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, 09 Feb 2012 21:34:59 +0100 http://www.medworm.com/index.php?rid=5674650&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02521.x In conclusion, the iph operon is negatively autoregulated by the binding of IphR to the operator region, and this repression is released by the presence of IPA.© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5674650 Fri, 10 Feb 2012 01:55:29 +0100 5674650 http://www.medworm.com/index.php?rid=5664641&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02517.x AbstractStreptomyces coelicolor produces spore‐forming aerial hyphae after a period of vegetative growth. These aerial structures are decorated with a hydrophobic coating of rodlets consisting of chaplins and rodlins. Here we show that rodlins and the surface‐active peptide SapB are essential for development during growth in a medium with high osmolarity. To this end, both vegetative and aerial hyphae secrete SapB, whereas rodlins are only secreted by the spore‐forming aerial hyphae.© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664641 Tue, 07 Feb 2012 01:50:54 +0100 5664641 http://www.medworm.com/index.php?rid=5664652&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02518.x This study demonstrated that Ich could vector E. ictaluri to channel catfish.© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664652 Mon, 06 Feb 2012 05:00:00 +0100 5664652 http://www.medworm.com/index.php?rid=5664651&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02519.x AbstractHeme is a key molecule for Staphylococcus aureus and is involved in many aspects of oxidative metabolism. Crucially, heme is required for the activity of the cytochromes of the electron transport chain. S. aureus is able to obtain heme either through biosynthesis or through acquisition from the host. Clinically persistent ‘small colony variant’ (SCV) forms of S. aureus are frequently deficient for heme biosynthesis, and disruption of the hemB gene produces stable heme auxotrophic strains that reproduce many SCV phenotypes. We sought to address the role of heme transport in SCVs by deleting components of the two described heme import systems, the iron‐regulated surface determinant (Isd) and heme transport system (Hts) in wild‐type S. aureus and hemB mutant backgrounds. Analy... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664651 Mon, 06 Feb 2012 05:00:00 +0100 5664651 http://www.medworm.com/index.php?rid=5664645&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02520.x AbstractChlamydophila pneumoniae, an obligate intracellular human pathogen, causes respiratory tract infections. The most common techniques used for the serological diagnosis of C. pneumoniae infections are microimmunofluorescence tests and commercial serological ELISA tests; these are based on the detection of antibodies against whole chlamydial elementary bodies and lipopolysaccharide/outer membrane protein, respectively. Identification of more specific and highly immunodominant antigens is essential for the development of new serodiagnostic assays. To identify novel specific antigens from C. pneumoniae, we screened 455 genes with unknown function in the genome of C. pneumoniae J138. Extracts of Saccharomyces cerevisiae cells expressing GFP‐tagged C. pneumoniae proteins were subjected ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664645 Mon, 06 Feb 2012 05:00:00 +0100 5664645 http://www.medworm.com/index.php?rid=5664643&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02515.x AbstractThe pathogenic fungus Ascosphaera apis is ubiquitous in honey bee populations. We used the draft genome assembly of this pathogen to search for polymorphic intergenic loci that could be used to differentiate haplotypes. Primers were developed for five such loci, and the species‐specificities were verified using DNA from nine closely related species. The sequence variation was compared among 12 A. apis isolates at each of these loci, and two additional loci, the internal transcribed spacer of the ribosomal RNA (ITS) and a variable part of the elongation factor 1α (Ef1α). The degree of variation was then compared among the different loci, and three were found to have the greatest detection power for identifying A. apis haplotypes. The described loci can help to resolve strain dif... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664643 Mon, 06 Feb 2012 05:00:00 +0100 5664643 http://www.medworm.com/index.php?rid=5664642&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02516.x This study further analyzes lipA gene expression and demonstrates that the RNA polymerase σ54 is involved in the transcription. Purified LipR has an ATPase activity that is stimulated by presence of lipA promoter DNA. Surface plasmon resonance measurements with purified and in vitro phosphoryled LipR reveal that phosphorylation of LipR is required for specific binding to the upstream activating sequence of the lipA promoter. Furthermore, mass spectrometric analysis combined with mutagenesis demonstrates that Asp52 is the phosphorylated aspartate. This analysis exposes LipR as a prominent member of the growing family of bacterial enhancer‐binding proteins.© 2012 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved (Source: FEMS Mic... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5664642 Mon, 06 Feb 2012 05:00:00 +0100 5664642 http://www.medworm.com/index.php?rid=5644292&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02514.x (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5644292 Tue, 31 Jan 2012 20:33:10 +0100 5644292 http://www.medworm.com/index.php?rid=5644294&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02512.x AbstractElectromagnetic irradiation (EMI) of 51.8 and 53.0 GHz frequencies with low‐intensity (the flux capacity of 0.06 mW cm−2) and with exposure during 1 h markedly decreased the energy‐dependent H+ and K+ transport across the membranes of Enterococcus hirae ATCC9790. After EMI, a significant decrease of the overall and N,N’‐dicyclohexylcarbodiimide (DCCD) sensitive ATPase activity of the membrane vesicles occurred as well. They were considerably lowered with 53.0 GHz frequency. EMI in combination with different antibiotics, such as ceftriaxone and kanamycin in their minimal inhibitory concentrations (100 μM and 200 μM, correspondingly), had enhanced effects on the bacterial cell growth and the changes in their membrane transport properties. Especially, total H+ efflux was m... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5644294 Tue, 31 Jan 2012 05:00:00 +0100 5644294 http://www.medworm.com/index.php?rid=5644293&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02513.x AbstractIn Saccharomyces cerevisiae, Nce102 encodes a 173 amino acid transmembrane protein, which acts as a key player in eisosome assembly and plasma membrane organization. Here we describe the characterization of Nce102 homologue in the human pathogen, Aspergillus fumigatus. Our results demonstrated that AfuNce102 is continuously expressed during fungal growth. In addition, microscopic examination of an AfuNce102‐GFP expressing transformant confirmed the localization of the fusion protein to the endoplasmic reticulum with higher density fluorescence at the tip of the mycelium. During conidiogenesis, the protein was localized to the conidiophores and the conidia. Abnormal conidiation of AfuNce102 deletion mutant suggests a potential role for AfuNce102 in sporulation process. (Source: FE... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5644293 Tue, 31 Jan 2012 05:00:00 +0100 5644293 http://www.medworm.com/index.php?rid=5635978&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02511.x In this study, we deleted all three pyruvate decarboxylase (PDC) genes, which encode enzymes that function upstream of ACS1 in the PAA pathway. Results suggest PDC1 is required for lipid accumulation in the aerial mycelia, and deletion of PDC1 resulted in highly wettable mycelia. However, the total amount of lipids in the PDC1 deletion mutants was similar to that of the wild‐type strain, likely due to compensatory lipid production processes in the embedded mycelia. PDC1 was expressed both in the aerial and embedded mycelia, whereas ACS1 was observed only in the aerial mycelia in a PDC1‐dependent manner. PDC1 is also involved in vegetative growth of embedded mycelia in G. zeae, possibly through initiating the ethanol fermentation pathway. Thus, PDC1 may function as a key metabolic enzym... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5635978 Sat, 28 Jan 2012 02:20:39 +0100 5635978 http://www.medworm.com/index.php?rid=5635979&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02510.x AbstractPyridoxine is converted to succinic semialdehyde, acetate, ammonia, and CO2 through the actions of eight enzymes. The genes encoding the enzymes occur as a cluster on the chromosomal DNA of Mesorhizobium loti, a symbiotic nitrogen‐fixing bacterium. Here, it was found that disruption of the mll6786 gene, which is located between the genes encoding the first and eighth enzymes of the pathway, caused constitutive expression of the eight enzymes. The protein encoded by the mll6786 gene is a member of the GntR family and is designated as PyrR. PyrR comprises 223 amino acid residues, and is a dimeric protein with a subunit molecular mass of 25 kDa. The purified PyrR with a C‐terminal His6‐tag could bind to an intergenic 67‐bp DNA region, which contains a palindrome sequence and a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5635979 Wed, 25 Jan 2012 05:00:00 +0100 5635979 http://www.medworm.com/index.php?rid=5625234&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02504.x AbstractBacillus thuringiensis Cry1Ac toxin shares structurally five conserved blocs with the other delta‐endotoxins. In order to study the role of some amino acids belonging to these regions, two mutations, Y229P and F603S, have been introduced separately and respectively in blocs 2 and 5. The resulting mutant proteins Cry1Ac'1 and Cry1Ac'3 were affected in their stability and crystallization. Both of them lost their toxicity to the Lepidopteran larvae Ephestia kuehniella. Unlike Cry1Ac'1, Cry1Ac'3 becomes very sensitive to proteases. Accordingly, 3‐Dimential structures of the two mutants have been studied. The obtained models showed that both of the residuesY229, located near the bottom of the α7 helix, and F603, located in the core of the domain III, are involved in hydrophobic int... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625234 Wed, 25 Jan 2012 03:49:48 +0100 5625234 http://www.medworm.com/index.php?rid=5674652&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02505.x AbstractSorbitol‐fermenting Escherichia coli O157:NM (SF O157) is an emerging pathogen suggested to be more virulent than nonsorbitol‐fermenting Escherichia coli O157:H7 (NSF O157). Important virulence factors are the Shiga toxins (stx), encoded by stx1 and/or stx2 located within prophages integrated in the bacterial genome. The stx genes are expressed from pR′ as a late protein, and anti‐terminator activity from the Q protein is necessary for read through of the late terminator tR′ and activation of pR′. We investigated the regulation of stx2EDL933 expression at the genomic level in 17 Norwegian SF O157. Sequencing of three selected SF O157 strains revealed that the anti‐terminator q gene and genes upstream of stx2EDL933 were identical or similar to the ones observed in the ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5674652 Mon, 23 Jan 2012 05:00:00 +0100 5674652 http://www.medworm.com/index.php?rid=5674651&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02502.x In this study, the genes encoding the surface proteins IsdA,IsdB, and IsdH were inactivated in order to determine their combined role. The triple mutant was found to have no defect in growth under any conditions of iron limitation tested. Also using a mouse septic arthritis model of S. aureus systemic disease, no significant difference in bacterial load was observed for the triple mutant, compared with its otherwise isogenic parent. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5674651 Mon, 23 Jan 2012 05:00:00 +0100 5674651 http://www.medworm.com/index.php?rid=5625242&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02509.x AbstractAn Agrobacterium tumefaciens membrane‐bound ferritin (mbfA) mutant was generated to assess the physiological functions of mbfA in response to iron and hydrogen peroxide (H2O2) stresses. Wild‐type and the mbfA mutant showed similar growth under high‐ and low‐iron conditions. The mbfA mutant was more sensitive to H2O2 than wild‐type. Expression of a functional mbfA gene could complement the H2O2‐hypersensitive phenotype of the mbfA mutant and a rhizobial iron regulator (rirA) mutant, suggesting that MbfA protects cells from H2O2 toxicity by sequestering intracellular free iron, thus preventing the Fenton reaction. The expression of mbfA could be induced in response to iron and to H2O2 treatment. The iron response regulator (irr) also acted as a repressor of mbfA expressio... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625242 Mon, 23 Jan 2012 05:00:00 +0100 5625242 http://www.medworm.com/index.php?rid=5625241&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02507.x AbstractLuminous marine bacteria usually emit bluish‐green light with a peak emission wavelength (λmax) at about 490 nm. Some species belonging to the genus Photobacterium are exceptions, producing an accessory blue fluorescent protein (lumazine protein: LumP) that causes a blue shift, from λmax ≈ 490 to λmax ≈ 476 nm. However, the incidence of blue‐shifted light emission or the presence of accessory fluorescent proteins in bacteria of the genus Vibrio has never been reported. From our spectral analysis of light emitted by 16 luminous strains of the genus Vibrio, it was revealed that most strains of Vibrio azureus emit a blue‐shifted light with a peak at approximately 472 nm, whereas other Vibrio strains emit light with a peak at around 482 nm. Therefore, we investigated ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625241 Mon, 23 Jan 2012 05:00:00 +0100 5625241 http://www.medworm.com/index.php?rid=5625240&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02508.x AbstractThe correlation between the taxonomic composition of Alphaproteobacteria, Burkholderia and nitrogen fixers associated with the lichen Lobaria pulmonaria and the geographical distribution of the host was studied across four sites in Europe. Results proved that the diversity of Alphaproteobacteria is affected by geography, while those of Burkholderia and nitrogen fixers were mostly driven by local habitat. This difference indicates a higher stability of the association between Alphaproteobacteria and the lichen host. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625240 Mon, 23 Jan 2012 05:00:00 +0100 5625240 http://www.medworm.com/index.php?rid=5625239&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02506.x AbstractThe heterogeneity of cell populations and the influence of stochastic noise might be important issues for the molecular analysis of cellular reprogramming at the systems level. Here, we show that in Physarum polycephalum, the expression patterns of marker genes correlate with the fate decision of individual multinucleate plasmodial cells that had been exposed to a differentiation‐inducing photo‐stimulus. For several hours after stimulation, the expression kinetics of PI‐3‐kinase, piwi, and pumilio orthologs and other marker genes were qualitatively similar in all stimulated cells but quantitatively different in those cells that subsequently maintained their proliferative potential and failed to differentiate accordingly. The results suggest that the population of nuclei in ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625239 Mon, 23 Jan 2012 05:00:00 +0100 5625239 http://www.medworm.com/index.php?rid=5625238&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02505.x AbstractSorbitol‐fermenting Escherichia coli O157:NM (SF O157) is an emerging pathogen suggested to be more virulent than non‐sorbitol‐fermenting Escherichia coli O157:H7 (NSF O157). Important virulence factors are the Shiga toxins (Stx), encoded by stx1 and/or stx2 located within prophages integrated in the bacterial genome. The stx genes are expressed from pR’ as a late protein, and anti‐terminator activity from the Q protein is necessary for read through of the late terminator tR’ and activation of pR’.We investigated the regulation of stx2EDL933 expression at the genomic level in 17 Norwegian SF O157. Sequencing of three selected SF O157 strains revealed that the anti‐terminator q gene and genes upstream of stx2EDL933 were identical or similar to the ones observed in th... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625238 Mon, 23 Jan 2012 05:00:00 +0100 5625238 http://www.medworm.com/index.php?rid=5625237&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02501.x AbstractBiodegradation of polycyclic aromatic hydrocarbons (PAHs) in soils has been linked to history of exposure to PAHs and prevailing environmental conditions. This work assessed the capacity of indigenous microorganisms in soils collected in Livingstone Island (South Shetlands Islands, Antarctica) with no history of pollution (∑PAHs: 0.2 – 1.16 ng g−1dw) to degrade 14C‐phenanhthrene at 4°C, 12°C and 22°C. The study provides evidence of the presence of phenanthrene‐degrading microorganisms in all studied soils. Generally, the percentage of 14C‐phenanhthrene mineralised increased with increasing temperature. The highest extent of 14C‐phenanhthrene mineralisation (47.93%) was observed in the slurried system at 22°C. This work supports findings of the presence of PAH degr... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625237 Mon, 23 Jan 2012 05:00:00 +0100 5625237 http://www.medworm.com/index.php?rid=5625236&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02503.x In this study, we report the first genome‐wide identification of asRNA constructs for essential genes in Escherichia coli. We screened 250,000 library transformants for conditional growth‐inhibitory recombinant clones from two shot‐gun genomic libraries of E. coli using a paired‐termini expression vector (pHN678). After sequencing plasmid inserts of 675 confirmed inducer‐sensitive cell clones, we identified 152 separate asRNA constructs of which 134 inserts came from essential genes while 18 originated from non‐essential genes (but share operons with essential genes). Among the 79 individual essential genes silenced by these asRNA constructs, 61 genes (77%) engage in processes related to protein synthesis. The cell‐based assays of an asRNA clone targeting fusA (encoding elong... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625236 Mon, 23 Jan 2012 05:00:00 +0100 5625236 http://www.medworm.com/index.php?rid=5625235&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02502.x In this study the genes encoding the surface proteins IsdA, IsdB and IsdH were inactivated in order to determine their combined role. The triple mutant was found to have no defect in growth under any conditions of iron limitation tested. Also using a mouse septic arthritis model of S. aureus systemic disease, no significant difference in bacterial load was observed for the triple mutant, compared to its otherwise isogenic parent. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5625235 Mon, 23 Jan 2012 05:00:00 +0100 5625235 http://www.medworm.com/index.php?rid=5604503&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02500.x AbstractThe emergence of antibiotic resistance requires new therapeutic approaches for combating persistent bacterial infection. An alternative approach is the regulation of bacterial virulence instead of growth suppression that can readily lead to drug resistance. The virulence of the opportunistic human pathogen Pseudomonas aeruginosa depends on a large number of extracellular factors and biofilm formation. Thirty‐one natural and synthetic indole derivatives were screened to identify 7‐fluoroindole (7FI) as the compound inhibiting biofilm formation and blood hemolysis without inhibiting the growth of planktonic P. aeruginosa cells. Moreover, 7FI markedly reduced the production of quorum sensing (QS)‐regulated virulence factors including 2‐heptyl‐3‐hydroxy‐4(1H)‐quinolone,... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5604503 Thu, 19 Jan 2012 02:46:36 +0100 5604503 http://www.medworm.com/index.php?rid=5604504&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02499.x In this study, it was demonstrated that in Vibrio fischeri, CsrA causes an increase in the transcript levels of a downstream quorum‐sensing regulatory gene, luxR, which does not exist in the V. cholerae system. In V. fischeri, the increase in luxR transcripts caused by CsrA does not depend on the LitR transcriptional activator nor does the CsrA effect seem to occur through the global regulator cAMP‐CRP. Thus there appears to be more than one mechanism whereby the CsrA and quorum‐sensing pathways integrate regulatory outputs in Vibrios. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5604504 Tue, 17 Jan 2012 05:00:00 +0100 5604504 http://www.medworm.com/index.php?rid=5594021&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02496.x AbstractNearly all free living bacteria carry toxin‐antitoxin (TA) systems on their genomes, through which cell growth and death are regulated. Toxins target a variety of essential cellular functions, including DNA replication, translation, and cell division. Here we identified a novel toxin, YgfX, on the E. coli genome. The toxin, consisting of 135 residues, is composed of the N‐terminal membrane domain, which encompasses two transmembrane segments, and the C‐terminal cytoplasmic domain. Upon YgfX expression, the cells were initially elongated and then the middle portion of the cells became inflated to form a lemon‐shape. YgfX was found to interact with MreB and FtsZ, two essential cytoskeletal proteins in E. coli. The cytoplasmic domain [YgfX(C)], was found to be responsible for ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5594021 Mon, 16 Jan 2012 04:17:49 +0100 5594021 http://www.medworm.com/index.php?rid=5644295&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02496.x AbstractNearly all free‐living bacteria carry toxin–antitoxin (TA) systems on their genomes, through which cell growth and death are regulated. Toxins target a variety of essential cellular functions, including DNA replication, translation, and cell division. Here, we identified a novel toxin, YgfX, on the Escherichia coli genome. The toxin, consisting of 135 residues, is composed of the N‐terminal membrane domain, which encompasses two transmembrane segments, and the C‐terminal cytoplasmic domain. Upon YgfX expression, the cells were initially elongated and then the middle portion of the cells became inflated to form a lemon shape. YgfX was found to interact with MreB and FtsZ, two essential cytoskeletal proteins in E. coli. The cytoplasmic domain [YgfX(C)] was found to be respon... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5644295 Thu, 12 Jan 2012 05:00:00 +0100 5644295 http://www.medworm.com/index.php?rid=5594023&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02498.x AbstractBiofilm formation in Vibrio cholerae is in part regulated by norspermidine, a polyamine synthesized by the enzyme carboxynorspermidine decarboxylase (NspC). The absence of norspermidine in the cell leads to a marked reduction in V. cholerae biofilm formation by an unknown mechanism. In this work, we show that overexpression of nspC results in large increases in biofilm formation and vps gene expression as well as a significant decrease in motility. Interestingly, increased NspC levels do not lead to increased concentrations of norspermidine in the cell. Our results show that NspC levels inversely regulate biofilm and motility and implicate the presence of an effective feedback mechanism maintaining norspermidine homeostasis in V. cholerae. Moreover, we provide evidence that NspC an... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5594023 Thu, 12 Jan 2012 05:00:00 +0100 5594023 http://www.medworm.com/index.php?rid=5594022&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2012.02497.x AbstractWe determined the complete mitochondrial genome sequence of the compactin‐producing fungus Penicillium solitum strain 20‐01. The 28601‐base pair circular‐mapping DNA molecule encodes a characteristic set of mitochondrial proteins and RNA genes and is intron‐free. All 46 protein‐ and RNA‐encoding genes are located on one strand and apparently transcribed in one direction. Comparative analysis of this mtDNA and previously sequenced but unannotated mitochondrial genomes of several medically and industrially important species of the Aspergillus/Penicillium group revealed their extensive similarity in terms of size, gene content and sequence homology, which is also reflected in the almost perfect conservation of mitochondrial gene order in Penicillium and Aspergillus. Phyl... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5594022 Thu, 12 Jan 2012 05:00:00 +0100 5594022 http://www.medworm.com/index.php?rid=5569692&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02495.x AbstractIn the present work, the adhesion of 43 human lactobacilli isolates to mucin has been studied. The most adherent strains were selected and their capacities to adhere to three epithelial cell lines were studied. All intestinal strains and one vaginal isolate adhered to HT‐29 cells. The latter was the most adherent to Caco‐2 cells, although two of the intestinal isolates were also highly adherent. Moreover, five out of the eight strains strongly adhered to HeLa cells. The binding of an Actinomyces neuii clinical isolate to HeLa cells was enhanced by two of the lactobacilli and by their secreted proteins, while those of another two strains almost abolished it. None of the strains were able to interfere with the adhesion of Candida albicans to HeLa cells. The components of the extr... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569692 Sat, 07 Jan 2012 08:34:50 +0100 5569692 http://www.medworm.com/index.php?rid=5604506&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02493.x AbstractThe need for improved rapid diagnostic tests for tuberculosis disease has prompted interest in the volatile organic compounds (VOCs) emitted by Mycobacterium tuberculosis complex bacteria. We have investigated VOCs emitted by Mycobacterium bovis BCG grown on Lowenstein–Jensen media using selected ion flow tube mass spectrometry and thermal desorption‐gas chromatography‐mass spectrometry. Compounds observed included dimethyl sulphide, 3‐methyl‐1‐butanol, 2‐methyl‐1‐propanol, butanone, 2‐methyl‐1‐butanol, methyl 2‐methylbutanoate, 2‐phenylethanol and hydrogen sulphide. Changes in levels of acetaldehyde, methanol and ammonia were also observed. The compounds identified are not unique to M. bovis BCG, and further studies are needed to validate their diagnos... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5604506 Fri, 06 Jan 2012 05:00:00 +0100 5604506 http://www.medworm.com/index.php?rid=5604505&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02495.x AbstractIn the present work, the adhesion of 43 human lactobacilli isolates to mucin has been studied. The most adherent strains were selected, and their capacities to adhere to three epithelial cell lines were studied. All intestinal strains and one vaginal isolate adhered to HT‐29 cells. The latter was the most adherent to Caco‐2 cells, although two of the intestinal isolates were also highly adherent. Moreover, five of the eight strains strongly adhered to HeLa cells. The binding of an Actinomyces neuii clinical isolate to HeLa cells was enhanced by two of the lactobacilli and by their secreted proteins, while those of another two strains almost abolished it. None of the strains were able to interfere with the adhesion of Candida albicans to HeLa cells. The components of the extrace... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5604505 Fri, 06 Jan 2012 05:00:00 +0100 5604505 http://www.medworm.com/index.php?rid=5569694&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02494.x AbstractBoth ThyA and ThyX proteins catalyze the transfer of the methyl group from methylenetetrahydrofolate (CH2H4‐folate) to dUMP, forming dTMP. To estimate the relative steady state expression levels of ThyA and ThyX, Western blot analysis was performed using ThyA or ThyX antiserum on total protein from the wild‐type, ΔthyX, and thyX complemented strains of Corynebacterium glutamicum.The level of ThyA decreased gradually during the stationary growth phase, but that of ThyX was maintained steadily. While the expression level of ThyA in a ΔsigB strain was comparable to that of the wild‐type, the level of ThyX was significantly diminished in the deletion mutant and restored to that of wild‐type in the complemented strain, indicating that the level of ThyX was regulated by SigB. G... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569694 Fri, 06 Jan 2012 05:00:00 +0100 5569694 http://www.medworm.com/index.php?rid=5569693&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02493.x AbstractThe need for improved rapid diagnostic tests for tuberculosis disease has prompted interest in the volatile organic compounds (VOCs) emitted by Mycobacterium tuberculosis complex bacteria. We have investigated VOCs emitted by Mycobacterium bovis BCG grown on Lowenstein Jensen media using selected ion flow tube mass spectrometry and thermal desorption‐gas chromatography‐mass spectrometry. Compounds observed included dimethyl sulphide, 3‐methyl‐1‐butanol, 2‐methyl‐1‐propanol, butanone, 2‐methyl‐1‐butanol, methyl 2‐methylbutanoate, 2‐phenylethanol and hydrogen sulphide. Changes in levels of acetaldehyde, methanol and ammonia were also observed. The compounds identified are not unique to M. bovis BCG and further studies are needed to validate their diagnostic ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569693 Fri, 06 Jan 2012 05:00:00 +0100 5569693 http://www.medworm.com/index.php?rid=5542483&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02492.x AbstractStreptococcus mutans, a primary dental pathogen, has a remarkable capacity to scavenge nutrients from the oral biofilm for its survival. Cystine is an amino acid dimer formed by the oxidation of two cysteine residues that is required for optimal growth, whereas S. mutans modulates L‐cystine uptake via two recently identified transporters designated TcyABC and TcyDEFGH, which have not been fully characterized. Using a non‐polar tcyABC‐deficient mutant (SmTcyABC), here we report that L‐cystine uptake is drastically diminished in the mutant, whereas its ability to grow is severely impaired under L‐cystine starvation conditions, relative to wild type. A substrate competition assay showed that L‐cystine uptake by the TcyABC transporter was strongly inhibited by DL‐cystathi... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5542483 Mon, 26 Dec 2011 14:20:45 +0100 5542483 http://www.medworm.com/index.php?rid=5534247&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02486.x In this study, the detection specificity was evaluated with respect to probe‐target sequence similarity using genomic DNAs of four Pseudomonas strains. Genome fragments averaging 2000 bp were found to be specific enough to discriminate 85‐90% similarity under highly stringent hybridization conditions. Such stringent conditions compromised signal intensities, however, specific signals remained detectable at the highest stringency (at 75°C hybridization) with negligible false negatives. These results suggest that, without any probe design or selection, genomic fragments can provide a reasonable specificity for microbial diagnostics or species delineation by DNA‐DNA similarities. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5534247 Fri, 23 Dec 2011 15:03:28 +0100 5534247 http://www.medworm.com/index.php?rid=5542487&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02488.x AbstractIn the present study, a total of 25 endophytic fungi were successfully isolated from the inner bark of Taxus baccata grown in Iran by the aseptic technique. Genomic DNA was extracted from isolated endophytic fungi and subjected to polymerase chain reaction (PCR) analysis for the presence of the Taxus taxadiene synthase (ts) gene, which encodes the enzyme catalyzing the first committed step of taxol biosynthesis. Four out of 25 isolated endophytic fungi isolates showed PCR positive for the ts gene. Subsequently, taxol and 10‐deacetyl baccatin III (10‐DAB III) were extracted from culture filtrates and mycelia of the PCR positive isolates, and analyzed by high‐performance liquid chromatography and mass spectrometry (HPLC/MS). The analysis showed that one isolate (SBU‐16) produ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5542487 Fri, 23 Dec 2011 05:00:00 +0100 5542487 http://www.medworm.com/index.php?rid=5542486&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02489.x In this study, a novel oligonucleotide probe targeting C. velia's small subunit ribosomal RNA was designed. To enable usage of this probe as a detection tool, a fluorescence in situ hybridization (FISH) protocol was optimised. The results obtained showed that when used in combination, the C. velia CV1 probe and optimised FISH protocol enabled efficient detection of C. velia in culture. This new technique will allow a better understanding of the ecological role of C. velia within the coral microhabitat. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5542486 Fri, 23 Dec 2011 05:00:00 +0100 5542486 http://www.medworm.com/index.php?rid=5542485&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02490.x AbstractClinical management of patients undergoing treatment of oropharyngeal candidiasis with azole antifungals can be impaired by azole resistance. High‐level azole resistance is often caused by the overexpression of Candida albicans efflux pump Cdr1p. Inhibition of this pump therefore represents a target for combination therapies that reverse azole‐resistance. We assessed the therapeutic potential of the D‐octapeptide derivative RC21v3, a Cdr1p inhibitor, in the treatment of murine oral candidiasis caused by either the azole‐resistant C. albicans clinical isolate MML611 or its azole‐susceptible parental strain MML610. RC21v3, fluconazole (FLC), or a combination of both drugs, were administered orally to immunosuppressed ICR mice at 3, 24, and 27 h after oral inoculation with C... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5542485 Fri, 23 Dec 2011 05:00:00 +0100 5542485 http://www.medworm.com/index.php?rid=5542484&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02491.x AbstractCTBT (7‐chlorotetrazolo[5,1‐c]benzo[1,2,4]triazine) causes intracellular superoxide production, oxidative stress and enhances the susceptibility of Saccharomyces cerevisiae, Candida albicans and C. glabrata cells to cycloheximide, 5‐fluorocytosine and azole antimycotic drugs. Here we demonstrate the antifungal activity of CTBT against 14 tested filamentous fungi. CTBT prevented spore germination and mycelial proliferation of Aspergillus niger and the pathogenic A. fumigatus. The action of CTBT is fungicidal. CTBT increased the formation of reactive oxygen species in fungal mycelium as detected by 2′,7′‐dichlorodihydrofluorescein diacetate and reduced the radial growth of colonies in dose dependent manner. Co‐application of CTBT and itraconazole led to complete inhibit... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5542484 Fri, 23 Dec 2011 05:00:00 +0100 5542484 http://www.medworm.com/index.php?rid=5569697&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02486.x In this study, the detection specificity was evaluated with respect to probe‐target sequence similarity using genomic DNAs of four Pseudomonas strains. Genome fragments averaging 2000 bp were found to be specific enough to discriminate 85–90% similarity under highly stringent hybridization conditions. Such stringent conditions compromised signal intensities; however, specific signals remained detectable at the highest stringency (at 75 °C hybridization) with negligible false negatives. These results suggest that, without any probe design or selection, genomic fragments can provide a reasonable specificity for microbial diagnostics or species delineation by DNA–DNA similarities. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569697 Thu, 22 Dec 2011 05:00:00 +0100 5569697 http://www.medworm.com/index.php?rid=5534249&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02487.x AbstractThe membrane‐bound alcohol dehydrogenase of Gluconacetobacter diazotrophicus contains one pyrroloquinoline quinone moiety (PQQ), one [2Fe‐2S] cluster and four c‐type cytochromes. Here, we describe a novel and inactive enzyme. ADHi, similarly to ADHa is a heterodimer of 72 and 44 kDa subunits and contains the expected prosthetic groups. However, ADHa showed a threefold molecular mass as compared to ADHi. Noteworthy, the PQQ, the [2Fe‐2S] and most of the cytochromes in purified ADHi is in the oxidized form, contrasting with ADHa where the PQQ‐semiquinone is detected and the [2Fe‐2S] cluster as well as the cytochromes c remained fully reduced after purification. Reduction kinetics of the ferricyanide‐oxidized enzymes showed that, while ADHa was brought back by ethanol to... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5534249 Thu, 22 Dec 2011 05:00:00 +0100 5534249 http://www.medworm.com/index.php?rid=5534248&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02485.x In this study, we attempt to resolve the confusion caused by the apparent duplication of the species N. weaveri (with different type strains) using whole genome shotgun sequencing. We also sought to gain insight into the genetic characteristics of N. weaveri by conducting comparative genomics. On the basis of genomic similarities revealed through a comparative genomic study, we propose that N. weaveri Andersen et al. 1993 should be re‐classified as a later heterotypic synonym of N. weaveri Holmes et al. 1993. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5534248 Thu, 22 Dec 2011 05:00:00 +0100 5534248 http://www.medworm.com/index.php?rid=5512987&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02440.x AbstractThe present study was conducted to test the ability of probiotic lactobacilli to alter age‐related immunosenescence in host animals. Senescence‐accelerated mouse prone 1 mice were orally fed heat‐killed Lactobacillus gasseriTMC0356 (TMC0356) for 4 and 8 weeks at dosages of 10 mg day−1 after a 16‐week period of prefeeding with a standard diet. After 4 and 8 weeks of TMC0356 intervention, splenic activation of natural killer (NK) cells and mRNA expression of cytokines and other immune molecules in the lungs were analysed. After 4 and 8 weeks, splenic NK cell activities were significantly higher in the TMC0356‐fed mice compared with control mice (P < 0.05). After 4 weeks, mRNA expression of interleukin‐2 and interferon‐(α and β) receptor 1 in lung cells is... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512987 Sat, 17 Dec 2011 14:37:35 +0100 5512987 http://www.medworm.com/index.php?rid=5512982&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02484.x AbstractExposure to microorganisms is considered an environmental factor which can contribute to Type 1 diabetes. Insulin binding proteins on microorganisms may induce production of antibodies which can react with the human insulin receptor (HIR) with possible consequences in developing a diabetic autoimmune response against HIR and insulin. The interaction of insulin with microorganisms was studied by screening forty‐five microbial species for their ability to bind insulin. Binding assays were performed using labelled insulin to identify insulin binding components on the microbes. Burkholderia multivorans and Burkholderia cenocepacia isolated from cystic fibrosis (CF) patients and the fish pathogen A.salmonicida were the only strains of those tested which showed insulin‐binding compon... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512982 Sat, 17 Dec 2011 14:36:25 +0100 5512982 http://www.medworm.com/index.php?rid=5569698&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02483.x AbstractFusarium oxysporum is a ubiquitous species complex of soil‐borne plant pathogens comprising of many different formae speciales, each characterized by a high degree of host specificity. In the present investigation, we surveyed microsatellites in the available express sequence tags and transcript sequences of three formae speciales of F. oxysporum viz. melonis (Fom), cucumerium (Foc), and lycopersici (Fol). The relative abundance and density of microsatellites were higher in Fom when compared with Foc and Fol. Thirty microsatellite primers were designed, ten from each forma specialis, for genetic characterization of F. oxysporum isolates belonging to five formae speciales. Of the 30 primers, only 14 showed amplification. A total of 28 alleles were amplified by 14 primers with an... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569698 Thu, 15 Dec 2011 05:00:00 +0100 5569698 http://www.medworm.com/index.php?rid=5512983&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02483.x AbstractFusarium oxysporum is a ubiquitous species complex of soil‐borne plant pathogens comprising of many different formae speciales, each characterized by a high degree of host specificity. In the present investigation, we surveyed microsatellites in the available Express Sequence Tags and transcript sequences of three formae speciales of F. oxysporum viz. melonis (Fom), cucumerium (Foc) and lycopersici (Fol). The relative abundance and density of microsatellites were higher in Fom when compared to Foc and Fol. Thirty microsatellite primers were designed, ten from each forma specialis, for genetic characterization of F. oxysporum isolates belonging to five formae speciales. Of the 30 primers, only 14 showed amplification. A total of 28 alleles were amplified by 14 primers with an aver... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512983 Thu, 15 Dec 2011 05:00:00 +0100 5512983 http://www.medworm.com/index.php?rid=5501731&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02481.x AbstractTonB‐dependent transporters (TBDTs) are bacterial outer membrane proteins that usually involve in uptake of certain key nutrients, for example, iron. In the genome of Salmonella enterica subsp. enterica serovar Typhi, yncD gene encodes a putative TBDT and was identified as an in vivo induced antigen recently. In the present study, a yncD‐deleted mutant was constructed to evaluate the role of the yncD gene in virulence. Our results showed that the mutant is attenuated to a mouse model by intraperitoneal injection, and its virulence is restored by the transformation of a complement plasmid. The competition experiments showed that the survival ability of the yncD‐deleted mutant in vivo decreases significantly. To evaluate its vaccine potential, the yncD‐deleted mutant was inoc... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5501731 Wed, 14 Dec 2011 16:03:27 +0100 5501731 http://www.medworm.com/index.php?rid=5594024&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02481.x AbstractTonB‐dependent transporters (TBDTs) are bacterial outer membrane proteins that are usually involved in the uptake of certain key nutrients, for example iron. In the genome of Salmonella enterica ssp. enterica serovar Typhi, the yncD gene encodes a putative TBDT and was identified recently as an in vivo‐induced antigen. In the present study, a yncD‐deleted mutant was constructed to evaluate the role of the yncD gene in virulence. Our results showed that the mutant is attenuated in a mouse model by intraperitoneal injection and its virulence is restored by the transformation of a complement plasmid. The competition experiments showed that the survival ability of the yncD‐deleted mutant decreases significantly in vivo. To evaluate its vaccine potential, the yncD‐deleted muta... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5594024 Mon, 12 Dec 2011 05:00:00 +0100 5594024 http://www.medworm.com/index.php?rid=5569695&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02480.x AbstractVarious combinations of antibiotics are reported to show synergy in treating nosocomial infections with multidrug‐resistant (MDR) Acinetobacter baumannii (A. baumannii). Here, we studied hospital‐acquired outbreak strains of MDR A. baumannii to evaluate optimal combinations of antibiotics. One hundred and twenty‐one strains were grouped into one major and one minor clonal group based on repetitive PCR amplification. Twenty representative strains were tested for antibiotic synergy using Etest®. Five strains were further analyzed by analytical isoelectric focusing and PCR to identify β‐lactamase genes or other antibiotic resistance determinants. Our investigation showed that the outbreak strains of MDR A. baumannii belonged to two dominant clones. A combination of colist... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569695 Mon, 12 Dec 2011 05:00:00 +0100 5569695 http://www.medworm.com/index.php?rid=5501733&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02480.x AbstractVarious combinations of antibiotics are reported to show synergy to treat nosocomial infections with multidrug resistant (MDR)‐Acinetobacter baumannii (A. baumannii). Here we studied hospital‐acquired outbreak strains of MDR‐A. baumannii to evaluate the optimal combinations of antibiotics. One hundred twenty‐one strains were grouped into one major and one minor clonal group based on repetitive‐polymerase chain reaction (rep‐PCR) amplification. Twenty representative strains were tested for antibiotic synergy using Etest®. Five strains were further analyzed by analytical isoelectric focusing and PCR to identify β‐lactamase resistance or other antibiotic resistance determinants. Our investigation showed that the outbreak strains of MDR‐A. baumannii belonged to two do... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5501733 Mon, 12 Dec 2011 05:00:00 +0100 5501733 http://www.medworm.com/index.php?rid=5501732&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02482.x AbstractIn Escherichia coli, cytosine DNA methylation is catalyzed by the Dcm (DNA cytosine methyltransferase) protein and occurs at the second cytosine in the sequence 5’CCWGG3’. Although the presence of cytosine DNA methylation was reported over 35 years ago, the biological role of 5‐methylcytosine in E. coli remains unclear. In order to gain insight into the role of cytosine DNA methylation in E. coli, we: (a) screened the 72 strains of the ECOR collection and 90 recently isolated environmental samples for the presence of the full‐length dcm gene using the polymerase chain reaction; (b) examined the same strains for the presence of 5‐methylcytosine at 5’CCWGG3’ sites using a restriction enzyme isoschizomer digestion assay; and (c) quantified the levels of 5‐methyl‐2’... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5501732 Mon, 12 Dec 2011 05:00:00 +0100 5501732 http://www.medworm.com/index.php?rid=5483923&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02479.x AbstractA real‐time PCR procedure targeting the gene of the molecular co‐chaperon DnaJ (dnaJ) was developed for specific detection of strains belonging to the Enterobacter cloacae group. The inclusivity and exclusivity of the real‐time PCR assay were assessed with seven reference strains of E. cloacae, 12 other Enterobacter species, and 41 non‐Enterobacter strains. Inclusivity as well as exclusivity of the duplex real‐time PCR was 100%. In contrast, resolution of MALDI‐TOF MS was inadequate for delineation of E. asburiae, E. hormaechei, E. kobei and E. ludwigii from E. cloacae. 11 of 56 (20%) clinical isolates of the E. cloacae group could not be clearly identified as a certain species using MALDI‐TOF MS. In summary, the combination of MALDI‐TOF MS with the E. cloacae speci... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5483923 Thu, 08 Dec 2011 15:20:24 +0100 5483923 http://www.medworm.com/index.php?rid=5569696&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02476.x In this study, we evaluated the in vitro antimicrobial efficacy of eight unsaturated fatty acids against Burkholderia cenocepacia K56‐2, a CF epidemic strain. Docosahexaenoic acid (DHA) was the most active compound. Its action can be either bacteriostatic or bactericidal, depending upon the concentration used. The effect of DHA was also evaluated on two others B. cenocepacia clinical isolates and compared with one representative member of all the 17 Bcc species. To test whether DHA could have a therapeutic potential, we assessed its efficacy using a Galleria mellonella caterpillar model of B. cenocepacia infection. We observed that the treatment of infected larvae with a single dose of DHA (50 mM) caused an increase in the survival rate as well as a reduced bacterial load. Moreover, DH... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5569696 Wed, 07 Dec 2011 05:00:00 +0100 5569696 http://www.medworm.com/index.php?rid=5483926&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02476.x In this study we evaluated the in vitro antimicrobial efficacy of eight unsaturated fatty acids against Burkholderia cenocepacia K56‐2, a CF epidemic strain. Docosahexaenoic acid (DHA) was the most active compound. Its action can be either bacteriostatic or bactericidal, depending upon the concentration used. The effect of DHA was also evaluated on two others B. cenocepacia clinical isolates and compared with one representative member of all the 17 Bcc species. To test whether DHA could have a therapeutic potential, we assessed its efficacy using a Galleria mellonella caterpillar model of B. cenocepacia infection. We observed that the treatment of infected larvae with a single dose of DHA (50 mM) caused an increase in the survival rate as well as a reduced bacterial load. Moreover, DHA a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5483926 Wed, 07 Dec 2011 05:00:00 +0100 5483926 http://www.medworm.com/index.php?rid=5483925&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02477.x AbstractSulfoquinovose (SQ, 6‐deoxy‐6‐sulfoglucose) was synthesized chemically. An HPLC‐ELSD method to separate SQ and other chromophore‐free sulfonates e.g. 2,3‐dihydroxypropane‐1‐sulfonate (DHPS) was developed. A set of 10 genome‐sequenced, sulfonate‐utilizing bacteria did not utilize SQ, but an isolate, Pseudomonas putida SQ1, from an enrichment culture did so. The molar growth yield with SQ was half of that with glucose, and 1 mol 3‐sulfolactate (mol SQ)−1 was formed during growth. The 3‐sulfolactate was degraded by addition of Paracoccus pantotrophus NKNCYSA, and the sulfonate‐sulfur was recovered quantitatively as sulfate. Another isolate, Klebsiella oxytoca TauN1, could utilize SQ, forming 1 mol DHPS (mol SQ)−1; the molar growth yield with SQ was half... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5483925 Wed, 07 Dec 2011 05:00:00 +0100 5483925 http://www.medworm.com/index.php?rid=5483924&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02478.x AbstractFtsY is the receptor of the signal recognition particle that mediates the targeting of integral membrane proteins in bacteria. It was shown that in Escherichia coli, the N‐terminal region of FtsY contributes to its interaction with the membrane, but it is not inserted into the membrane. However, this study presents evidence that in Streptomyces coelicolor, FtsY has a hydrophobic region at its N‐terminus, which forms a membrane insertion structure and contributes significantly to the binding between FtsY and membrane. Through membrane protein extraction followed by immunoblotting, we demonstrated that deletion of the N‐terminal residues 11‐39 from the S. coelicolor FtsY (ScFtsY) drastically reduced its membrane binding capability, and that the N‐terminus of ScFtsY alone wa... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5483924 Wed, 07 Dec 2011 05:00:00 +0100 5483924 http://www.medworm.com/index.php?rid=5473958&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02475.x AbstractCerato‐platanin (CP) is a protein produced by Ceratocystis platani, the causal agent of canker stain disease of plane trees. CP is the first member of the “cerato‐platanin family” and its role as a PAMP (pathogen‐associated molecular pattern), inducing defence responses both in host and non‐host plants, is established. However, the primary role of CP and its homologues in the fungal life remains unknown. In the present work we investigated the regulation of the cp gene during the in vitro growth of C. platani in different conditions and under the effect of potential stress factors. Fungal growth and conidiogenesis were also analyzed. Results showed that cp is a single‐copy gene whose expression level is strictly associated to hyphal growth and to chlamydospores format... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5473958 Mon, 05 Dec 2011 15:21:21 +0100 5473958 http://www.medworm.com/index.php?rid=5512984&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02473.x AbstractThe presence of chromate‐resistance genes in enterobacteria was evaluated in a collection of 109 antibiotic‐resistant nosocomial isolates from nine major cities in México. Results were compared with the presence of mercury‐resistance genes. Susceptibility tests showed that 21% of the isolates were resistant to chromate (CrR), whereas 36% were resistant to mercury (HgR). CrR levels were high in Klebsiella pneumoniae (61%), low in Enterobacter cloacae (12%) and Escherichia coli (4%), and null in Salmonella sp. isolates. Colony hybridization demonstrated that the majority of metal‐resistant isolates hybridized with chrA gene (87% of CrR isolates), encoding a CHR transporter homologue, and merA gene (74% of HgR isolates), encoding MerA mercuric reductase, suggesting that most ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512984 Fri, 02 Dec 2011 05:00:00 +0100 5512984 http://www.medworm.com/index.php?rid=5465767&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02473.x AbstractThe presence of chromate‐resistance genes in enterobacteria was evaluated in a collection of 109 antibiotic‐resistant nosocomial isolates from nine major cities in México. Results were compared with presence of mercury‐resistance genes. Susceptibility tests showed that 21% of the isolates were resistant to Chromate (CrR), whereas 36% were resistant to Mercury (HgR). CrR levels were high in Klebsiella pneumoniae (61%), low in Enterobacter cloacae (12%) and Escherichia coli (4%), and null in Salmonella sp. isolates. Colony hybridization demonstrated that the majority of metal‐resistant isolates hybridized with chrA gene (87% of CrR isolates), encoding a CHR transporter homologue, and merA gene (74% of HgR isolates), encoding MerA mercuric reductase, suggesting that most isol... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465767 Fri, 02 Dec 2011 05:00:00 +0100 5465767 http://www.medworm.com/index.php?rid=5465769&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02471.x A novel aerobic, gram‐negative bacterial strain, designated KU41ET, which degrades p‐n‐nonylphenol, was isolated from seawater obtained from the coastal region of Ishigaki Island, Japan. Cells are motile, curved rods with a single polar flagellum. Strain KU41ET grew at 20–35°C, pH 7.0–8.0, in the presence of 1.0–4.0% NaCl. The predominant respiratory lipoquinone was ubiquinone‐8, and the major cellular fatty acids were summed feature 3 (C15:0 iso 2OH and/or C16:1 ω7c, 28.4%), C18:1 ω7c (19.8%), and C16:0 (17.0%). The DNA G+C content was 48.6 mol%. The 16S rRNA gene sequence analysis indicated that strain KU41ET is affiliated with the order Alteromonadales within the class Gammaproteobacteria and is most closely related to Pseudoteredinibacter isoporae SW‐11T (93.6% simil... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465769 Thu, 01 Dec 2011 05:00:00 +0100 5465769 http://www.medworm.com/index.php?rid=5465768&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02472.x AbstractListeria monocytogenes is a Gram positive pathogen that is ubiquitous in the environment. It is a facultative anaerobic rod which causes listeriosis, a disease with potentially lethal consequences for susceptible individuals. During infection the pathogen is capable of sequestering metal ions to act as vital biocatalysts in cellular processes. The zinc uptake regulator (ZurR) is predicted to coordinate uptake of zinc from the external environment. An in‐frame deletion of the zurR gene resulted in a mutant exhibiting a small colony phenotype and a smaller cell size. The zurR mutant was unaffected under conditions of zinc limitation but demonstrated increased sensitivity to toxic levels of zinc. The mutant also demonstrated a significant (1‐log) reduction in virulence potential i... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465768 Thu, 01 Dec 2011 05:00:00 +0100 5465768 http://www.medworm.com/index.php?rid=5465766&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02474.x AbstractRedP is proposed to initiate undecylprodiginine biosynthesis in Streptomyces coelicolor by condensing an acyl‐CoA with malonyl‐ACP, and is homologous to FabH which catalyzes the same reaction for initiation of fatty acid biosynthesis. Herein, we report the substrate specificities of RedP and FabH from assays using pairings of two acyl‐CoA substrates (acetyl‐CoA and isobutyryl‐CoA) and two malonyl‐ACP substrates (malonyl‐RedQ and malonyl‐FabC). RedP activity was observed only with a pairing of acetyl‐CoA and malonyl‐RedQ, consistent with its proposed role in initiating formation of acetyl CoA‐derived prodiginines. Malonyl‐FabC is not a substrate for RedP, indicating that ACP specificity is one of the factors that permit a separation between prodiginine and fa... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465766 Thu, 01 Dec 2011 05:00:00 +0100 5465766 http://www.medworm.com/index.php?rid=5454449&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02469.x This study also demonstrates that atypical Shigella B13 strains are more closely related to attaching and effacing E. coli and that their evolution recapitulates the progression from ancestral E. coli to EHEC. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5454449 Tue, 29 Nov 2011 14:57:49 +0100 5454449 http://www.medworm.com/index.php?rid=5534251&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02468.x AbstractMcsA is a key modulator of stress response in Staphylococcus aureus that contains four CXXC potential metal‐binding motifs at the N‐terminal. Staphylococcus aureus ctsR operon encodes ctsR, clpC, and putative mcsA and mcsB genes. The expression of the ctsR operon in S. aureus was shown to be induced in response to various types of heavy metals such as copper and cadmium. McsA was cloned and overexpressed, and purified product was tested for metal‐binding activity. The protein bound to Cu(II),Zn(II),Co(II), and Cd(II). No binding with any heavy metal except copper was found when we performed site‐directed mutagenesis of Cys residues of three CXXC motifs of McsA. These data suggest that two conserved cysteine ligands provided by one CXXC motif are required to bind copper ion... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5534251 Tue, 29 Nov 2011 05:00:00 +0100 5534251 http://www.medworm.com/index.php?rid=5454451&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02468.x AbstractMcsA is a key modulator of stress response in Staphylococcus aureus that contains four CXXC potential metal binding motifs at the N‐terminal. S. aureus ctsR operon encodes ctsR, clpC and putative mcsA and mcsB genes. The expression of the ctsR operon in S. aureus was shown to be induced in response to various types of heavy metals such as copper and cadmium. McsA was cloned and overexpressed, and purified product was tested for metal binding activity. The protein bound to Cu(II), Zn(II), Co(II) and Cd(II). No binding with any heavy metal except copper was found when we performed site directed mutagenesis of Cys residues of three CXXC motifs of McsA. These data suggest that two conserved cysteine ligands provided by one CXXC motif are required to bind copper ions. In addition, usi... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5454451 Tue, 29 Nov 2011 05:00:00 +0100 5454451 http://www.medworm.com/index.php?rid=5454450&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02470.x This study can extend our understanding of the biological function of probiotic genomic DNA as an anti‐inflammatory agent. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5454450 Tue, 29 Nov 2011 05:00:00 +0100 5454450 http://www.medworm.com/index.php?rid=5447952&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02467.x AbstractAn isocitrate dehydrogenase from Zymomonas mobilis was overexpressed in Escherichia coli as a fused protein (ZmIDH). The molecular mass of recombinant ZmIDH, together with its 6×His partner, was estimated to be 74 kDa by gel filtration chromatography, suggesting a homodimeric structure. The purified recombinant ZmIDH displayed maximal activity at 55 °C, pH 8.0 with Mn2+ and pH 8.5 with Mg2+. Heat inactivation studies showed that the recombinant ZmIDH was rapidly inactivated above 40 °C. In addition, the recombinant ZmIDH activity was completely dependent on the divalent cation and Mn2+ was the most effective cation. The recombinant ZmIDH displayed a 165‐fold (kcat/Km) preference for NAD+ over NADP+ with Mg2+, and a 142‐fold greater specificity for NAD+ than NADP+ with Mn2+. ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5447952 Sat, 26 Nov 2011 15:36:50 +0100 5447952 http://www.medworm.com/index.php?rid=5501734&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02467.x AbstractAn isocitrate dehydrogenase from Zymomonas mobilis was overexpressed in Escherichia coli as a fused protein (ZmIDH). The molecular mass of recombinant ZmIDH, together with its 6× His partner, was estimated to be 74 kDa by gel filtration chromatography, suggesting a homodimeric structure. The purified recombinant ZmIDH displayed maximal activity at 55 °C, pH 8.0 with Mn2+ and pH 8.5 with Mg2+. Heat inactivation studies showed that the recombinant ZmIDH was rapidly inactivated above 40 °C. In addition, the recombinant ZmIDH activity was completely dependent on the divalent cation and Mn2+ was the most effective cation. The recombinant ZmIDH displayed a 165‐fold (kcat/Km) preference for NAD+ over NADP+ with Mg2+, and a 142‐fold greater specificity for NAD+ than NADP+ with Mn2... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5501734 Fri, 25 Nov 2011 05:00:00 +0100 5501734 http://www.medworm.com/index.php?rid=5437709&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02465.x AbstractHorizontal gene transfer (HGT) is frequently observed in prokaryotes and until recently was assumed to be of limited importance to eukaryotes. However there is an increasing body of evidence to suggest that HGT is an important mechanism in eukaryotic genome evolution, particularly in unicellular organisms. The transfer of individual genes, gene clusters or entire chromosomes can have significant impacts on niche specification, disease emergence or shift in metabolic capabilities. In terms of genomic sequencing, the fungal kingdom is one of the most densely sampled eukaryotic lineages and is at the forefront of eukaryote comparative genomics and enables us to use fungi to study eukaryotic evolutionary mechanisms including HGT. This review describes the bioinformatics based methodolo... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437709 Wed, 23 Nov 2011 14:23:18 +0100 5437709 http://www.medworm.com/index.php?rid=5437710&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02466.x AbstractNopT1 and NopT2, putative type III effectors from the plant symbiotic bacterium Bradyrhizobium japonicum, are predicted to belong to a family of YopT/AvrPphB effectors, which are cysteine proteases. In the present study, we showed that both NopT1 and NopT2 indeed possess cysteine protease activity. When overexpressed in Escherichia coli, both NopT1 and NopT2 undergo autoproteolytic processing which is largely abolished in the presence of E‐64, a papain family‐specific inhibitor. Mutations of NopT1 disrupting either the catalytic triad or the putative autoproteolytic site reduce or markedly abolish the protease activity. Autocleavage likely occurs between residues K48 and M49, though another potential cleavage site is also possible. NopT1 also elicitis HR‐like cell death when ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437710 Wed, 23 Nov 2011 05:00:00 +0100 5437710 http://www.medworm.com/index.php?rid=5534250&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02463.x AbstractThe function of whcB, one of the four whiB homologues of Corynebacterium glutamicum, was assessed. Cells carrying the P180‐whcB clone, and thus overexpressing the whcB gene, showed retarded growth, probably due to increased sensitivity to oxidants, whereas cells lacking whcB (ΔwhcB) did not. However, growth retardation was not observed in cells with additionally whcE deleted. Furthermore, the ΔwhcE phenotype, characterized by slow growth and sensitivity to oxidants, was reversed in cells carrying P180‐whcB. Like the whcE gene, which is also known as a whiB homologue, the whcB gene was preferentially expressed in stationary phase. Determination of the genes under regulation of whcB using two‐dimensional polyacrylamide gel electrophoresis identified several genes involved in ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5534250 Mon, 21 Nov 2011 05:00:00 +0100 5534250 http://www.medworm.com/index.php?rid=5512986&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02461.x AbstractThe mycotoxin deoxynivalenol (DON), a secondary metabolite produced by species of the plant pathogen Fusarium, causes serious problems in cereal crop production because of its toxicity towards humans and livestock. A biological approach for the degradation of DON using a DON‐degrading bacterium (DDB) appears to be promising, although information about DDBs is limited. We isolated 13 aerobic DDBs from a variety of environmental samples, including field soils and wheat leaves. Of these 13 strains, nine belonged to the Gram‐positive genus Nocardioides and other four to the Gram‐negative genus Devosia. The degradation phenotypes of the two Gram types were clearly different; all washed cells of the 13 strains degraded 100 μg mL−1DON to below the detection limit (0.5 μg mL�... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512986 Mon, 21 Nov 2011 05:00:00 +0100 5512986 http://www.medworm.com/index.php?rid=5493024&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02462.x AbstractA cryptic plasmid from Arthrobacter rhombi PRH1, designated as pPRH, was sequenced and characterized. It was 5000 bp in length with a G+C content of 66 mol%. The plasmid pPRH was predicted to encode six putative open reading frames (ORFs), in which ORF2 and ORF3 formed the minimal replicon of plasmid pPRH and shared 55–61% and 60–69% homology, respectively, with the RepA and RepB proteins of reported rhodococcal plasmids. Sequence analysis revealed a typical ColE2‐type ori located 45 bp upstream of the gene repA. Sequence and phylogenetic analysis led to the conclusion that pPRH is a representative of a novel group of pAL5000 subfamily of ColE2 family plasmids. Three shuttle vectors pRMU824, pRMU824Km and pRMU824Tc, encoding chloramphenicol resistance, were constructed. Th... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5493024 Mon, 21 Nov 2011 05:00:00 +0100 5493024 http://www.medworm.com/index.php?rid=5437715&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02460.x AbstractHerbicides have the potential to impair the metabolism of soil microorganisms. The current study addressed the toxic effect of Bentazon and 4‐chloro‐2‐methylphenoxyacetic acid (MCPA) on aerobic and anaerobic Bacteria that are involved in cellulose and cellobiose degradation in an agricultural soil. Aerobic saccharide degradation was reduced at concentrations of herbicides above environmental values. Microbial processes (e.g. fermentations, ferric iron reduction) that were linked to anaerobic cellulose and cellobiose degradation were reduced in the presence of both herbicides at concentrations above and at those that occur in crop field soil. 16S rRNA gene transcript numbers of total Bacteria, and selected bacterial taxa (Clostridia [Group I], Planctomycetaceae, and two uncult... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437715 Mon, 21 Nov 2011 05:00:00 +0100 5437715 http://www.medworm.com/index.php?rid=5437714&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02461.x AbstractThe mycotoxin deoxynivalenol (DON), a secondary metabolite produced by the plant pathogen Fusarium species, causes serious problems in cereal crop production because of its toxicity towards humans and livestock. A biological approach for the degradation of DON using a DON‐degrading bacterium (DDB) is promising, although information about DDB is limited. We isolated 13 aerobic DDBs from a variety of environmental samples, including field soils and wheat leaves. Of these 13 strains, nine belonged to the Gram‐positive genus Nocardioides, and other four the Gram‐negative genus Devosia. The degradation phenotypes of the two Gram types were clearly different; all washed cells of the 13 strains degraded 100 μg mL−1 of DON to below the detection limit (0.5 μg mLl−1), but the in... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437714 Mon, 21 Nov 2011 05:00:00 +0100 5437714 http://www.medworm.com/index.php?rid=5437713&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02464.x AbstractSecretins are channels that allow translocation of macromolecules across the outer membranes of Gram‐negative bacteria. Virulence, natural competence and motility are among the functions mediated by these large oligomeric protein assemblies. Filamentous phage also uses secretins to exit their bacterial host without causing cell lysis. However, the secretin is only a part of a larger membrane‐spanning complex and additional proteins are often required for its formation. A class of outer membrane lipoproteins called pilotins has been implicated in secretin assembly and/or localization. Additional accessory proteins may also be involved in secretin stability. Significant progress has recently been made towards deciphering the complex interactions required for functional secretin a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437713 Mon, 21 Nov 2011 05:00:00 +0100 5437713 http://www.medworm.com/index.php?rid=5437712&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02462.x AbstractA cryptic plasmid from Arthrobacter rhombi PRH1, designated as pPRH, was sequenced and characterized. It was 5000 bp in length with a G+C content of 66 mol%. The plasmid pPRH was predicted to encode six putative ORFs, in which ORF2 and ORF3 formed the minimal replicon of plasmid pPRH and shared 55–61% and 60–69% homology, respectively, with the RepA and RepB proteins of reported rhodococcal plasmids. Sequence analysis revealed a typical ColE2‐type ori located 45 bp upstream of the gene repA. Sequence and phylogenetic analysis led to the conclusion that pPRH is a representative of a novel group of the pAL5000 subfamily of ColE2 family plasmids. Three shuttle vectors pRMU824, pRMU824Km and pRMU824Tc, encoding chloramphenicol resistance, were constructed. The latter two harboure... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437712 Mon, 21 Nov 2011 05:00:00 +0100 5437712 http://www.medworm.com/index.php?rid=5437711&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02463.x AbstractThe function of whcB, one of the four whiB homologues of Corynebacterium glutamicum, was assessed. Cells carrying the P180‐whcB clone, and thus overexpressing the whcB gene, showed retarded growth probably due to increased sensitivity to oxidants, whereas cells with deleted whcB (ΔwhcB) did not. However, growth retardation was not observed in cells with additionally whcE deleted. Furthermore, the ΔwhcE phenotype, characterized by slow growth and sensitivity to oxidants, was cured in cells carrying P180‐whcB. Like the whcE gene, which is also known as a whiB homologue, the whcB gene was preferentially expressed in stationary phase. Determination of the genes under regulation of whcB using 2D‐PAGE analysis identified several genes involved in electron transfer reactions that ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437711 Mon, 21 Nov 2011 05:00:00 +0100 5437711 http://www.medworm.com/index.php?rid=5418534&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02458.x AbstractNew fast‐growing and less bitter varieties of Hypsizygus marmoreus were developed by crossing monokaryotic mycelia from a commercial strain (Hm1‐1) and a wild strain (Hm3‐10). Six of better tasting new strains with shorter cultivation period were selected from 400 crosses in the large scale cultivation experiment. We next attempted to develop sequence characterized amplified region (SCAR) markers to identify the new strain from other commercial strains. For the SCAR markers, we conducted molecular genetic analysis on a wild strain and the 8 most cultivated H. marmoreus strains collected from various areas in East Asia by randomly amplified polymorphic DNA (RAPD). Ten unique DNA bands for a commercial Hm1‐1 strain and the Hm3‐10 strain were extracted and their sequences we... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5418534 Fri, 18 Nov 2011 05:01:28 +0100 5418534 http://www.medworm.com/index.php?rid=5512985&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02455.x AbstractExtensive denitrification resulted in a dramatic increase in pH (from 6.8 to 9.5) in nitrate‐impacted, acetate‐amended sediment microcosms containing sediment representative of the Sellafield nuclear facility, UK. Denitrification was followed by Fe(III) reduction, indicating the presence of alkali‐tolerant, metal‐reducing bacteria. A close relative (99% 16S rRNA gene sequence homology) to Serratia liquefaciens dominated progressive enrichment cultures containing Fe(III)‐citrate as the sole electron acceptor at pH 9 and was isolated aerobically using solid media. The optimum growth conditions for this facultatively anaerobic Serratia species were investigated, and it was capable of metabolizing a wide range of electron acceptors including oxygen, nitrate, FeGel,Fe‐NTA an... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5512985 Thu, 17 Nov 2011 05:00:00 +0100 5512985 http://www.medworm.com/index.php?rid=5418538&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02459.x AbstractGene duplication and horizontal gene transfer are two events that enable the generation of new genes. Rhodobacter sphaeroides (WS8 and 2.4.1 strains) has four copies of the rpoN gene that are not functionally interchangeable. Until now this is the only example of specialization of this sigma factor. In this work, we aimed to determine if the multiple copies of this gene originated from horizontal gene transfer or through gene duplication. Our results suggest a multiplication origin of the different rpoN copies that occurred after the Rhodobacter clade separated. Functional tests indicate that the specialization of the rpoN genes is not restricted to R. sphaeroides. We propose that the rpoN copy involved in nitrogen fixation is the ancestral gene and that the other rpoN genes have ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5418538 Thu, 17 Nov 2011 05:00:00 +0100 5418538 http://www.medworm.com/index.php?rid=5418537&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02455.x AbstractExtensive denitrification resulted in a dramatic increase in pH (from 6.8 – 9.5) in nitrate‐impacted, acetate‐amended sediment microcosms containing sediment representative of the Sellafield nuclear facility, UK. Denitrification was followed by Fe(III) reduction, indicating the presence of alkali‐tolerant metal‐reducing bacteria. A close relative (99% 16S rRNA gene sequence homology) to Serratia liquefaciens dominated progressive enrichment cultures containing Fe(III)‐citrate as the sole electron acceptor at pH 9, and was isolated aerobically using solid media. The optimum growth conditions for this facultatively anaerobic Serratia species were investigated and it was capable of metabolising a wide range of electron acceptors including oxygen, nitrate, FeGel, Fe‐NTA a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5418537 Thu, 17 Nov 2011 05:00:00 +0100 5418537 http://www.medworm.com/index.php?rid=5418536&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02456.x AbstractBacillus subtilis possesses Crh, which is a paralog of the histidine protein HPr of the phosphotransferase system (PTS). Like HPr, Crh becomes (de)phosphorylated in vitro at residue Ser46 by the metabolite‐controlled HPr kinase/phosphorylase HPrK/P. Depending on its phosphorylation state, Crh exerts regulatory functions in connection with carbohydrate metabolism. So far, knowledge on phosphorylation of Crh in vivo has been limited and derived from indirect evidence. Here, we studied the dynamics of Crh phosphorylation directly by non‐denaturing gel electrophoresis followed by Western analysis. The results confirm that HPrK/P is the single kinase catalyzing phosphorylation of Crh in vivo. Accordingly, phosphorylation of Crh is triggered by the carbon source as observed previousl... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5418536 Thu, 17 Nov 2011 05:00:00 +0100 5418536 http://www.medworm.com/index.php?rid=5418535&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02457.x AbstractInhibition by light potentially influences the distribution of ammonia oxidisers in aquatic environments and is one explanation for nitrite maxima near the base of the euphotic zone of oceanic waters. Previous studies of photoinhibition have been restricted to bacterial ammonia oxidisers, rather than archaeal ammonia oxidisers, which dominate in marine environments. To compare photoinhibition of bacterial and archaeal ammonia oxidisers, specific growth rates of two ammonia oxidizing archaea (Nitrosopumilus maritimus and Nitrosotalea devanaterra) and bacteria (Nitrosomonas europaea and Nitrosospira multiformis) were determined at different light intensities under continuous illumination and light:dark cycles. All strains were inhibited by continuous illumination at the highest inten... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5418535 Thu, 17 Nov 2011 05:00:00 +0100 5418535 http://www.medworm.com/index.php?rid=5397515&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02410.x AbstractPolyethylene glycol (PEG)‐induced cell fusion is a promising method to transfer larger DNA from one cell to another than conventional genetic DNA transfer systems. The laboratory strain Bacillus subtilis 168 contains a restriction (R) and modification (M) system, BsuM, which recognizes the sequence 5′‐CTCGAG‐3′. To study whether the BsuM system affects DNA transfer by the PEG‐induced cell fusion between R+M+ and R−M− strains, we examined transfer of plasmids pHV33 and pLS32neo carrying no and eight BsuM sites, respectively. It was shown that although the transfer of pLS32neo but not pHV33 from the R−M− to R+M+ cells was severely restricted, significant levels of transfer of both plasmids from the R+M+ to R−M− cells were observed. The latter result shows that... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397515 Fri, 11 Nov 2011 15:38:45 +0100 5397515 http://www.medworm.com/index.php?rid=5397510&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02453.x This study investigates new aspects of the possible role of antioxidant defenses in the mechanisms of resistance to ciprofloxacin in Proteus mirabilis. Four Ciprofloxacin Resistant Variants (CRVs), selected in vitro by repeated cultures in a sub‐MIC concentration of ciprofloxacin, attained different levels of antibiotic resistance and high Ferric Reducing Antioxidant Power, with 10‐6 frequencies. However, no mutations occurred in positions 83 or 87 of gyrA; 464 or 466 of gyrB; or 78, 80 or 84 of parC, suggesting that resistance taken place without these typical mutations in DNA gyrase or topoisomerase IV. Assays with ciprofloxacin, and the pump inhibitor carbonyl cyanide m‐chlorophenylhydrazone showed that in addition to the antioxidant mechanisms, the influx/efflux mechanism also co... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397510 Fri, 11 Nov 2011 15:37:35 +0100 5397510 http://www.medworm.com/index.php?rid=5465770&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02452.x AbstractStenotrophomonas species are found commonly in environmental and clinical samples; Stenotrophomonas maltophilia is an important opportunistic pathogen of humans. Traditional phenotyping protocols, as well as genotyping by 16S rRNA gene sequence analysis, do not reliably distinguish the species of Stenotrophomonas. Sequence analyses of two targeted PCR‐amplified regions of the gyrB gene, which encodes the β‐subunit of DNA gyrase, enabled resolution and identification of these species. Most type strains of the different species of Stenotrophomonas exhibited more than 7% dissimilarity in the gyrB gene sequences. Among these, strains identified as the same species exhibited sequence dissimilarities up to 4.6% and 5.9% for the two regions, respectively. Strains identified as S. ma... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465770 Tue, 08 Nov 2011 05:00:00 +0100 5465770 http://www.medworm.com/index.php?rid=5447954&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02453.x This study investigates new aspects of the possible role of antioxidant defenses in the mechanisms of resistance to ciprofloxacin in Proteus mirabilis. Four ciprofloxacin‐resistant variants (CRVs), selected in vitro by repeated cultures in a sub‐minimum inhibitory concentration (MIC) concentration of ciprofloxacin, attained different levels of antibiotic resistance and high Ferric reducing antioxidant power, with 10−6 frequencies. However, no mutations occurred in positions 83 or 87 of gyrA, 464 or 466 of gyrB, or 78, 80 or 84 of parC, suggesting that resistance took place without these typical mutations in DNA gyrase or topoisomerase IV. Assays with ciprofloxacin and the pump inhibitor carbonyl cyanide m‐chlorophenylhydrazone showed that in addition to the antioxidant mechanisms, ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5447954 Tue, 08 Nov 2011 05:00:00 +0100 5447954 http://www.medworm.com/index.php?rid=5447953&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02451.x AbstractThe presence of toxigenic cyanobacteria capable of biosynthesis of cylindrospermopsin (CYN) was measured in 24 water samples collected from the lakes Bytyńskie (BY) and Bnińskie (BN) in the Western Poland. The study also covered analysis of toxigenicity and production of CYN by the culture of Cylindrospermopsis raciborskii isolated from BY. The cyrJ gene associated with CYN production was identified in 22 water samples collected in the summer seasons of 2006 and 2007. The presence of CYN was confirmed in 16 samples. The homology searches revealed that amplified sequences of four water samples, which were selected from among all the samples, displayed a strong 99% homology to cyrJ gene of Aphanizomenon sp. 10E6. The culture of C. raciborskii did not contain the cyrJ gene nor the ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5447953 Tue, 08 Nov 2011 05:00:00 +0100 5447953 http://www.medworm.com/index.php?rid=5397513&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02454.x In this study, the inducible catalase promoter (PcatR) from A. niger was characterized. For this, constructs were developed and checked for the expression of the alkaline xylanase gene transcriptionally fused under the cat R promoter. Two versions of the catalase (catR) promoter sequence from A. niger (Pcat300, Pcat924) were isolated and tested for their ability to drive expression of the alkaline xylanase (alx) gene. Pcat924 showed better efficiency (more than ten fold increase in AlX activity compared to Pcat300) under the optimized culture conditions. Induction of the catR promoter with 0.20% H2O2 and 1.5% CaCO3 in the culture medium, further increased expression of AlX to 2.61 and 2.20 fold respectively clarifying its inducible nature. Specific induction or repression of the catR promo... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397513 Tue, 08 Nov 2011 05:00:00 +0100 5397513 http://www.medworm.com/index.php?rid=5397512&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02451.x AbstractThe presence of toxigenic cyanobacteria capable of biosynthesis of cylindrospermopsin (CYN) was measured in 24 water samples collected from the lakes Bytyńskie (BY) and Bnińskie (BN) in the Western Poland. The study also covered analysis of toxigenicity and production of CYN by the culture of C. raciborskii isolated from BY. The cyrJ gene associated with CYN production was identified in 22 water samples collected in the summer seasons of 2006 and 2007. The presence of CYN was confirmed in 16 samples. The homology searches revealed that amplified sequences of 4 water samples, which were selected from among all the samples, displayed a strong 99% homology to cyrJ gene of Aphanizomenon sp. 10E6. The culture of C. raciborskii did not contain the cyrJ gene nor the CYN. The specificity... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397512 Tue, 08 Nov 2011 05:00:00 +0100 5397512 http://www.medworm.com/index.php?rid=5397511&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02452.x AbstractStenotrophomonas species are found commonly in environmental and clinical samples; S. maltophilia is an important opportunistic pathogen of humans. Traditional phenotyping protocols, as well as genotyping by 16S rRNA gene sequence analysis, do not reliably distinguish the species of Stenotrophomonas. Sequence analyses of two targeted PCR‐amplified regions of the gyrB gene, which encodes the β‐subunit of DNA gyrase, enabled resolution and identification of these species. Most type strains of the different species of Stenotrophomonas exhibited more than 7% dissimilarity in the gyrB gene sequences. Among these, strains identified as the same species exhibited sequence dissimilarities up to 4.6% and 5.9% for the two regions, respectively. Strains identified as S. maltophilia, with... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397511 Tue, 08 Nov 2011 05:00:00 +0100 5397511 http://www.medworm.com/index.php?rid=5493023&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02450.x AbstractShewanella oneidensis MR‐1 has conventionally been considered unable to use glucose as a carbon substrate for growth. The genome sequence of S. oneidensis MR‐1 however suggests the ability to use glucose. Here, we demonstrate that during initial glucose exposure, S. oneidensis MR‐1 quickly and frequently gains the ability to utilize glucose as a sole carbon source, in contrast to wild‐type S. oneidensis, which cannot immediately use glucose as a sole carbon substrate. High‐performance liquid chromatography and 14C glucose tracer studies confirm the disappearance in cultures and assimilation and respiration, respectively, of glucose. The relatively short time frame with which S. oneidensis MR‐1 gained the ability to use glucose raises interesting ecological implicati... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5493023 Sat, 05 Nov 2011 04:00:00 +0100 5493023 http://www.medworm.com/index.php?rid=5397514&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02450.x AbstractShewanella oneidensisMR‐1 has conventionally been considered unable to use glucose as a carbon substrate for growth. The genome sequence of S. oneidensisMR‐1 however, suggests the ability to use glucose. Here we demonstrate that during initial glucose exposure, S. oneidensisMR‐1 quickly and frequently gains the ability to utilize glucose as a sole carbon source, in contrast to wild‐type S. oneidensis which cannot immediately use glucose as a sole carbon substrate. HPLC and 14C‐glucose tracer studies confirm the disappearance in cultures and assimilation and respiration, respectively, of glucose. The relatively short time frame with which S. oneidensisMR‐1 gained the ability to use glucose raises interesting ecological implications. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5397514 Sat, 05 Nov 2011 04:00:00 +0100 5397514 http://www.medworm.com/index.php?rid=5437716&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02447.x (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5437716 Thu, 03 Nov 2011 04:00:00 +0100 5437716 http://www.medworm.com/index.php?rid=5428636&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02448.x AbstractProteins of the YgfZ family occur in all domains of life and are characterized by the conserved dodecapeptide motif KGC[Y/F]‐x‐GQE‐x3‐[R/K]. YgfZ proteins are known to participate in assembly or repair of iron/sulphur clusters, and to require folate for biological activity, but their mechanism of action is unknown. To assess the importance of individual residues in the conserved motif, Escherichia coli Ygf Z was expressed from a plasmid in a ΔygfZ strain and subjected to alanine‐scanning mutagenesis. The impacts on YgfZ functionality were evaluated by assays of growth and of the in vivo activity of the iron/sulphur enzyme MiaB, which modifies tRNA. By these criteria, the motif's tyrosine residue (Y229) had a detectable influence but only the cysteine residue (C228) was ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5428636 Thu, 03 Nov 2011 04:00:00 +0100 5428636 http://www.medworm.com/index.php?rid=5376525&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02447.x (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376525 Thu, 03 Nov 2011 04:00:00 +0100 5376525 http://www.medworm.com/index.php?rid=5376524&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02448.x AbstractProteins of the YgfZ family occur in all domains of life and are characterized by the conserved dodecapeptide motif KGC[Y/F]‐x‐GQE‐x3‐[R/K]. YgfZ proteins are known to participate in assembly or repair of iron/sulfur clusters, and to require folate for biological activity, but their mechanism of action is unknown. To assess the importance of individual residues in the conserved motif, Escherichia coli YgfZ was expressed from a plasmid in a ΔygfZ strain and subjected to alanine‐scanning mutagenesis. The impacts on YgfZ functionality were evaluated by assays of growth and of the in vivo activity of the iron/sulfur enzyme MiaB, which modifies tRNA. By these criteria, the motif's tyrosine residue (Y229) had a detectable influence but only the cysteine residue (C228) was crit... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376524 Thu, 03 Nov 2011 04:00:00 +0100 5376524 http://www.medworm.com/index.php?rid=5376523&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02449.x AbstractReactive oxygen species (ROS) are a key feature of plant (and animal) defences against invading pathogens. As a result, plant pathogens must be able to either prevent their production, or to tolerate high concentrations of these highly reactive chemicals. In this review we focus on plant pathogenic bacteria of the genus Pseudomonas and the ways in which they overcome the challenges posed by ROS. We also explore the ways in which pseudomonads may exploit plant ROS generation for their own purposes, and even produce ROS directly as part of their infection mechanisms. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376523 Tue, 01 Nov 2011 04:00:00 +0100 5376523 http://www.medworm.com/index.php?rid=5465771&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02446.x AbstractThe Mycobacterium tuberculosis murG gene, Rv2153, was expressed in Escherichia coli murG(Ts) strain OV58 on a plasmid under the control of the arabinose‐inducible araBAD promoter. Mycobacterium tuberculosis murG rescued the growth of E. coli murG(Ts) at the nonpermissive temperature: transformants were only obtained in the presence of 0.2% arabinose at 42 °C, and their growth rate was dependent on arabinose concentrations. However, no MurG activity was detected in membranes from the transformant grown in arabinose at 42 °C, while MraY activity was normal. This observation led to the development of a membrane‐based scintillation proximity assay for exogenous sources of MurG. Addition of purified E. coli MurG resulted in the reconstitution of MurG and peptidoglycan synthesi... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5465771 Mon, 31 Oct 2011 04:00:00 +0100 5465771 http://www.medworm.com/index.php?rid=5376527&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02446.x AbstractThe Mycobacterium tuberculosis murG gene, Rv2153, was expressed in Escherichia coli murG(Ts) strain OV58 on a plasmid under the control of the arabinose‐inducible araBAD promoter. M. tuberculosis murG rescued growth of E. coli murG(Ts) at the non‐permissive temperature: transformants were only obtained in the presence of 0.2% arabinose at 42°C and their growth rate was dependent on arabinose concentrations. However, no MurG activity was detected in membranes from the transformant grown in arabinose at 42°C, while MraY activity was normal. This observation led to the development of a membrane‐based scintillation proximity assay for exogenous sources of MurG. Addition of purified E. coli MurG resulted in reconstitution of MurG and peptidoglycan synthesis in these membranes. M... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376527 Mon, 31 Oct 2011 04:00:00 +0100 5376527 http://www.medworm.com/index.php?rid=5376526&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02445.x AbstractProtein tyrosine phosphatase (PTP)‐like proteins exist in many bacteria and are segregated into two major groups: low molecular weight, and conventional. The latter group also has activity as phosphoinositide phosphatases. These two kinds of PTP are suggested to be involved in many aspects of bacterial physiology including stress response, DNA binding proteins, virulence and capsule/cell wall production.By annotation Listeria monocytogenes possesses two potential low molecular weight and two conventional PTPs. Using L. monocytogenes wild‐type (WT) strain 10403S, we have created an in‐frame deletion mutant lacking all four PTPs, as well as four additional complemented strains harboring each of the PTPs. No major physiological differences were observed between the WT and the mu... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376526 Mon, 31 Oct 2011 04:00:00 +0100 5376526 http://www.medworm.com/index.php?rid=5356009&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02444.x AbstractDissimilatory metal‐reducing bacteria, such as Shewanella oneidensis MR‐1, are of great interest for their importance in the biogeochemical cycling of metals and utility in biotechnological processes, such as bioremediation and microbial fuel cells. In order to identify genes necessary for metal reduction, this study constructed a random transposon‐insertion mutant library of MR‐1 and screened it for isolating mutants that were deficient in metal reduction. Examination of approximately 5000 mutants on lactate minimal‐medium plates containing MnO2 resulted in the isolation of one mutant, strain N22‐7, that showed a decreased MnO2‐reduction activity. Determination of a transposon‐insertion site in N22‐7 followed by deletion and complementation experiments revealed t... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5356009 Fri, 28 Oct 2011 07:19:11 +0100 5356009 http://www.medworm.com/index.php?rid=5344014&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02441.x AbstractMicroRNAs (miRNAs) are important modulators of gene expression in eukaryotic cells. However RNAs of the same size in bacteria have not been specifically discussed previously. Here, we provide a library of miRNA‐size RNAs (msRNAs), which were registered by deep sequencing in Streptococcus mutans. Bioinformatic analysis of the whole set revealed more than 900 individual msRNA species. Cellular content of selected msRNAs was verified by qRT‐PCR and Nothern blotting. High abundance and discrete size of the subset of registered msRNAs assume a possibility of their functional significance, though precise biological role of the revealed RNA species in Streptococcus mutans, which is one of the principle causative agents of dental caries, has to be elucidated. (Source: FEMS Microbiology... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344014 Mon, 24 Oct 2011 12:08:47 +0100 5344014 http://www.medworm.com/index.php?rid=5428635&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02443.x AbstractThe Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises pathogenic species associated with different degrees with human infections but also spontaneously fermented dairy products. We aimed therefore at developing a specific identification assay for the SBSEC targeting the 16S rRNA gene comprising a multiplex PCR followed by a differentiating restriction fragment length polymorphisms (RFLP). The multiplex PCR assay was positively applied on 200 SBSEC isolates including reference strains. The assay did not yield false‐positive amplifications with strains of closely related bacteria and isolates of non‐SBSEC streptococci, lactococci, enterococci, and other genera of dairy origin. The downstream RFLP using MseI and XbaI enabled further discrimination of Streptococcu... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5428635 Fri, 21 Oct 2011 04:00:00 +0100 5428635 http://www.medworm.com/index.php?rid=5404953&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02442.x AbstractUnderstanding the molecular basis of acid tolerance in the food‐borne pathogen Listeria monocytogenes is important as this property contributes to survival in the food‐chain and enhances survival within infected hosts. The aim of this study was to identify genes contributing to acid tolerance in L. monocytogenes using transposon mutagenesis and subsequently to elucidate the physiological role of these genes in acid tolerance. One mutant harboring a Tn917 insertion in the thiT gene (formerly lmo1429), which encodes a thiamine (vitamin B1) uptake system, was found to be highly sensitive to acid. The acid‐sensitive phenotype associated with loss of this gene was confirmed with an independently isolated mutant, from which the thiT gene was deleted (∆thiT). Cells of both wild�... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5404953 Fri, 21 Oct 2011 04:00:00 +0100 5404953 http://www.medworm.com/index.php?rid=5344018&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02439.x AbstractOur previous studies indicated that the silkworm model is useful for identifying virulence genes of Staphylococcus aureus, a human pathogenic bacterium. In the present study, we examined the scope of S. aureus virulence factors that can be evaluated using the silkworm model. Gene‐disrupted mutants of the agr locus, arlS gene, and saeS gene, which regulate the expression of cell surface adhesins and hemolysins, exhibited attenuated virulence in silkworms. Mutants of the hla gene encoding α‐hemolysin, the hlb gene encoding β‐hemolysin, and the psmα and psmβ operons encoding cytolysins, however, showed virulence in silkworms indistinguishable from that of the parent strain. Thus, these S. aureus cytolysins are not required for virulence in silkworms. In contrast, the gene‐... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344018 Fri, 21 Oct 2011 04:00:00 +0100 5344018 http://www.medworm.com/index.php?rid=5344017&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02440.x AbstractThe present study was conducted to test the ability of probiotic lactobacilli to alter age‐related immunosenescence in host animals. Senescence‐accelerated mouse prone 1 mice were orally fed heat‐killed Lactobacillus gasseri TMC0356 (TMC0356) for 4 and 8 weeks at dosages of 10 mg day−1 after a 16week period of prefeeding with a standard diet. After 4 and 8 weeks of TMC0356 intervention, splenic activation of natural killer (NK) cells and mRNA expression of cytokines and other immune molecules in the lungs were analyzed. After 4 and 8 weeks, splenic NK cell activities were significantly higher in the TMC0356‐fed mice compared with the control mice (P < 0.05). After 4 weeks, mRNA expression of interleukin‐2 and interferon ‐(α and β) receptor 1 in lung cells isolate... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344017 Fri, 21 Oct 2011 04:00:00 +0100 5344017 http://www.medworm.com/index.php?rid=5344016&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02443.x AbstractThe Streptococcus bovis/Streptococcus equinus complex (SBSEC) comprises pathogenic species associated to different degrees with human infections but also spontaneously fermented dairy products. We aimed therefore at developing a specific identification assay for the SBSEC targeting the 16S rRNA gene comprising a multiplex PCR followed by a differentiating restriction fragment length polymorphisms (RFLP). The multiplex PCR assay was positively applied on 200 SBSEC isolates including reference strains. The assay did not yield false‐positive amplifications with strains of closely related bacteria and isolates of non‐SBSEC streptococci, lactococci, enterococci and other genera of dairy origin. The downstream RFLP using MseI and XbaI enabled further discrimination of S. infantarius/... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344016 Fri, 21 Oct 2011 04:00:00 +0100 5344016 http://www.medworm.com/index.php?rid=5344015&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02442.x AbstractUnderstanding the molecular basis of acid tolerance in the food‐borne pathogen Listeria monocytogenes is important since this property contributes to survival in the food‐chain and enhances survival within infected hosts. The aim of this study was to identify genes contributing to acid tolerance in Listeria monocytogenes using transposon mutagenesis and subsequently to elucidate the physiological role of these genes in acid tolerance. One mutant harboring a Tn917 insertion in the thiT gene (formerly lmo1429), which encodes a thiamine (vitamin B1) uptake system, was found to be highly sensitive to acid. The acid‐sensitive phenotype associated with loss of this gene was confirmed with an independently isolated mutant, from which the thiT gene was deleted (∆thiT). Cells of bot... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344015 Fri, 21 Oct 2011 04:00:00 +0100 5344015 http://www.medworm.com/index.php?rid=5331366&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02438.x AbstractAzoxystrobin (AZ), a strobilurin‐derived fungicide, is known to inhibit mitochondrial respiration in fungi by blocking the electron transport chain in the inner mitochondrial membrane. Germination was strongly inhibited when Botrytis cinerea spore suspension was treated with AZ and the alternative oxidase (AOX) inhibitors, salicylhydroxamic acid (SHAM) and n‐propyl gallate (PG). However, chemical death indicators trypan blue and propidium iodide showed that those spores were still alive. When the spore suspension in the AZ and SHAM solution was replaced with distilled water, the germination rate almost recovered, at least during the first 2 days incubation with AZ and SHAM solution. Any morphological alternation was not detected in the cells treated with AZ and SHAM, especially... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331366 Thu, 20 Oct 2011 06:31:03 +0100 5331366 http://www.medworm.com/index.php?rid=5331372&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02432.x AbstractKlebsiella pneumoniae 287‐w carries three small narrow host range (NHR) plasmids (pIGMS31, pIGMS32 and pIGRK), which could be maintained in several closely related species of Gammaproteobacteria, but not in Alphaproteobacteria. The plasmids contain different mobilization systems (MOB), whose activity in Escherichia coli was demonstrated in the presence of the helper transfer system originating from plasmid RK2. The MOBs of pIGMS31 and pIGMS32 are highly conserved in many bacterial plasmids (members of the MOB family), while the predicted MOB of pIGRK has a unique structure, encoding a protein similar to phage‐related integrases. The MOBs of pIGMS31 and pIGMS32 enabled the transfer of heterologous replicons from E. coli into both gammaproteobacterial and alphaproteobacterial hos... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331372 Mon, 17 Oct 2011 04:00:00 +0100 5331372 http://www.medworm.com/index.php?rid=5331371&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02433.x AbstractHaemophilus parasuis outer membrane protein P2 (OmpP2), the most abundant protein in the outer membrane, has been identified as an antigenic protein and a potential virulence factor. To study the precise function of OmpP2, an ompP2 deficient mutant (ΔompP2) of a H. parasuis serovar 4 clinical strain SC096 was constructed by a modified natural transformation system. Compared to the wild‐type SC096 strain, the ΔompP2 mutant showed a pronounced growth defect and exhibited significantly greater sensitivity to the bactericidal action of porcine and rabbit sera, whereas the complemented strain could restore the growth and serum resistance phenotypes. The results indicated that H. parasuis OmpP2 from SC096 strain is an important surface protein involved in serum resistance. (Source: F... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331371 Mon, 17 Oct 2011 04:00:00 +0100 5331371 http://www.medworm.com/index.php?rid=5331370&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02434.x AbstractThe diversity of the equine fecal bacterial community was evaluated using pyrosequencing of 16S rRNA gene amplicons. Fecal samples were obtained from horses fed cool season grass hay. Fecal bacteria were characterized by amplifying the V4 region of bacterial 16S rRNA gene. Out of 5,898 mean unique sequences, a mean 1,510 operational taxonomic units (OTUs) were identified in the four fecal samples. Equine fecal bacterial richness was higher than reported in humans, but lower than reported in either cattle feces or soil. Bacterial classified sequences were assigned to 16 phyla, of which 10 were present in all samples. The largest number of reads belonged to Firmicutes (43.7% of total bacterial sequences), Verrucomicrobia (4.1%), Proteobacteria (3.8%), and Bacteroidetes (3.7%). The le... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331370 Mon, 17 Oct 2011 04:00:00 +0100 5331370 http://www.medworm.com/index.php?rid=5331369&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02435.x This study shows that bacteria using different chitin degradation mechanisms can co‐exist by formation of a mixed‐species biofilm. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331369 Mon, 17 Oct 2011 04:00:00 +0100 5331369 http://www.medworm.com/index.php?rid=5331368&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02437.x AbstractMicrobial communities that thrive in subterranean consolidated sediments are largely unknown owing to the difficulty of extracting DNA. As this difficulty is often attributed to DNA binding onto the silica‐bearing sediment matrix, we developed a DNA extraction method for consolidated sediment from the deep subsurface in which silica minerals were dissolved by being heated under alkaline conditions. NaOH concentrations (0.07 and 0.33 N), incubation temperatures (65 and 94°C), and incubation times (30‐90 min) before neutralization were evaluated based on the copy number of extracted prokaryotic DNA. Prokaryotic DNA was detected by quantitative PCR analysis after heating the sediment sample at 94°C in 0.33 N NaOH solution for 50 to 80 min. The results of 16S rRNA gene sequence a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331368 Mon, 17 Oct 2011 04:00:00 +0100 5331368 http://www.medworm.com/index.php?rid=5331367&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02436.x AbstractThe Cpx‐envelope stress system coordinates the expression and assembly of surface structures important for the virulence of Gram‐negative pathogenic bacteria. It is comprised of the membrane anchored sensor kinase CpxA, the cytosolic response regulator CpxR and the accessory protein CpxP. Characteristic of the group of two‐component systems, the Cpx system responds to a broad range of stimuli envelope including pH, salt, metals, lipids and misfolded proteins that cause perturbation in the envelope. Moreover, the Cpx system has been linked to inter‐kingdom signalling and bacterial cell death. However, although signal specificity has been assumed, for most signals the mechanism of signal integration is not understood. Recent structural and functional studies provide the first... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331367 Mon, 17 Oct 2011 04:00:00 +0100 5331367 http://www.medworm.com/index.php?rid=5311520&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02431.x AbstractSalmonella Dakar and Salmonella Telaviv bacteria belong to serogroup O:28, which represents 107 serovars and possesses only the epitope O28. Salmonella Telaviv has the subfactors O281 and O282, whereas Salmonella Dakar has O281 and O283. So far, only limited serological and immunological information for this serogroup is available in the literature. Knowledge of the structures of their O‐polysaccharides and the immunochemical investigations performed in this work, allowed to reveal the nature of subfactor O281 as attributed to the presence of 3‐linked (or 3,4‐disubstittuted) α‐D‐GalpNAc in the main chains of S. Dakar and S. Telaviv O‐polysaccharides.. An explanation for the cross‐reactions between Salmonella enterica O28 O‐antigens and other Salmonella O‐polysacc... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5311520 Thu, 13 Oct 2011 15:57:45 +0100 5311520 http://www.medworm.com/index.php?rid=5376528&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02431.x AbstractSalmonellaDakar and SalmonellaTelaviv bacteria belong to serogroup O:28, which represents 107 serovars and possesses only the epitope O28. SalmonellaTelaviv has the subfactors O281 and O282, whereas S. Dakar has O281 and O283. So far, only limited serological and immunological information for this serogroup is available in the literature. Knowledge of the structures of their O‐polysaccharides and the immunochemical investigations performed in this work allowed to reveal the nature of subfactor O281 as attributed to the presence of 3‐linked (or 3,4‐disubstituted) α‐d‐GalpNAc in the main chains of S. Dakar and S. Telaviv O‐polysaccharides. An explanation for the cross‐reactions between Salmonella entericaO28 O‐antigens and other SalmonellaO‐polysaccharides and th... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5376528 Tue, 11 Oct 2011 04:00:00 +0100 5376528 http://www.medworm.com/index.php?rid=5294034&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02428.x AbstractWallemia sebi is a xerotolerant, ubiquitous, food‐borne, mycotoxigenic fungus. An ethanol extract of its mycelium demonstrated a strong hemolytic activity, which was further enhanced at high salt concentrations in the growth medium. Characterization of the extract using gas chromatography–mass spectrometry revealed a mixture of sterols and unsaturated fatty acids, indicating the latter as responsible for the hemolytic activity. The lytic activity of the extract is here studied using red blood cells and artificial small lipid vesicles with various lipid compositions. This shows concentration‐dependent hemolysis, and preferential activity towards lipid membranes with greater fluidity. The W. sebi lytic activity on mammalian erythrocytes shows its potential involvement in the f... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5294034 Fri, 07 Oct 2011 23:50:04 +0100 5294034 http://www.medworm.com/index.php?rid=5344022&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02430.x This study showed that eGFP‐PilACt fusion protein was able efficiently to label the EPS of M. xanthus, providing evidence for the first time of the direct interaction between the PilA protein and EPS under native conditions. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344022 Thu, 06 Oct 2011 04:00:00 +0100 5344022 http://www.medworm.com/index.php?rid=5331373&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02429.x This study was designed to evaluate gene expression patterns of the planktonic and biofilm cells of Staphylococcus aureus and SalmonellaTyphimurium in trypticase soy broth adjusted to pH 5.5 and pH 7.3. The planktonic and biofilm cells of multiple antibiotic‐resistant S. aureus (S. aureusR) and S. Typhimurium (S. TyphimuriumR) were more resistant to β‐lactams than those of antibiotic‐susceptible S. aureus (S. aureusS) and S. Typhimurium (S. TyphimuriumS) at pH 5.5 and pH 7.3. The relative gene expression levels of norB, norC, and mdeA genes were increased by 7.0‐, 4.7‐, and 4.6‐fold, respectively, in the biofilm cells of S. aureusS grown at pH 7.3, while norB, norC, mdeA, sec, seg, sei, sel, sem, sen, and seo genes were stable in the biofilm cells of S. aureusR. This... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5331373 Thu, 06 Oct 2011 04:00:00 +0100 5331373 http://www.medworm.com/index.php?rid=5294036&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02429.x This study was designed to evaluate gene expression patterns of the planktonic and biofilm cells of Staphylococcus aureus and Salmonella Typhimurium in trypticase soy broth (TSB) adjusted to pH 5.5 and pH 7.3. The planktonic and biofilm cells of multiple antibiotic‐resistant S. aureus (S. aureusR) and S. Typhimurium (S. TyphimuriumR) were more resistant to β‐lactams than those of antibiotic‐susceptible S. aureus (S. aureusS) and S. Typhimurium (S. TyphimuriumS) at pH 5.5 and pH 7.3. The relative gene expression levels of norB, norC, and mdeA genes were increased by 7.0‐fold, 4.7‐fold, and 4.6‐fold, respectively, in the biofilm cells of S. aureusS grown at pH 7.3, while norB, norC, mdeA, sec, seg, sei, sel, sem, sen, and seo genes were stable in the biofilm cells of S. aureusR.... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5294036 Thu, 06 Oct 2011 04:00:00 +0100 5294036 http://www.medworm.com/index.php?rid=5294035&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02430.x This study showed that eGFP‐PilACt fusion protein was able to efficiently label the EPS of M. xanthus and for the first time provided evidence for the direct interaction between the PilA protein and EPS under native conditions. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5294035 Thu, 06 Oct 2011 04:00:00 +0100 5294035 http://www.medworm.com/index.php?rid=5282072&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02427.x AbstractSelenomonas ruminantium strains were isolated from sheep rumen and their significance for fiber digestion was evaluated. Based on the phylogenetic classification, two clades of S. ruminantium (clades I and II) were proposed. Clade II is newly found, as it comprised only new isolates that were phylogenetically distant from the type strain, while all of the known isolates were grouped in the major clade I. More than half of clade I isolates displayed CMCase activity with no relation to the degree of bacterial adherence to fibers. Although none of the isolates digested fiber in monoculture, they stimulated fiber digestion when cocultured with Fibrobacter succinogenes, and there was an enhancement of propionate production. The extent of such synergy depended on the clade, with higher d... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282072 Tue, 04 Oct 2011 15:37:10 +0100 5282072 http://www.medworm.com/index.php?rid=5404954&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02426.x AbstractPer‐ARNT‐Sim (PAS) domains are important signalling modules that possibly monitor changes in various stimuli such as light. For the majority of PAS domains that have been identified by sequence similarity, the biological function of the signalling pathways has not yet been experimentally investigated. Thirty‐three PAS proteins were discovered in Xanthomonas campestris pv. campestris (Xcc) by genome/proteome analysis. Thirteen PAS proteins were identified as contributing to light signalling and Xcc growth, motility or virulence using molecular genetics and bioinformatics methods. The PAS domains played important roles in light signalling to regulate the growth, motility and virulence of Xcc. They might be regulated by not only light quality (wavelength) but also quantity (inte... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5404954 Mon, 03 Oct 2011 04:00:00 +0100 5404954 http://www.medworm.com/index.php?rid=5344021&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02425.x AbstractMajor questions concerning the sources and mechanisms of the reduction of nitric oxide by enteric bacteria remain unresolved. The membrane‐associated nitrate reductase is the major source of NO generated from nitrite, but at least one other source remains to be identified. Nitrite reductases are primarily detoxification systems that decrease rather than increase the accumulation of NO in the cytoplasm. Whether they also catalyze NO formation is unresolved. The FNR protein that regulates transitions between aerobic and anaerobic growth is inactivated as a consequence of nitrosative damage, but we challenge the idea that FNR is a physiologically relevant sensor of NO, except under the most severe nitrosative stress. As none of the three enzymes that reduce NO account for the majori... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344021 Mon, 03 Oct 2011 04:00:00 +0100 5344021 http://www.medworm.com/index.php?rid=5344019&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02424.x AbstractThe quality and yield of extracted DNA are critical for the majority of downstream applications in molecular biology. Moreover, molecular techniques such as quantitative real‐time PCR (qPCR) are becoming increasingly widespread; thus, validation and cross‐laboratory comparison of data require standardization of upstream experimental procedures. DNA extraction methods depend on the type and size of starting material(s) used. As such, the extraction of template DNA is arguably the most significant variable when cross‐comparing data from different laboratories. Here, we describe a reliable, inexpensive and rapid method of DNA purification that is equally applicable to small or large scale or high‐throughput purification of DNA. The protocol relies on a CTAB‐based buffer for ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344019 Mon, 03 Oct 2011 04:00:00 +0100 5344019 http://www.medworm.com/index.php?rid=5282075&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02426.x AbstractPer‐ARNT‐Sim (PAS) domains are important signaling modules that possibly monitor changes in various stimuli such as light. For the majority of PAS domains that have been identified by sequence similarity, the biological function of the signaling pathways has not yet been experimentally investigated. Thirty‐three PAS proteins were discovered in Xanthomonas campestris pv. campestris (Xcc) by genome/proteome analysis. Thirteen PAS proteins were identified as contributing to light signaling and Xcc growth, motility or virulence using molecular genetics and bioinformatics methods. The PAS domains played important roles in light signaling to regulate the growth, motility and virulence of Xcc. They might be regulated by not only light quality (wavelength) but also quantity (intensit... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282075 Mon, 03 Oct 2011 04:00:00 +0100 5282075 http://www.medworm.com/index.php?rid=5282074&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02425.x AbstractMajor questions concerning the sources and mechanisms of reduction of nitric oxide by enteric bacteria remain unresolved. The membrane‐associated nitrate reductase is the major source of NO generated from nitrite, but at least one other source remains to be identified. Nitrite reductases are primarily detoxification systems that decrease rather than increase the accumulation of NO in the cytoplasm. Whether they also catalyse NO formation is unresolved. The FNR protein that regulates transitions between aerobic and anaerobic growth is inactivated as a consequence of nitrosative damage, but we challenge the idea that FNR is a physiologically relevant sensor of NO, except under the most severe nitrosative stress. As none of the three enzymes that reduce NO account for the majority o... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282074 Mon, 03 Oct 2011 04:00:00 +0100 5282074 http://www.medworm.com/index.php?rid=5282073&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02424.x AbstractThe quality and yield of extracted DNA are critical for the majority of downstream applications in molecular biology. Moreover, molecular techniques such as quantitative real‐time PCR (qPCR) are becoming increasingly widespread, thus, validation and cross‐laboratory comparison of data requires standardisation of upstream experimental procedures. DNA extraction methods depend on the type and size of starting material(s) used. As such, the extraction of template DNA is arguably the most significant variable when cross‐comparing data from different laboratories. Here, we describe a reliable, inexpensive and rapid method of DNA purification that is equally applicable to small or large scale or high‐throughput purification of DNA. The protocol relies on a CTAB‐based buffer for... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282073 Mon, 03 Oct 2011 04:00:00 +0100 5282073 http://www.medworm.com/index.php?rid=5269736&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02421.x AbstractAvian pathogenic Escherichia coli (APEC) are bacteria associated with extraintestinal diseases in poultry. A method to generate markerless deletions of APEC genome is described. Lambda Red recombination is used to introduce a LoxP cassette (loxP‐rpsL‐neo‐loxP) containing the rpsL gene for streptomycin sensitivity and the neo gene for kanamycin/ neomycin resistance into the APEC genome with attendant deletion of a desired chromosomal gene. The loxP sites are incorporated into primers used to amplify the rpsL‐neo marker during the construction of the LoxP cassette making the method rapid and efficient. The cassette is specifically integrated into the fiu gene or intergenic region 2051‐52 and the Cre/lox system is used to remove the marker hence deletion of the drug‐resist... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5269736 Sat, 01 Oct 2011 01:21:37 +0100 5269736 http://www.medworm.com/index.php?rid=5311521&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02422.x AbstractIt is expected that Mannheimia hemolyticaA1 expresses a particular collection of genes during infection in the host. The bacterial gene products are produced in the in vivo environment to facilitate growth and survival. Here, we examined gene expression by M. hemolyticaA1 in the bovine host after 6 days of infection. Total RNA from M. hemolyticaA1 recovered from pneumonic lungs of two animals was used to produce cDNA to screen a custom M. hemolyticaA1 microarray. The expression profile was compared to a RNA sample from an in vitro grown culture. The data showed that 44 genes were differentially expressed by more than eightfold when compared with the in vitro sample. Seventeen genes were found to have higher expression in vivo and 27 genes had lower expression. Several virulence... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5311521 Tue, 27 Sep 2011 04:00:00 +0100 5311521 http://www.medworm.com/index.php?rid=5302076&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02421.x AbstractAvian pathogenic Escherichia coli (APEC) are bacteria associated with extraintestinal diseases in poultry. A method to generate markerless deletions of APEC genome is described. Lambda Red recombination is used to introduce a LoxP cassette (loxP‐rpsL‐neo‐loxP) containing the rpsL gene for streptomycin sensitivity and the neo gene for kanamycin/neomycin resistance into the APEC genome, with attendant deletion of a desired chromosomal gene. The loxP sites are incorporated into primers used to amplify the rpsL‐neo marker during the construction of the LoxP cassette, making the method rapid and efficient. The cassette is specifically integrated into the fiu gene or intergenic region 2051‐52, and the Cre/lox system is used to remove the marker, hence deletion of the drug‐res... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5302076 Tue, 27 Sep 2011 04:00:00 +0100 5302076 http://www.medworm.com/index.php?rid=5269739&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02422.x AbstractObjective:It is expected that Mannheimia haemolytica A1 expresses a particular collection of genes during infection in the host. The bacterial gene products are produced in the in vivo environment to facilitate growth and survival. Here, we examined gene expression by M. haemolytica A1 in the bovine host after 6 days of infection.Methods:Total RNA from M. haemolytica A1 recovered from pneumonic lungs of two animals was used to produce cDNA to screen a custom M. haemolytica A1 microarray. The expression profile was compared to a RNA sample from an in vitro grown culture.Results:The data showed that 44 genes were differentially expressed by more than 8 fold when compared to the in vitro sample. Seventeen genes were found to have higher expression in vivo and 27 genes had lower expres... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5269739 Tue, 27 Sep 2011 04:00:00 +0100 5269739 http://www.medworm.com/index.php?rid=5269737&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02423.x AbstractNattokinase (subtilisin NAT, NK) is a relatively effective microbial fibrinolytic enzyme that has been identified and characterised from Bacillus natto. In the current report, DNA family shuffling was applied to improve the fibrinolytic activity of nattokinase. Three homologous genes from Bacillus nattoAS 1.107, Bacillus amyloliquefaciensCICC20164 and Bacillus licheniformisCICC 10092 were shuffled to generate a mutant library. A plate‐based method was used to screen the mutant libraries for improved activity. After three rounds of DNA shuffling, one desirable mutant with sixteen amino acid substitutions was obtained. The mutant enzyme was purified and characterised. The kinetic measurements showed that the catalytic efficiency of the mutant NK was approximately 2.3 times higher t... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5269737 Tue, 27 Sep 2011 04:00:00 +0100 5269737 http://www.medworm.com/index.php?rid=5246921&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02420.x AbstractHIC6 is a group‐3 LEA (late embryogenesis abundant) protein found in Chlorella vulgaris. In the Antarctic strain NJ‐7 of this unicellular green alga, it is encoded by a tandem array of 5 hiC6 genes (designated as NJ7hiC6‐1, ‐2, ‐3, ‐4 and ‐5); in the temperate strain UTEX259, it is encoded by 4 hiC6 genes in tandem (designated as 259hiC6‐1, ‐2, ‐3 and ‐4). Except NJ7hiC6‐3 and ‐4, the encoding regions of all other hiC6 genes differ from each other by 2‐19 bp in each strain. Based on RT‐PCR and sequencing of total hiC6cDNA clones, the relative transcript abundance was evaluated of each hiC6 gene. NJ7hiC6‐2 and 259hiC6‐2 were not expressed or expressed at low levels, while 259hiC6‐1 and NJ7hiC6‐3/4 exhibited the highest hiC6 transcript levels in ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5246921 Fri, 23 Sep 2011 15:07:19 +0100 5246921 http://www.medworm.com/index.php?rid=5234248&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02418.x AbstractUnderstanding the ecology of methanogens in natural and engineered environments is a prerequisite to predicting or managing methane emissions. In the present study, a novel high‐throughput fingerprint method was developed for determining methanogen diversity and relative abundance within environmental samples. The method described here, designated amplicon length heterogeneity PCR of the mcrA gene (LH‐mcrA), is based on the natural length variation in the mcrA gene. The mcrA gene encodes the alpha‐subunit of the methyl coenzyme M reductase, which is involved in the terminal step of methane production by methanogens. The methanogenic communities from stored swine and dairy manures were distinct from each other. To validate the method, methanogenic communities in a plug‐flow ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5234248 Tue, 20 Sep 2011 05:06:38 +0100 5234248 http://www.medworm.com/index.php?rid=5282076&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02419.x AbstractIt has been demonstrated previously that Enterococcus faecalis produces secreted endoglycosidases that enable the bacteria to remove N‐linked glycans from glycoproteins. One enzyme potentially responsible for this activity is EF0114, comprising a typical GH18 endoglycosidase domain and a GH20 domain. We have analyzed the other candidate, EF2863, and show that this predicted single domain GH18 protein is an endo‐β‐N‐acetylglucosaminidase. EF2863 hydrolyzes the glycosidic bond between two N‐acetylglucosamines (GlcNAc) in N‐linked glycans of the high‐mannose and hybrid type, releasing the glycan and leaving one GlcNAc attached to the protein. The activity of EF2863 is similar to that of the well known deglycosylating enzyme EndoH from Streptomyces plicatus. According to... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282076 Tue, 20 Sep 2011 04:00:00 +0100 5282076 http://www.medworm.com/index.php?rid=5246922&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02419.x AbstractIt has previously been demonstrated that Enterococcus faecalis produces secreted endoglycosidases that enable the bacterium to remove N‐linked glycans from glycoproteins. One enzyme potentially responsible for this activity is EF0114, comprising a typical GH18 endoglycosidase domain and a GH20 domain. We have analyzed the other candidate, EF2863, and show that this predicted single domain GH18 protein is an endo‐β‐N‐acetylglucosaminidase. EF2863 hydrolyzes the glycosidic bond between two N‐acetylglucosamines (GlcNAc) in N‐linked glycans of the high‐mannose and hybrid type, releasing the glycan and leaving one GlcNAc attached to the protein. The activity of EF2863 is similar to that of the well‐known deglycosylating enzyme EndoH from Streptomyces plicatus. According... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5246922 Tue, 20 Sep 2011 04:00:00 +0100 5246922 http://www.medworm.com/index.php?rid=5321916&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02416.x AbstractThe cold acclimatization response in many bacterial species is a tightly regulated process, which ensures the correct folding of macromolecules. In enterobacteria, this response is in part dependent on polynucleotide phosphorylase, which is encoded by the gene pnp. Based on transcriptional analysis of the pnp locus of Salmonella enterica serovar Typhimurium, we show that pnp and the adjacent membrane lipoprotein nlpI gene form an operon with both genes contributing independently to the cold acclimatization response at 15 °C. Our findings thereby define a new role for NlpI in bacterial cold acclimatization. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5321916 Fri, 16 Sep 2011 04:00:00 +0100 5321916 http://www.medworm.com/index.php?rid=5282079&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02415.x AbstractFour lytic bacteriophages designated as φVh1, φVh2, φVh3, and φVh4 were isolated from commercial shrimp hatcheries, possessing broad spectrum of infectivity against luminescent Vibrio harveyi isolates, considering their potential as biocontrol agent of luminescent bacterial disease in shrimp hatcheries, and were characterized by electron microscopy, genomic analysis, restriction enzyme analysis (REA), and pulsed‐field gel electrophoresis (PFGE). Three phages φVh1, φVh2, and φVh4 had an icosahedral head of 60–115 nm size with a long, noncontractile tail of 130–329 × 1–17 nm, belonged to the family Siphoviridae. φVh3 had an icosahedral head (72 ± 5 nm) with a short tail (27 × 12 nm) and belonged to Podoviridae. REA with DraI and PFGE of genomic DNA digest... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282079 Fri, 16 Sep 2011 04:00:00 +0100 5282079 http://www.medworm.com/index.php?rid=5282078&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02417.x AbstractThe cell wall is responsible for cell integrity and the maintenance of cell shape in bacteria. The Gram‐positive bacterial cell wall consists of a thick peptidoglycan layer located on the outside of the cytoplasmic membrane. Bacterial cell membranes, like eukaryotic cell membranes, are known to contain domains of specific lipid and protein composition. Recently, using the membrane‐binding fluorescent dye FM4‐64, helix‐like lipid structures extending along the long axis of the cell and consisting of negatively charged phospholipids were detected in the rod‐shaped bacterium Bacillus subtilis. It was also shown that the cardiolipin‐specific dye, nonyl acridine orange (NAO), is preferentially distributed at the cell poles and in the septal regions in both Escherichia coli a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282078 Fri, 16 Sep 2011 04:00:00 +0100 5282078 http://www.medworm.com/index.php?rid=5234251&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02415.x AbstractFour lytic bacteriophages designated as ϕVh1, ϕVh2, ϕVh3 and ϕVh4 isolated from commercial shrimp hatcheries, possessing broad spectrum of infectivity against luminescent V. harveyi isolates, considering their potential as biocontrol agent of luminescent bacterial disease (LBD) in shrimp hatcheries, were characterized by electron microscopy, genomic analysis, restriction enzyme analysis (REA) and pulsed field gel electrophoresis (PFGE). Three phages ϕVh1, ϕVh2 and ϕVh4 had an icosahedral head of 60‐115nm size with long, non‐contractile tail of 130‐329 nm x 1‐17 nm, belonged to the family Siphoviridae. ϕVh3 had an icosahedral head (72±5nm) with a short tail (27nm x 12nm) and belonged to Podoviridae. REA with DraI and PFGE of genomic DNA digested with ScaI a... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5234251 Fri, 16 Sep 2011 04:00:00 +0100 5234251 http://www.medworm.com/index.php?rid=5234250&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02416.x AbstractThe cold acclimatization response in many bacterial species is a tightly regulated process, which ensures the correct folding of macromolecules. In enterobacteria this response is in part dependent on polynucleotide phosphorylase, which is encoded by the gene pnp. Based on transcriptional analysis of pnp locus of Salmonella enterica serovar Typhimurium we show that pnp and the adjacent membrane lipoprotein nlpI gene form an operon with both genes contributing independently to the cold acclimatization response at 15°C. Our findings thereby define a new role for NlpI in bacterial cold acclimatization. (Source: FEMS Microbiology Letters) FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5234250 Fri, 16 Sep 2011 04:00:00 +0100 5234250 http://www.medworm.com/index.php?rid=5234249&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02417.x AbstractThe cell wall is responsible for cell integrity and the maintenance of cell shape in bacteria. The Gram‐positive bacterial cell wall consists of a thick peptidoglycan layer located on the outside of the cytoplasmic membrane. Bacterial cell membranes, like eukaryotic cell membranes, are known to contain domains of specific lipid and protein composition. Recently, using the membrane binding fluorescent dye FM4‐64, helix‐like lipid structures extending along the long axis of the cell and consisting of negatively charged phospholipids were detected in the rod‐shaped bacterium Bacillus subtilis. It was also shown that the cardiolipin‐specific dye, NAO, is preferentially distributed at the cell poles and in the septal regions in both Escherichia coli and B. subtilis. These resu... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5234249 Fri, 16 Sep 2011 04:00:00 +0100 5234249 http://www.medworm.com/index.php?rid=5218225&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02414.x AbstractLactococcus garvieae, the pathogenic species in the genus Lactococcus, is recognized as an emerging pathogen in fish, animals, and humans. Despite the widespread distribution and emerging clinical significance of L. garvieae, little is known about the genomic content of this microorganism. Suppression subtractive hybridization (SSH) was performed to identify genomic differences between L. garvieae and L. lactis subsp. lactis, its closest phylogenetic neighbor and the type species of the genus Lactococcus. Twenty‐seven clones were specific to L. garvieae and were highly different from L. lactis in their nucleotide and protein sequences. L. garvieae primer sets were subsequently designed for two of these clones corresponding to a pyrH gene and a novel DNA signature for application ... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5218225 Wed, 14 Sep 2011 11:20:41 +0100 5218225 http://www.medworm.com/index.php?rid=5344020&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02414.x AbstractLactococcus garvieae, the pathogenic species in the genus Lactococcus, is recognized as an emerging pathogen in fish, animals, and humans. Despite the widespread distribution and emerging clinical significance of L. garvieae, little is known about the genomic content of this microorganism. Suppression subtractive hybridization was performed to identify the genomic differences between L. garvieae and Lactococcus lactis ssp. lactis, its closest phylogenetic neighbor, and the type species of the genus Lactococcus. Twenty‐seven clones were specific to L. garvieae and were highly different from Lactococcus lactis in their nucleotide and protein sequences. Lactococcus garvieae primer sets were subsequently designed for two of these clones corresponding to a pyrH gene and a novel DNA... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5344020 Wed, 14 Sep 2011 04:00:00 +0100 5344020 http://www.medworm.com/index.php?rid=5282081&cid=s_32050_77_f&fid=32050&url=http%3A%2F%2Fdx.doi.org%2F10.1111%252Fj.1574-6968.2011.02410.x AbstractPolyethylene glycol (PEG)‐induced cell fusion is a promising method to transfer larger DNA from one cell to another than conventional genetic DNA transfer systems. The laboratory strain Bacillus subtilis 168 contains a restriction (R) and modification (M) system, BsuM, which recognizes the sequence 5′‐CTCGAG‐3′. To study whether the BsuM system affects DNA transfer by the PEG‐induced cell fusion between R+M+ and R−M− strains, we examined transfer of plasmids pHV33 and pLS32neo carrying no and eight BsuM sites, respectively. It was shown that although the transfer of pLS32neo but not pHV33 from the R−M− to R+M+ cells was severely restricted, significant levels of transfer of both plasmids from the R+M+ to R−M− cells were observed. The latter result shows that... FEMS Microbiology Letters journals http://www.medworm.com/rss/comments.php?id=5282081 Wed, 14 Sep 2011 04:00:00 +0100 5282081