but not in a mouse model of infection. Whereas an rcsC in-frame deletion mutant presented higher levels of cupD mRNA,... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2894043 Wed, 14 Oct 2009 23:00:00 +0100 2894043 http://www.medworm.com/index.php?rid=2943310&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01820.x Bacteremia is a common systemic disease caused by Acinetobacter baumannii, an important hospital-acquired pathogen among critically ill patients. The complement system is central to innate immune defense against invading bacteria in the blood. The present study investigated the susceptibility of clinical A. baumannii isolates to normal human sera (NHS), and determined the resistance mechanism of A. baumannii against complement-mediated lysis. The survival of A. baumannii isolates from bacteremic patients was significantly decreased in undiluted NHS, but they were resistant to 40% NHS. The alternative complement pathway was responsible for the direct killing of bacteria. The main regulator of the alternative complement pathway, factor H, bound to the surface of live A. baumannii treated wit... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943310 Tue, 13 Oct 2009 00:00:00 +0100 2943310 http://www.medworm.com/index.php?rid=2886195&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01798.x Staphylococcus saprophyticus, an important cause of urinary tract infections in young women, expresses the surface protein SdrI, a member of the serine-aspartate repeat (SD) protein family. Here we analyse the fibronectin-binding ability of SdrI, as S. saprophyticus is known to bind fibronectin and there is no known SD protein with this function. This protein does not contain the binding motif typical for fibronectin-binding proteins. Using recombinant fragments of SdrI, we localized the binding domain in the A region and show that SdrI bound to the N-terminal 30-kDa fragment of fibronectin. The fibronectin-binding function was shown in the natural host using an SdrI knockout mutant that showed decreased binding to fibronectin compared with wild-type strain 7108. (Source: FEMS Microbiology... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2886195 Mon, 12 Oct 2009 23:00:00 +0100 2886195 http://www.medworm.com/index.php?rid=2970083&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01819.x Isothermal calorimetry measures the heat flow of biological processes, which is proportional to the rate at which a given chemical or physical process takes place. Modern isothermal microcalorimeters make measurements of less than a microwatt of heat flow possible. As a result, as few as 10 000[ndash]100 000 active bacterial cells in culture are sufficient to produce a real-time signal dynamically related to the number of cells present and their activity. Specimens containing bacteria need little preparation, and isothermal microcalorimetry (IMC) is a nondestructive method. After IMC measurements, the undisturbed samples can be evaluated by any other means desired. In this review, we present a basic description of microcalorimetry and examples of microbiological applications of IMC for med... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970083 Mon, 12 Oct 2009 00:00:00 +0100 2970083 http://www.medworm.com/index.php?rid=2958545&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01818.x In this study, we characterize the putative cPLA2-like protein, AoPlaA, in the filamentous fungus Aspergillus oryzae. When AoPlaA-EGFP was expressed in A. oryzae, it localized to the tubular structures that was costained by the marker dye for the mitochondria. A biochemical fractionation experiment showed that AoPlaA was present in the mitochondria-enriched fraction. The presence of an N-terminal cleavable mitochondrial targeting signal in AoPlaA was demonstrated by N-terminal amino acid sequence analysis, and by showing that chimeric proteins consisting of N-terminal 65 or 50 amino acids of AoPlaA fused to enhanced green fluorescent protein (EGFP) localized to the mitochondria. Submitochondrial fractionation of AoPlaA expressed in Saccharomyces cerevisiae demonstrated that AoPlaA localize... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2958545 Sat, 10 Oct 2009 00:00:00 +0100 2958545 http://www.medworm.com/index.php?rid=2943312&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01816.x Methanotrophs oxidize methane to methanol using the enzyme methane monooxygenase. Methylosinus trichosporium OB3b has two such enzymes: a membrane-bound particulate methane monooxygenase (pMMO) and a soluble, cytoplasmic methane monooxygenase (sMMO). In methanotrophs possessing both enzymes, the expression of the genes encoding sMMO and pMMO is regulated by copper ions, with sMMO expressed solely when copper is limiting. Virtually nothing is known about the specific machinery involved in the copper-regulated transcription of mmo genes except the identification of two proteins necessary for the expression: a [sigma]54-dependent transcriptional activator, MmoR, and a putative GroEL-like chaperone, MmoG. Genes encoding mmoR and mmoG are located immediately upstream of those encoding sMMO in t... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943312 Sat, 10 Oct 2009 00:00:00 +0100 2943312 http://www.medworm.com/index.php?rid=2943311&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01817.x In Pseudomonas aeruginosa, acyl-homoserine-lactone quorum sensing (acyl-HSL QS) regulates the expression of virulence factors and biofilm formation in response to cell density. The RsaL protein represses transcription of the lasI gene, encoding the 3OC12-HSL signal synthase. The level of 3OC12-HSL is 10-fold higher in an rsaL mutant than in the wild type. In this work, we studied the effect of 3OC12-HSL overproduction caused by the rsaL mutation by comparing the transcriptional profiles and virulence-related phenotypes of a P. aeruginosa rsaL mutant and its wild-type parent. Results showed that the rsaL mutant overproduces secreted virulence factors (pyocyanin, elastase, hemolysins), displays increased twitching and swarming motility and is hypervirulent compared with the wild type. Intere... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943311 Sat, 10 Oct 2009 00:00:00 +0100 2943311 http://www.medworm.com/index.php?rid=2875415&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01802.x The C-1027 enediyne antitumor antibiotic from Streptomyces globisporus possesses an (S)-3-chloro-5-hydroxy-[beta]-tyrosine moiety, the chloro- and hydroxy-substituents of which are installed by a flavin-dependent halogenase SgcC3 and monooxygenase SgcC, respectively. Interestingly, a single flavin reductase, SgcE6, can provide reduced flavin to both enzymes. Bioinformatics analysis reveals that, similar to other flavin reductases involved in natural product biosynthesis, SgcE6 belongs to the HpaC-like subfamily of the Class I flavin reductases. The present study describes the steady-state kinetic characterization of SgcE6 as a strictly NADH- and FAD-specific enzyme. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2875415 Thu, 08 Oct 2009 23:00:00 +0100 2875415 http://www.medworm.com/index.php?rid=2871370&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01791.x Francisella tularensis is a highly virulent bacterial species that causes various forms of tularemia in humans. The urgency in understanding the pathogenesis of these diseases has stimulated unprecedented interest in this bacterial species over the past few years. Recent findings underscore a number of important distinctions between the Francisella ssp. and emphasize the importance of using type A F. tularensis strains when characterizing pathophysiological responses that are relevant to the lethal forms of human disease. This review focuses on the mediators of cell death induction in infected tissues and the implications of these processes on the pathophysiological changes observed in various host species. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2871370 Wed, 07 Oct 2009 23:00:00 +0100 2871370 http://www.medworm.com/index.php?rid=2970084&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01813.x Legionella pneumophila is an intracellular pathogen causing pneumonia-like disease in humans. A 43-kb putative heavy metal efflux gene island was found on the L. pneumophila genome. Large Legionella deletion strains of the metal efflux genes were tested in human THP-1-derived macrophages and amoebal Acanthamoeba castellanii cells and were able to survive and replicate similar to the wild type, suggesting that they do not play a significant role within the intracellular environment. Examination of the sequence of this genomic island revealed that some genes were not accurately annotated and there were no known metal-responsive regulators encoded in this region. Therefore, functional roles of these metal resistance genes were tested by conducting metal resistance assays. Individual genes wer... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2970084 Wed, 07 Oct 2009 00:00:00 +0100 2970084 http://www.medworm.com/index.php?rid=3011976&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01811.x Cell-surface expression of phytase allows the enzyme to be expressed and anchored on the cell surface of Pichia pastoris. This avoids tedious downstream processes such as purification and separation involved with extracellular expression. In addition, yeast cells with anchored proteins can be used as a whole-cell biocatalyst with high value added. In this work, the phytase was expressed on the cell surface of P. pastoris with a glycosylphosphatidylinositol anchoring system. The recombinant phytase was shown to be located at the cell surface. The cell-surface phytase exhibited high activity with an optimal temperature at 50[ndash]55 °C and two optimal pH peaks of 3 and 5.5. The surface-displayed phytase also exhibited similar pH stability and pepsin resistance to the native and secreted ph... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=3011976 Mon, 05 Oct 2009 00:00:00 +0100 3011976 http://www.medworm.com/index.php?rid=2943313&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01810.x During the course of investigation on pythiaceous fungi occurring in the Burgundian vineyards, a new species of Pythium has been isolated. This oomycete is characterized by its nonproliferating and nonsporulating, spherical to cylindrical type of sporangia (hyphal bodies) germinating through germ tubes, smooth-walled oogonia that are supplied with hypogynous, monoclinous or rarely diclinous antheridia, and smooth-walled oospores. The antheridial cells are very prominent and are reminiscent of Pythium bifurcatum, Pythium segnitium and Pythium longandrum described previously by the author. The internal transcribed spacer region of the rRNA of this new species is composed of 883 bases, which is quite different from that of the closest relatives. Morphological and molecular features of this ne... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2943313 Mon, 05 Oct 2009 00:00:00 +0100 2943313 http://www.medworm.com/index.php?rid=2857319&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01783.x In this study, a large, worldwide collection of F. oxysporum isolates was screened for the presence of seven SIX genes (SIX1[ndash]SIX7). The results convincingly show that identification of F. oxysporum formae speciales and races based on host-specific virulence genes can be very robust. SIX1, SIX2, SIX3 and SIX5 can be used for unambiguous identification of the forma specialis lycopersici. In addition, SIX4 can be used for the identification of race 1 strains, while polymorphisms in SIX3 can be exploited to differentiate race 2 from race 3 strains. For SIX6 and SIX7, close homologs were found in a few other formae speciales, suggesting that these genes may play a more general role in pathogenicity. Host specificity may be determined by the unique SIX genes, possibly in combination with t... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2857319 Fri, 02 Oct 2009 23:00:00 +0100 2857319 http://www.medworm.com/index.php?rid=2901511&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01806.x Enterococcus faecium has emerged as an important cause of nosocomial infections over the last two decades. We recently demonstrated collagen type I (CI) as a common adherence target for some E. faecium isolates and a significant correlation was found to exist between acm-mediated CI adherence and clinical origin. Here, we evaluated 60 diverse E. faecium isolates for their adherence to up to 15 immobilized host extracellular matrix and serum components. Adherence phenotypes were most commonly observed to fibronectin (Fn) (20% of the 60 isolates), fibrinogen (17%) and laminin (Ln) (13%), while only one or two of the isolates adhered to collagen type V (CV), transferrin or lactoferrin and none to the other host components tested. Adherence to Fn and Ln was almost exclusively restricted to cli... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2901511 Wed, 30 Sep 2009 23:00:00 +0100 2901511 http://www.medworm.com/index.php?rid=2901510&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01807.x In this study, we have found that phosphatidylcholine carrying a linoleic acid molecule or arachidonic acid molecule has the potential to kill steroid-free H. pylori. The bactericidal action of phosphatidylcholines against H. pylori was due to the lytic activity of the phosphatidylcholines themselves and not due to the lytic activity of the unsaturated fatty acids or lyso-phosphatidylcholine resulting from the hydrolysis of the phosphatidylcholines. In contrast to the steroid-free H. pylori, the organism that absorbed and glucosylated free cholesterol was unaffected by the bactericidal action of the phosphatidylcholines. Similarly, H. pylori that absorbed estrone without glucosylating it also resisted the bactericidal action of the phosphatidylcholines. The steroids absorbed by H. pylori e... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2901510 Wed, 30 Sep 2009 23:00:00 +0100 2901510 http://www.medworm.com/index.php?rid=2901509&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01808.x In conclusion, we have demonstrated the construction of a yeast strain capable of conversion of a cellulosic substrate to ethanol, representing significant progress towards the realization of processing of cellulosic biomass in a consolidated bioprocessing configuration. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2901509 Wed, 30 Sep 2009 23:00:00 +0100 2901509 http://www.medworm.com/index.php?rid=2851164&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01787.x The physiological role of NahW, the second salicylate hydroxylase of Pseudomonas stutzeri AN10, has been analysed by gene mutation and further complementation. When grown on naphthalene as a unique carbon and energy source, the nahW mutant showed a strong decrease in salicylate hydroxylase activity when compared with the wild-type strain, exhibited lower specific growth rates and accumulated salicylate in culture supernatants. Similarly, lower specific growth rates and salicylate accumulation were observed for the nahW mutant when growth on naphthalene supplemented with succinate or pyruvate. When P. stutzeri AN10 was grown in Luria[ndash]Bertani medium in the presence of salicylate, or was cultivated on minimal medium supplemented with salicylate as a unique carbon and energy source, an i... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2851164 Wed, 30 Sep 2009 23:00:00 +0100 2851164 http://www.medworm.com/index.php?rid=2842220&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01777.x The emergence of bacterial antibiotic resistance poses a significant challenge in the pursuit of novel therapeutics, making new strategies for drug discovery imperative. We have developed a yeast growth-defect phenotypic screen to help solve this current dilemma. This approach facilitates the identification and characterization of a new diphtheria toxin (DT) group, ADP-ribosyltransferase toxins from pathogenic bacteria. In addition, this assay utilizes Saccharomyces cerevisiae, a reliable model for bacterial toxin expression, to streamline the identification and characterization of new inhibitors against this group of bacterial toxins that may be useful for antimicrobial therapies. We show that a mutant of the elongation factor 2 target protein in yeast, G701R, confers resistance to all DT... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2842220 Mon, 28 Sep 2009 23:00:00 +0100 2842220 http://www.medworm.com/index.php?rid=2901512&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01805.x Entry of the peptide antibiotic microcin J25 (MccJ25) into target cells is mediated by the outer membrane receptor FhuA and the inner membrane protein SbmA. The latter also transports MccB17 into the cell cytoplasm. Comparison of MccJ25 and MccB17 revealed a tetrapeptide sequence (VGIG) common to both antibiotics. We speculated that this structural feature in MccJ25 could be a motif recognized by SbmA. To test this hypothesis, we used a MccJ25 variant in which the isoleucine in VGIG (position 13 in the MccJ25 sequence) was replaced by lysine (I13K). In experiments in which the FhuA receptor was bypassed, the substituted microcin showed an inhibitory activity similar to that of the wild-type peptide. Moreover, MccJ25 interfered with colicin M uptake by FhuA in a competition assay, while the... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2901512 Thu, 24 Sep 2009 23:00:00 +0100 2901512 http://www.medworm.com/index.php?rid=2831771&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01776.x A total of 17 Leptospira clinical strains isolated from humans in Croatia were serologically and genetically analysed. For serovar identification, the microscopic agglutination test (MAT) and pulsed-field gel electrophoresis (PFGE) were used. To identify isolates on genomic species level, PCR-based restriction fragment length polymorphism (RFLP) and real-time PCR were performed. MAT revealed the following serogroup affinities: Grippotyphosa (seven isolates), Icterohaemorrhagiae (eight isolates) and Javanica (two isolates). RFLP of PCR products from a 331-bp-long fragment of rrs (16S rRNA gene) digested with endonucleases MnlI and DdeI and real-time PCR revealed three Leptospira genomic species. Grippotyphosa isolates belonged to Leptospira kirschneri, Icterohaemorrhagiae isolates to Leptos... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2831771 Thu, 24 Sep 2009 23:00:00 +0100 2831771 http://www.medworm.com/index.php?rid=2827909&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01782.x In this study, we show that cyanide of bacterial origin may inhibit cytochrome c oxidase (CCO) of the termite respiratory chain and demonstrate that HCN-producing bacteria such as P. fluorescens can actually kill a macroscopic insect pest by cyanide poisoning. This ability of pseudomonad metabolites such as cyanide, which can bring about pest death by blocking respiration through inhibition of CCO rather than infection or predation, can potentially overcome the behavioural adaptations of social insect pests such as termites and represents an attractive option for insect pest management. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2827909 Wed, 23 Sep 2009 23:00:00 +0100 2827909 http://www.medworm.com/index.php?rid=2823667&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01771.x The RcsCDB (Rcs) phosphorelay system regulates capsule synthesis, flagella production and other cellular activities in several enteric bacteria. This system consists of three proteins: the sensor RcsC, the cognate response regulator RcsB and the histidine-containing phosphotransfer protein RcsD (YojN), which is hypothesized to act as an intermediary in the phosphotransfer from RcsC to RcsB. The rcsC gene is convergently transcribed toward rcsB, which follows rcsD in what appears to be a two-gene operon. Here, it is reported that the overproduction of the rcsB gene represses rcsD transcription, but has a weak effect on its own expression. We demonstrated that the differential rcsD and rcsB expression is due to the activity of two promoters to transcribe the rcsB gene: (1) PrcsDB located ups... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2823667 Tue, 22 Sep 2009 23:00:00 +0100 2823667 http://www.medworm.com/index.php?rid=2894044&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01794.x Deinococcus radiodurans strain R1 synthesizes a unique ketocarotenoid product named deinoxanthin. The detailed steps involved in the biosynthesis of deinoxanthin remain unresolved. A carotene ketolase homologue encoded by dr0093 was inactivated by gene mutation to verify its function in the native host D. radiodurans. Analysis of the carotenoids in the resultant mutant R1[Delta]crtO demonstrated that dr0093 encodes [gamma]-carotene ketolase (CrtO) catalysing the introduction of one keto group into the C-4 position of [gamma]-carotene derivatives to form ketolated carotenoids. The mutant R1[Delta]crtO became more sensitive to H2O2 treatment than the wild-type strain R1, indicating that the C-4 keto group is important for the antioxidant activity of carotenoids in D. radiodurans. Carotenoid ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2894044 Sun, 20 Sep 2009 23:00:00 +0100 2894044 http://www.medworm.com/index.php?rid=2875417&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01799.x The protozoan parasite Toxoplasma gondii infects its host cells through an active mechanism. In this work, we obtained evidence that host cells also play a fundamental role during the infection process. We found that previous incubation of the host cells, but not the parasites, with Dynasore, a small molecule that inhibits dynamin GTPase activity, markedly reduced the penetration of T. gondii tachyzoites into LLC-MK2 cells. In contrast, parasite adhesion to the host cell surface increased, as observed both by light and electron microscopy. Intriguingly, the few parasites internalized by Dynasore-treated cells remained in vacuoles located at the periphery of the cell, in contrast to the perinuclear localization seen in the control. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2875417 Sun, 20 Sep 2009 23:00:00 +0100 2875417 http://www.medworm.com/index.php?rid=2875416&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01801.x Examination of cell-free culture supernatants revealed that Legionella pneumophila strains secrete an endoglucanase activity. Legionella pneumophila lspF mutants were deficient for this activity, indicating that the endoglucanase is secreted by the bacterium's type II protein secretion (T2S) system. Inactivation of celA, encoding a member of the family-5 of glycosyl hydrolases, abolished the endoglucanase activity in L. pneumophila culture supernatants. The cloned celA gene conferred activity upon recombinant Escherichia coli. Thus, CelA is the major secreted endoglucanase of L. pneumophila. Mutants inactivated for celA grew normally in protozoa and macrophage, indicating that CelA is not required for the intracellular phase of L. pneumophila. The CelA endoglucanase is one of at least 25 p... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2875416 Sun, 20 Sep 2009 23:00:00 +0100 2875416 http://www.medworm.com/index.php?rid=2809556&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01775.x The ability of Eukarya, Bacteria and Archaea to perform N-glycosylation underlies the importance and possible antiquity of this post-translational protein modification. However, in contrast to the relatively well-studied eukaryal and bacterial pathways, the archaeal N-glycosylation process is less understood. To remedy this disparity, the following study has examined 56 available archaeal genomes with the aim of identifying glycosyltransferases and oligosaccharyltransferases, including those putatively catalyzing this post-translational processing event. This analysis reveals that while oligosaccharyltransferases, central components of the N-glycosylation pathway, are found across the range of archaeal phenotypes, the N-glycosylation machinery of hyperthermophilic Archaea may well rely on ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2809556 Fri, 18 Sep 2009 23:00:00 +0100 2809556 http://www.medworm.com/index.php?rid=2807250&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01784.x The Pseudomonas sp. strain ADP atzDEF operon encodes the enzymes involved in cyanuric acid mineralization, the final stage of the s-triazine herbicide atrazine degradative pathway. We have previously shown that atzDEF is under nitrogen control in both its natural host and Pseudomonas putida KT2442. Expression of atzDEF requires the divergently encoded LysR-type transcriptional regulator AtzR. Here, we take advantage of the poor induction of atzDEF in Escherichia coli to identify Pseudomonas factors involved in nitrogen control of atzDEF expression. Simultaneous production of P. putida NtrC and GlnK, along with AtzR, restored the normal atzDEF regulatory pattern. Gene expression analysis in E. coli and P. putida indicated that NtrC activates atzR expression, while the role of GlnK is to pro... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2807250 Thu, 17 Sep 2009 23:00:00 +0100 2807250 http://www.medworm.com/index.php?rid=2886198&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01792.x This study shows the usefulness of the method to determine the taxonomic and phylogenetic relationships among AAB and to study the AAB diversity of complex ecosystems. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2886198 Wed, 16 Sep 2009 23:00:00 +0100 2886198 http://www.medworm.com/index.php?rid=2886197&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01795.x Campylobacter jejuni is a significant cause of human gastroenteritis worldwide. In an attempt to further define bacterial factors that influence infectivity, Cj0596 was identified as playing a role in C. jejuni virulence. Cj0596 is a periplasmic chaperone that is similar to proteins involved in outer membrane protein (OMP) folding in other bacteria. Mutation of cj0596 caused an alteration in the levels of eight OMPs, compared with wild-type bacteria. Replacement of the cj0596 mutation with the wild-type cj0596 gene restored a wild-type OMP profile. The altered OMP profile in the cj0596 mutant was accompanied by significant changes in several virulence properties, including an increase in the ability to autoagglutinate, increased susceptibility to several antimicrobial agents, and increased... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2886197 Wed, 16 Sep 2009 23:00:00 +0100 2886197 http://www.medworm.com/index.php?rid=2886196&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01797.x Out of 17 samples collected from diverse environments, 110 bacterial isolates of varied characteristics were screened for their dibenzothiophene-desulphurizing activity. A single isolate, Eu-32, originating from a soil sample taken from the roots of a eucalyptus tree, displayed dibenzothiophene-desulphurizing activity. This isolate metabolized dibenzothiophene to 2-hydroxybiphenyl (2-HBP), as detected by HPLC, and was also able to use other organic sulphur compounds as a sole sulphur source. Based on morphological, biochemical and molecular studies, it was found that the organism belongs to the genus Rhodococcus, with a maximum of 95% identity to species in this genus for the partial sequence of the 16S rRNA gene. Isolate Eu-32 could desulphurize 0.2 mM dibenzothiophene to 2-HBP in 72 h at... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2886196 Wed, 16 Sep 2009 23:00:00 +0100 2886196 http://www.medworm.com/index.php?rid=2875418&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01796.x The two chromosomally encoded [beta]-lactamases, OXA-22 and OXA-60, from Ralstonia pickettii are inducible by [beta]-lactam molecules. Disruption of RP3 abolished induction of both [beta]-lactamases and the resistance to pH, osmolarity and survival in the stationary phase, suggesting that RP3 might be a global regulator. Interactions between RP3, OXA-22 and OXA-60 were investigated at a transcript and protein level using 5'-rapid amplification of cDNA ends experiments, real-time reverse transcription (RT)-PCR and footprinting assays. The rp3 gene was actively transcribed and the promoter sequences corresponded to a nontypical [sigma]70-type promoter. RT-PCR analysis showed that rp3 expression as well as that of the blaOXA genes was positively regulated: the level of transcripts of rp3, bla... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2875418 Wed, 16 Sep 2009 23:00:00 +0100 2875418 http://www.medworm.com/index.php?rid=2851167&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01790.x The methyl-specific restriction system of Streptomyces coelicolor A3(2) was analyzed by carrying out transformations with unmethylated and methylated pSET152 DNA. Streptomyces coelicolor was found to strongly restrict DNA methylated in vivo by the Dam, Dcm and Hsd modification systems of Escherichia coli. Hsd-modified DNA was restricted as strongly as Dam-modified DNA, even though there are significantly fewer sites on the plasmid; Dcm-modified plasmid was restricted more strongly then either Dam- or Hsd-modified DNA. Restriction of plasmid DNA modified in vitro by different methylases also showed a greater dependence on the methylated sequence than on the number of methylated sites. Streptomyces coelicolor mutants were constructed that lacked genes identified as the likely candidates for ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2851167 Tue, 15 Sep 2009 23:00:00 +0100 2851167 http://www.medworm.com/index.php?rid=2800056&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01772.x This study aimed to identify and characterize genes encoding glucansucrase/glucosyltransferase (GTF) and fructansucrases/fructosyltransferase (FTF) enzymes from genomic DNA of 'rare' Indonesian exopolysaccharide-producing LAB. From a total of 63 exopolysaccharide-producing LAB isolates obtained from foods, beverages and environmental samples, 18 isolates showing the most slimy and mucoid colony morphologies on sucrose were chosen for further study. By comparing bacterial growth on De Man, Rogosa and Sharpe (MRS)-sucrose with that on MRS-raffinose, and using the results of a previous PCR screening study with degenerate primer pairs targeting the conserved catalytic domain of GTFs, various strains were identified as producers of fructan (13), of glucan only (five) or as potential producers o... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2800056 Tue, 15 Sep 2009 23:00:00 +0100 2800056 http://www.medworm.com/index.php?rid=2796145&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01764.x Noncatalytic carbohydrate-binding modules (CBMs), which are found in a variety of carbohydrate-degrading enzymes, have been grouped into sequence-based families. CBMs, by recruiting their appended enzymes onto the surface of the target substrate, potentiate catalysis particularly against insoluble substrates. Family 6 CBMs (CBM6s) display unusual properties in that they present two potential ligand-binding sites termed clefts A and B, respectively. Cleft B is located on the concave surface of the [beta]-sandwich fold while cleft A, the more common binding site, is formed by the loops that connect the inner and the outer [beta]-sheets. Here, we report the biochemical properties of CBM6-1 from Cellvibrio mixtus CmCel5A. The data reveal that CBM6-1 specifically recognizes [beta]1,3-glucans th... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2796145 Mon, 14 Sep 2009 23:00:00 +0100 2796145 http://www.medworm.com/index.php?rid=2930653&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01789.x We sampled five Achnatherum sibiricum populations and documented the distribution and abundance of endophytes. In total, 438 fungal isolates were obtained. They were classified into 11 morphotypes based on growth rate and morphological characters including colonial morphology, the production of conidiogenous cells, conidial size and dimension on potato dextrose agar medium. Both tub2 and actG sequences identified only a single product in all representative isolates from three dominant morphotypes. All sequences fell in the same main clade, including Neotyphodium gansuense and Neotyphodium gansuense var. inebrians from another Achnatherum species in North China, Achnatherum inebrians, and Neotyphodium guerinii from European grasses Melica ciliate and Melica transsilvanica. Based on both mor... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2930653 Fri, 11 Sep 2009 00:00:00 +0100 2930653 http://www.medworm.com/index.php?rid=2785596&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01766.x The TON_0002 gene, which is in close proximity to the DNA polymerase locus in Thermococcus onnurineus NA1, has been shown to encode an inorganic pyrophosphatase. Its genomic position and function suggest a role for pyrophosphate hydrolysis during DNA polymerization. This is the first report of an inorganic pyrophosphatase belonging to the haloacid dehalogenase superfamily, in which unique residues in motif I and II have been replaced with Trp and Gly, respectively. The optimum pyrophosphatase activity of the recombinant enzyme occurred at pH 6, and it displayed an absolute dependence on divalent metal ions, among which Ni2+ was the most efficient. The site-specific mutation of the Gly residue in motif II to Ala or Ser residue exhibited only a slight change in the enzymatic activity and the... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2785596 Thu, 10 Sep 2009 23:00:00 +0100 2785596 http://www.medworm.com/index.php?rid=2871371&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01788.x Cellulosomes are cellulolytic complexes produced by anaerobic bacteria, and are composed of a scaffolding protein and several catalytic components. The complexes are formed by highly specific interactions of one of the reiterated cohesin modules of the scaffolding protein with a dockerin module of the catalytic components. The affinities of a dockerin module of Clostridium thermocellum CelJ (Cel9D-Cel44A) for several cohesin modules from C. thermocellum and Clostridium josui scaffolding proteins were quantitatively measured by surface plasmon resonance analysis. The recombinant CelJ dockerin-containing protein interacted with three recombinant C. josui cohesin proteins as well as recombinant C. thermocellum cohesin proteins beyond the so-called 'species specificity' of the dockerin and coh... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2871371 Wed, 09 Sep 2009 23:00:00 +0100 2871371 http://www.medworm.com/index.php?rid=2851165&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2009.01786.x In this study, we showed that this locus, named ahs, codes for two proteins (AhsA and AhsB) that exhibit characteristics of a trimeric autotransporter adhesin. Sequence analysis of AhsA showed the presence of 21 collagen-binding motifs in the protein. Collagen-binding assays showed that M. haemolytica A1 binds to collagen in a dose-dependent manner. This binding activity is trypsin sensitive and can be inhibited by anti-AhsA antibody. AhsB is the cognate transporter for AhsA. The C-terminal of AhsB showed highly conserved amino acids typical of trimeric autotransporters. Experimental data showed that the C-terminal 120 amino acids of AhsB could indeed form trimeric molecules. Western immunoblots showed the presence of anti-AhsA antibodies in the sera of calves that had been challenged with... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=2851165 Tue, 08 Sep 2009 23:00:00 +0100 2851165