Applied and Environmental Microbiology
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Elimination of glycerol production in anaerobic cultures of Saccharomyces cerevisiae engineered for use of acetic acid as electron acceptor.
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This study provides a proof of principle for the potential of this metabolic engineering strategy to improve ethanol yields, eliminate glycerol production and partially convert acetate, which is a well known inhibitor of yeast performance in lignocellulosic hydrolysates, to ethanol. Further research should address kinetic aspects of acetate reduction and the effect of the elimination of glycerol production on cellular robustness (e.g. osmotolerance).
PMID: 19915031 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Guadalupe Medina V, Almering MJ, van Maris AJ, Pronk JT Tags: Appl Environ Microbiol Source Type: journals
Quantification of cyprinid herpesvirus-3 (CyHV-3) in environmental water using an external standard virus.Email this article to a colleague.
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Cyprinid herpesvirus-3 (CyHV-3), a lethal DNA virus that spreads in natural lakes and rivers, infects common carp and koi. We established a quantification method for CyHV-3 that includes a viral concentration method and quantitative PCR combined with an external standard virus. Viral concentration methods were compared using cation-coated filters and ultrafiltration. The recovery of virus-like particles was similar in both methods (cation-coated filter, 44 +/- 19%, n = 3; ultrafiltration, 50 +/- 3%, n = 3); however, the former method was faster and more suitable for routine determinations. The recovery of seeded CyHV-3...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Honjo MN, Minamoto T, Matsui K, Uchii K, Yamanaka H, Suzuki AA, Kohmatsu Y, Iida T, Kawabata Z Tags: Appl Environ Microbiol Source Type: journals
Identification of the BamVW two-component system involved in transcriptional regulation of aromatic degradation in Geobacter metallireducens.Email this article to a colleague.
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Regulation of aromatic degradation in obligate anaerobes was studied in the Fe(III)-respiring model organism Geobacter metallireducens GS-15. A two-component system and a sigma(54)-dependent promoter were identified that are both involved in the regulation of the gene coding for benzoate-coenzyme A ligase, catalyzing the initial step of benzoate degradation.
PMID: 19915033 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Juárez JF, Zamarro MT, Barragán MJ, Blázquez B, Boll M, Kuntze K, García JL, Díaz E, Carmona M Tags: Appl Environ Microbiol Source Type: journals
Emergence of cell-wall protease in the Streptococcus thermophilus population.Email this article to a colleague.
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Streptococcus thermophilus is perceived as a recently emerged food bacterium that evolved from a commensal ancestor by loss and gain of functions. Here, we provide data allowing a better understanding of this evolutionary scheme. A MLST approach that we developed showed that S. thermophilus diverges significantly from its potential ancestors of the salivarius group and displays a low allelic variability, confirming its likely recent emergence. An analysis of the origin and dissemination of prtS gene was carried out within this evolutionary scheme. This gene encodes protease that allows a better growth in milk, by facil...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Delorme C, Bartholini C, Bolotine A, Ehrlich SD, Renault P Tags: Appl Environ Microbiol Source Type: journals
Integrated Bioprocessing for the pH-Dependent Production of 4-Valerolactone from Levulinate in Pseudomonas putida KT2440.Email this article to a colleague.
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Enzymes are powerful biocatalysts capable of performing specific chemical transformations under mild conditions. Yet as catalysts they remain subject to the laws of thermodynamics, namely that they cannot catalyze chemical reactions beyond equilibrium. Here we report the phenomenon and application of using extracytosolic enzymes and medium conditions such as pH to catalyze metabolic pathways beyond their intracellular catalytic limitations. This methodology, termed "integrated bioprocessing" because it integrates intracellular and extracytosolic catalysis, was applied to a lactonization reaction in Pseudomonas putida f...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Martin CH, Wu D, Prather KL Tags: Appl Environ Microbiol Source Type: journals
Nanosized iron oxide colloids strongly enhance microbial iron reduction.Email this article to a colleague.
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Microbial iron reduction is considered to be a significant subsurface process. The rate-limiting bioavailability of the insoluble iron oxyhydroxides, however, is a topic for debate. Surface area and mineral structure are recognized as crucial parameters for microbial reduction rates of bulk, macroaggregate iron minerals. However, a significant fraction of iron oxide minerals in the subsurface is supposed to be present as nanosized colloids. We therefore studied the role of colloidal iron oxides in microbial iron reduction. In batch growth experiments with Geobacter sulfurreducens, colloids of ferrihydrite (hydrodynamic...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Bosch J, Heister K, Hofmann T, Meckenstock RU Tags: Appl Environ Microbiol Source Type: journals
The Missing Link in LAS Surfactant Degradation: 4-Sulfoacetophenone as a Transient Intermediate in the Degradation of 3-(4-Sulfophenyl)butyrate by Comamonas testosteroni KF-1.Email this article to a colleague.
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Biodegradation of the laundry surfactant linear alkylbenzenesulfonate (LAS) involves complex bacterial communities. The known heterotrophic community has two tiers. Firstly, all LAS congeners are oxygenated and oxidized to about 50 sulfophenylcarboxylates (SPC). Secondly, the SPCs are mineralized. Comamonas testosteroni KF-1 mineralizes 3-(4-sulfophenyl)butyrate (3-C4-SPC). During growth of strain KF-1 with 3-C4-SPC, two transient intermediates were detected in the culture medium. One intermediate was identified as 4-sulfoacetophenone (SAP) [4-acetylbenzenesulfonate] by NMR. The other was 4-sulfophenol (SP). This infor...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Schleheck D, von Netzer F, Fleischman T, Rentsch D, Huhn T, Cook AM, Kohler HP Tags: Appl Environ Microbiol Source Type: journals
A probabilistic model of growth, division, and mortality of microbial cells.Email this article to a colleague.
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A PROBABILISTIC MODEL OF GROWTH, DIVISION, AND MORTALITY OF MICROBIAL CELLS.
Appl Environ Microbiol. 2009 Nov 13;
Authors: Horowitz J, Normand MD, Corradini MG, Peleg M
After a short time interval of length deltat during microbial growth and mortality, an individual cell can be found divided with a probability Pd(t)deltat, dead with a probability Pm(t)deltat, or alive but undivided with probability 1- (Pd (t) + Pm(t))deltat. These probabilities may change with the state of the population and the habitat's properties, and are therefore functions of time. This translates into a model that is presented in stochast...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Horowitz J, Normand MD, Corradini MG, Peleg M Tags: Appl Environ Microbiol Source Type: journals
The role of extracellular polymeric substances in the surface chemical reactivity of Hymenobacter aerophilus, a psychrotolerant bacterium.Email this article to a colleague.
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Bacterial surface layers, such as extracellular polymeric substances (EPS), are known to play an important role in metal sorption and biomineralization, however there have been very few studies investigating how environmentally-induced changes in EPS production affect the cell's surface chemistry and reactivity. Acid-base titrations, cadmium adsorption assays and FT-IR were used to characterize the surface reactivity of Hymenobacter aerophilus cells with intact EPS (WC) or stripped of EPS (SC), and purified EPS alone. Linear programming modeling of titration data showed SC to possess functional groups corresponding to ...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Baker MG, Lalonde SV, Konhauser KO, Foght JM Tags: Appl Environ Microbiol Source Type: journals
Traceability of marketable Japanese shoro in New Zealand: Using multiplex PCR to exploit phylogeographic variation amongst taxa in the Rhizopogon subgenus roseoli.Email this article to a colleague.
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In this study, the ITS1-5.8S-ITS2 rRNA (ITS) region was used to examine the phylogenetic relationships of R. roseolus and other closely related fungi belonging to R. subgenus roseoli to determine the genetic basis for phenotypic differences amongst R. roseolus from different geographic regions. Phylogenetic comparison revealed phylogeographic variation within R. subgenus roseoli. Collections from the United States and Europe grouped into four distinct clades. Rhizopogon roseolus found in New Zealand were closely related to those from the United States, likely due to introduction of Pinus radiata from its native California,...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Visnovsky SB, Guerin-Laguette A, Wang Y, Pitman AR Tags: Appl Environ Microbiol Source Type: journals
TOLERANCE TO HOP ISO-{alpha}-ACIDS IN YEAST INVOLVES VACUOLAR SEQUESTRATION, AND ACTIVE TRANSPORT.Email this article to a colleague.
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The hop plant, Humulus lupulus L., contains an exceptionally high content of secondary metabolites, the hop alpha-acids, which possess a range of beneficial properties including antiseptic action. Studies performed on the mode of action of hop iso-alpha-acids have hitherto been restricted to lactic acid bacteria. The present study investigates molecular mechanisms of hop iso-alpha-acid resistance in the model eukaryote Saccharomyces cerevisiae. Growth inhibition occurred at concentrations of hop iso-alpha-acids that were an order of magnitude higher than those found with hop-tolerant prokaryotes. Chemostat-based transc...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Hazelwood LA, Walsh MC, Pronk JT, Daran JM Tags: Appl Environ Microbiol Source Type: journals
Expression of the Clostridium botulinum A2 Neurotoxin Gene Cluster Proteins and Characterization of the A2 Complex.Email this article to a colleague.
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Clostridium botulinum subtype A2 possesses a botulinum neurotoxin type A (BoNT/A) gene cluster consisting of an orfX cluster containing open reading frames (orfs) of unknown functions. To better understand the association between the BoNT/A2 complex proteins, first, the orfX cluster proteins (ORFX1, ORFX3, P47 and middle part of NTNH) from C. botulinum A2 (strain Kyoto F) and the NTNH of an A1 strain (ATCC 3502) were expressed using either E. coli or C. botulinum expression systems. Polyclonal antibodies against individual orfX cluster proteins were prepared by immunizing rabbits and mice against the expressed proteins...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Lin G, Tepp WH, Pier CL, Jacobson MJ, Johnson EA Tags: Appl Environ Microbiol Source Type: journals
Tertiary Structure and Characterization of a Glycoside Hydrolase Family 44 Endoglucanase from Clostridium acetobutylicum.Email this article to a colleague.
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A gene encoding a glycoside hydrolase family 44 (GH44) protein from Clostridium aceto-butylicum ATCC 824 was synthesized and transformed into Escherichia coli. The previous-ly uncharacterized protein was expressed with a C-terminal His-tag and purified by nickel-nitrilotriacetic acid affinity chromatography. Crystallization and x-ray diffraction to 2.2-A resolution revealed a TIM barrel-like structure with additional Greek key and beta-sandwich folds, similar to other GH44 crystal structures. The enzyme hydrolyzes cellotetraose and larger cellooligosaccharides, yielding an unbalanced product distribution including some...
Source: Applied and Environmental Microbiology - November 13, 2009 Category: Microbiology Authors: Warner CD, Hoy JA, Shilling TC, Linnen MJ, Ginder ND, Ford CF, Honzatko RB, Reilly PJ Tags: Appl Environ Microbiol Source Type: journals
Water and air-distributed conidia differ in sterol content and cytoplasmic microviscosity.Email this article to a colleague.
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Airborne- and waterborne fungal spores were compared with respect to cytoplasmic viscosity and ergosterol presence. These parameters differed markedly among both spore types and correlated to spore survival. This suggests that the mode of spore-dispersal has a bearing on cellular composition, which is relevant for the eradication of industrial relevant fungal propagules.
PMID: 19897752 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Van Leeuwen MR, Van Doorn TM, Golovina EA, Stark J, Dijksterhuis J Tags: Appl Environ Microbiol Source Type: journals
Sub-lethal concentrations of common disinfectants influence virulence gene expression in Listeria monocytogenes.Email this article to a colleague.
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Listeria monocytogenes is a food-borne human pathogen that causes listeriosis, a relative rare infection with a high fatality rate. The regulation of virulence gene expression is influenced by several environmental factors, and the aim of the present study was to determine how disinfectants, used routinely in the food industry, affect the expression of different virulence genes in L. monocytogenes when added in sub-lethal concentrations. An agar-based assay was developed to screen the effect of disinfectants on virulence gene promoter expression and was validated at the transcriptional level by Northern blot analysis. ...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Kastbjerg VG, Larsen MH, Gram L, Ingmer H Tags: Appl Environ Microbiol Source Type: journals
Isolation of Prasinoviruses of the green unicellular algae Ostreococcus spp. at a worldwide geographical scale.Email this article to a colleague.
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Ostreococcus spp. are extremely small unicellular eukaryotic green algae found worldwide in marine environments, and they are susceptible to attacks by a diverse group of large DNA viruses. Several biologically distinct species of Ostreococcus are known and differ in the ecological niches that they occupy: while O. tauri (representing clade C strains) is found in marine lagoons and coastal seas, strains belonging to clade A, exemplified by O. lucimarinus, are present in different oceans. We used laboratory cultures of clonal isolates of these two species to assay for the presence of viruses in seawater samples from div...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Bellec L, Grimsley N, Desdevises Y Tags: Appl Environ Microbiol Source Type: journals
Galleria mellonella as model system to study Listeria pathogenesis.Email this article to a colleague.
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Essential aspects of the innate immune response to microbial infection are conserved between insects and mammals. This has generated interest in using insects as model organisms to study host-microbe interactions. We used the greater wax moth Galleria mellonella, which can be reared at 37 degrees C, as a model host for examining virulence potential of Listeria spp.. Here we report that Galleria is an excellent surrogate model of listerial septic infection, capable of clearly distinguishing between pathogenic and non-pathogenic Listeria and even between virulent and attenuated Listeria monocytogenes strains. Virulence r...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Mukherjee K, Altincicek B, Hain T, Domann E, Vilcinskas A, Chakraborty T Tags: Appl Environ Microbiol Source Type: journals
The Lactobacillus casei MaeKR two component system is required for L-malic acid utilization through a malic enzyme pathway.Email this article to a colleague.
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Lactobacillus casei can metabolize L-malic acid via malolactic enzyme (MLF) or malic enzyme (ME). Whereas utilization of L-malic acid via MLF does not support growth, the ME pathway enables L. casei to grow on L-malic acid. In this work we have identified in the genomes of L. casei strains BL23 and ATCC 334 a cluster consisting of two diverging operons, maePE and maeKR, encoding a putative malate transporter (maeP), a ME (maeE) and a two-component (TC) system belonging to the citrate family (maeK and maeR). Homologous clusters were identified in Enterococcus faecalis, Streptococcus agalactiae, Streptococcus pyogenes an...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Landete JM, García-Haro L, Blasco A, Manzanares P, Berbegal C, Monedero V, Zúñiga M Tags: Appl Environ Microbiol Source Type: journals
Monitoring the dissemination of the broad host range plasmid pB10 in sediment microcosms by quantitative PCR.Email this article to a colleague.
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In this report we show that quantitative PCR could be used to monitor the dissemination of the broad host range plasmid pB10 in sediment microcosms. This approach lies on the differential measurement of the host and plasmid DNAs used to inoculate the microcosms, using a particular design of quantitative PCR primers/probes where we took advantage of the mosaic aspect of the bacterial genomes to achieve a highly specific quantitative PCR detection system.
PMID: 19897757 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Bonot S, Merlin C Tags: Appl Environ Microbiol Source Type: journals
Evaluation of Oxygen Metabolism in Anaeromyxobacter dehalogenans Strain 2CP-C Reveals Unique Ecophysiology Among U(VI)-Reducing Bacteria.Email this article to a colleague.
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Anaeromyxobacter spp. respire soluble hexavalent uranium, U(VI), leading to the formation of insoluble U(IV), and are present at the uranium-contaminated Oak Ridge Integrated Field Research Challenge (IFC) site. Pilot-scale in situ bioreduction of U(VI) has been accomplished in Area 3 of the Oak Ridge IFC site following biostimulation, but the susceptibility of the reduced material to oxidants (i.e., oxygen) compromises long-term U immobilization. Following oxygen intrusion, attached A. dehalogenans cells increased approximately five-fold from 2.2 x 10(7) +/- 8.6 x 10(6) to 1.0 x 10(8) +/- 2.2 x 10(7) cells per g of se...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Thomas SH, Sanford RA, Amos BK, Leigh MB, Cardenas E, Löffler FE Tags: Appl Environ Microbiol Source Type: journals
Ecological divergence of the fungal pathogen Didymella rabiei on sympatric wild and domesticated chickpea.Email this article to a colleague.
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For millennia, chickpea (Cicer arietinum) has been grown in the Levant sympatrically with wild Cicer species. Chickpea is traditionally spring-sown while its wild relatives germinate in the autumn and develop in the winter. It has been hypothesized that the human-directed shift of domesticated chickpea to summer production was an attempt to escape the devastating Ascochyta disease caused by Didymella rabiei. We estimated genetic divergence between D. rabiei isolates sampled from wild C. judaicum and domesticated C. arietinum and the potential role of temperature adaptation in this divergence. Neutral genetic markers sh...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Frenkel O, Peever TL, Chilvers MI, Ozkilinc H, Can C, Abbo S, Shtienberg D, Sherman A Tags: Appl Environ Microbiol Source Type: journals
The morphological response of halophilic fungal genus Wallemia to high salinity.Email this article to a colleague.
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The basidiomycetous genus Wallemia is an active inhabitant of hypersaline environments, and it has recently been described as comprising three halophilic and xerophilic species: Wallemia ichthyophaga, Wallemia muriae and Wallemia sebi. Considering the important protective role the fungal cell wall has under fluctuating physico-chemical environments, this study was focused on cell morphology changes, with particular emphasis on the structure of the cell wall, when these fungi were grown in media with low and high salinities. We compared the influence of salinity on the morphological characteristics of Wallemia spp. by l...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Kralj Kuncic M, Kogej T, Drobne D, Gunde-Cimerman N Tags: Appl Environ Microbiol Source Type: journals
Metabolic engineering of fungal strains for the conversion of D-galacturonate to meso-galactarate.Email this article to a colleague.
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D-Galacturonic acid can be obtained by hydrolysing pectin, which is an abundant and low value raw material. By means of metabolic engineering we constructed fungal strains for the conversion of D-galacturonate to meso-galactarate (mucate). Galactarate has applications in food, cosmetics and pharmaceuticals, and as a platform chemical. In fungi D-galacturonate is catabolised through a reductive pathway with a D-galacturonate reductase as the first enzyme. Deleting the corresponding gene in the fungi Hypocrea jecorina and Aspergillus niger resulted in strains unable to grow on D-galacturonate. The genes of the pathway fo...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: Mojzita D, Wiebe M, Hilditch S, Boer H, Penttilä M, Richard P Tags: Appl Environ Microbiol Source Type: journals
Tetralin-induced and ThnR regulated aldehyde dehydrogenase and {beta}-oxidation genes in Sphingomonas macrogolitabida strain TFA.Email this article to a colleague.
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A new cluster of genes has been found downstream of the previously identified thnA2 gene. The gene products are similar to non-acylating aldehyde dehydrogenases (ThnG) and to proteins representing a complete beta-oxidation pathway (ThnH to ThnP). ThnG has a non-acylating NAD-dependent pimelic semialdehyde dehydrogenase activity that renders pimelic acid a 7-carbon dicarboxylic acid. For further metabolism via beta-oxidation, pimelic acid could be acylated by a constitutive acyl-CoA ligase found in TFA or by ThnH, which would transfer coenzyme A from a previously acylated molecule. The first round of beta-oxidation is e...
Source: Applied and Environmental Microbiology - November 6, 2009 Category: Microbiology Authors: López-Sánchez A, Floriano B, Andújar E, Hernáez MJ, Santero E Tags: Appl Environ Microbiol Source Type: journals
CLM1 in Fusarium graminearum encodes a longiborneol synthase that is required for culmorin production.Email this article to a colleague.
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Fusarium graminearum is a fungal pathogen of cereal crops (e.g. wheat, barley, maize) and produces a number of mycotoxins including 15-acetyldeoxynivalenol, butenolide, zearalenone, and culmorin. To identify a biosynthetic gene for the culmorin pathway, an EST database was examined for terpene cyclase genes. A gene designated CLM1 was expressed under trichothecene-inducing conditions. Expression of CLM1 in yeast (Saccharomyces cerevisiae) resulted in the production of a sesquiterpene alcohol, longiborneol, which has the same ring structure as culmorin. Gene disruption and add-back experiments in F. graminearum showed t...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: McCormick SP, Alexander NJ, Harris LJ Tags: Appl Environ Microbiol Source Type: journals
Copper stress induces a global stress response and represses sae and agr expression and biofilm formation in Staphylococcus aureus.Email this article to a colleague.
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In this study we have used DNA microarray to identify S. aureus copper responsive genes. Transcriptional profiling of S. aureus SH1000 grown in excess copper identified a number of genes which fall into four groups suggesting that S. aureus has four main mechanisms for adapting to high levels of environmental copper. (i) Induction of direct copper homeostasis mechanisms, (ii) increased oxidative stress resistance, (iii) expression of the misfolded protein response, and (iv) repression of a number of transporters and global regulators such as Agr and Sae. Our experimental data confirms that resistance to oxidative stress an...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Baker J, Sitthisak S, Sengupta M, Johnson M, Jayaswal RK, Morrissey JA Tags: Appl Environ Microbiol Source Type: journals
Multilocus variable number of tandem repeats analysis and plasmid profiling to study the occurrence of blaCMY-2 within a PFGE-defined clade of Salmonella enterica serovar Typhimurium.Email this article to a colleague.
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The objective of this study was to describe a possible mechanism of acquisition of third generation cephalosporin resistance in this clade. Ceftazidime resistance increased steadily among WA-TYP035/187 isolates from 0% (0/2) in 1999 to77.8% (28/36) in 2006 (chi(2) for linear trend, p-value < 0.001). Among 112 bovine-source and 18 human-source isolates, 49 (43.8%) and 12 (66.7%) were resistant to ceftazidime, respectively. Multiple-locus variable number tandem repeat analysis (MLVA) and plasmid profiling suggested that resistance was acquired by multiple independent genetic events within the WA-TYP035/187 clade. Given th...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Adhikari B, Besser TE, Gay JM, Fox LK, Hancock DD, Davis MA Tags: Appl Environ Microbiol Source Type: journals
Aromatic amino acid auxotrophs constructed by recombinant marker exchange in Methylophilus methylotrophus AS1 cells expressing the aroP encoded transporter of Escherichia coli.Email this article to a colleague.
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We describe a novel method of constructing mutants of the bacterium Methylophilus methylotrophus AS1 that are auxotrophic for aromatic amino acids. The procedure begins with the Mu-driven integration of the Escherichia coli aroP gene, which encodes the common aromatic amino acid transporter, into the genome of M. methylotrophus. The resulting recombinant strain, with improved permeability to certain amino acids and their analogues, was used for mutagenesis. Mutagenesis was carried out by recombinant substitution of the target genes in the chromosome by linear DNA using the FLP-excisable marker flanked with cloned homologou...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Yomantas YA, Tokmakova IL, Gorshkova NV, Abalakina EG, Kazakova SM, Gak ER, Mashko SV Tags: Appl Environ Microbiol Source Type: journals
Maltose improves Glucose Utilization in Corynebacterium glutamicum: Application for the Improvement of L-Valine Productivity.Email this article to a colleague.
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Corynebacterium glutamicum efficiently utilizes maltose as a substrate. We here show that the presence of maltose increases glucose utilization by rising expression of ptsG, encoding the glucose-specific EII of the phosphotransferase system. Consequently, L-valine productivity of a pyruvate dehydrogenase complex-deficient C. glutamicum strain was improved in the presence of maltose.
PMID: 19880641 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Krause FS, Henrich A, Blombach B, Krämer R, Eikmanns BJ, Seibold GM Tags: Appl Environ Microbiol Source Type: journals
Aromatic hydroxylation of indan by the o-xylene-degrading Rhodococcus sp. strain DK17.Email this article to a colleague.
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The metabolically versatile Rhodococcus sp. strain DK17 utilizes indan as a growth substrate via the o-xylene pathway. Metabolite and RT-PCR analyses indicate that o-xylene dioxygenase hydroxylates indan at the 4,5 position of the aromatic moiety to form cis-indan-4,5-dihydrodiol, which is dehydrogenated to 4,5-indandiol by a dehydrogenase. 4,5-indandiol undergoes ring cleavage by a meta-cleavage dioxygenase.
PMID: 19880642 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Kim D, Lee CH, Choi JN, Choi KY, Zylstra GJ, Kim E Tags: Appl Environ Microbiol Source Type: journals
Benthic Bacterial Diversity in Submerged Sinkhole Ecosystems.Email this article to a colleague.
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Physico-chemical characterization, ARISA community profiling, and 16S rRNA gene sequencing approaches were used to study bacterial communities inhabiting submerged Lake Huron sinkholes inundated with hypoxic, sulfate-rich groundwater. Photosynthetic cyanobacterial mats on the sediment surface were dominated by Phormidium autumnale while deeper, organic-rich sediments contained diverse and active bacterial communities.
PMID: 19880643 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Nold SC, Pangborn JB, Zajack HA, Kendall ST, Rediske RR, Biddanda BA Tags: Appl Environ Microbiol Source Type: journals
Interstrain genomic comparison reveals a crucial role for IS elements in the evolution of Lactobacillus helveticus.Email this article to a colleague.
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Lactobacillus helveticus is a versatile diary bacterium found to possess heterogeneous genotypes depending on ecosystem it is being isolated from. The recently published genome sequence showed a remarkable flexibility of its structure, demonstrated by a substantial level of IS element expansion in association with massive gene decay. To assess this diversity and examine the level of genome plasticity within the Lb. helveticus species, an array based comparative genome hybridization (aCGH) experiment was designed in which 10 strains were analysed. The aCGH revealed sixteen clusters of open reading frames (ORFs) flanked ...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Kaleta P, O'Callaghan J, Fitzgerald GF, Beresford TP, Ross RP Tags: Appl Environ Microbiol Source Type: journals
7-Ketocholesterol Catabolism by Rhodococcus jostii RHA1.Email this article to a colleague.
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Oxysterols from steroid autooxidation have numerous harmful effects, but their biodegradation is poorly understood. Microarrays were used to study mineralization of the most common oxysterol, 7-ketocholesterol (7KC), by Rhodococcus jostii RHA1. Growth on 7KC versus cholesterol, resulted in 363 differentially expressed genes, including up-regulation of two large gene clusters putatively encoding steroid catabolism. Despite this difference, 7KC degradation required key genes involved in cholesterol degradation, indicating a common catabolic route.
PMID: 19880645 [PubMed - as supplied by publisher] (Source: Applied an...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Mathieu J, Mohn WW, Eltis LD, Leblanc J, Stewart G, Dresen C, Okamoto K, Alvarez PJ Tags: Appl Environ Microbiol Source Type: journals
Mechanisms of hop inhibition - The transmembrane redox reaction.Email this article to a colleague.
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In this work, a novel mechanistic model of hop inhibition beyond the proton ionophore action towards (beer spoiling) bacteria was developed. Investigations were performed in model systems using cyclic voltammetry for determination of redox processes/conditions in connection with growth challenges with hop sensitive and resistant Lactobacillus (L.) brevis strains in the presence of oxidants. Cyclic voltammetry identified a transmembrane redox reaction of hop compounds at low pH (as common in beer) and in the presence of manganese (present in millimolar levels in lactic acid bacteria). The antibacterial action of hop com...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Behr J, Vogel RF Tags: Appl Environ Microbiol Source Type: journals
"Candidatus Curculioniphilus buchneri", a novel clade of bacterial endocellular symbionts from weevils of the genus Curculio.Email this article to a colleague.
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Here we investigated the bacterial endosymbionts of weevils of the genus Curculio. From all four species of Curculio weevils examined, a novel group of bacterial gene sequences were consistently identified. Molecular phylogenetic analyses demonstrated that the sequences formed a distinct clade in the gamma-Proteobacteria, which was not related to previously known groups of weevil endosymbionts such as Nardonella spp. and Sodalis-allied symbionts. In situ hybridization revealed that the bacterium was intracellularly harbored in a bacteriome associated with larval midgut. In adult females, the bacterium was localized in ...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Toju H, Hosokawa T, Koga R, Nikoh N, Meng XY, Kimura N, Fukatsu T Tags: Appl Environ Microbiol Source Type: journals
Diverse Genetic Markers Concordantly Identify Bovine-origin Escherichia coli O157 Genotypes Under-represented in Human Disease.Email this article to a colleague.
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Genetic markers previously reported to occur at significantly different frequencies in isolates of Escherichia coli O157:H7 obtained from cattle and from clinically affected humans concordantly delineate at least five genetic groups. Isolates in three of these groups consistently carry one or more markers rarely found among clinical isolates.
PMID: 19880648 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Whitworth J, Zhang Y, Bono J, Pleydell E, French N, Besser T Tags: Appl Environ Microbiol Source Type: journals
A low density macro-array targeting non-LEE effectors (nle genes) and main virulence factors of Shiga toxin-encoding Escherichia coli (STEC) as a new approach for the molecular risk assessment of STEC isolates.Email this article to a colleague.
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This study reports on the development of a low density macro-array for simultaneously testing the genes stx1, stx2, eae, ehxA, and six different nle genes issued from genomic islands OI#122 (ent, nleB, nleE) and OI#71 (nleF, nleH1-2, nleA). Various strains of E. coli isolated from the environment, food, animals and healthy children have been compared with clinical isolates of various seropathotypes. The eae gene was detected in all enteropathogenic E. coli (EPEC) strains as well as in enterohaemorrhagic E. coli (EHEC) strains, excepted in EHEC O91:H21 and EHEC O113:H21. The gene ehxA was more prevalent (90%) in EHEC than i...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Bugarel M, Beutin L, Fach P Tags: Appl Environ Microbiol Source Type: journals
Differential Expression of Virulence and Stress Fitness Genes between Clinical and Bovine-biased Genotypes of Escherichia coli O157:H7.Email this article to a colleague.
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Escherichia coli O157:H7 strains can be classified into different genotypes based on the presence of specific Shiga toxin-encoding bacteriophage insertion sites. Certain O157:H7 genotypes predominate among human clinical cases (clinical genotypes), while others are more frequently found in bovines (bovine-biased genotypes). To determine whether inherent differences in gene expression explain the variation in infectivity of these genotypes, we compared the expression patterns of clinical genotype 1 strains with those of bovine-biased genotype 5 strains using microarrays. Important O157:H7 virulence factors including loc...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Kailasan Vanaja S, Springman AC, Besser TE, Whittam TS, Manning SD Tags: Appl Environ Microbiol Source Type: journals
Novel and Diverse tfdA-like Genes Encoding Putative Phenoxyalkanoic Acid Herbicide Degrading Dioxygenases are Abundant in Soil.Email this article to a colleague.
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Phenoxyalkanoic acid (PAA) herbicides are widely used in agriculture. Biotic degradation of such herbicides occurs in soils and is initiated by alpha-ketoglutarate- and Fe(2+)-dependent dioxygenases encoded by tfdA-like genes (i.e., tfdA and tfdAalpha). Novel primers and qPCR assays were developed to analyze the diversity and abundance of tfdA-like genes in soil. Five primer sets targeting tfdA-like genes were designed and evaluated. Primer sets 3-5 specifically amplified tfdA-like genes from soil and a total of 437 sequences were retrieved. Coverages of gene libraries were 62 to 100%, up to 122 genotypes were detected...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Zaprasis A, Liu YJ, Liu SJ, Drake HL, Horn MA Tags: Appl Environ Microbiol Source Type: journals
Examination of Xenorhabdus nematophila lipases in pathogenic and mutualistic host interactions reveals a role for xlpA in nematode progeny production.Email this article to a colleague.
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Xenorhabdus nematophila is a gamma-proteobacterium and broad host-range insect pathogen. It is also a symbiont of Steinernema carpocapsae, the nematode vector that transports the bacterium between insect hosts. X. nematophila produces several secreted enzymes, including hemolysins, lipases, and proteases, which are thought to contribute to virulence or nutrient acquisition for the bacterium and its nematode host in vivo. X. nematophila has two lipase activities with distinct in vitro specificities for Tween and lecithin. The gene encoding the Tween lipase, xlpA, has been identified and is not required for X. nematophil...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Richards GR, Goodrich-Blair H Tags: Appl Environ Microbiol Source Type: journals
In vivo bioluminescence imaging for the study of intestinal colonization by Escherichia coli in mice.Email this article to a colleague.
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Bioluminescence imaging (BLI) is emerging as a powerful tool for real-time monitoring of infections in living animals. However, since luciferases are oxygenases, it has been suggested that the requirement for oxygen may limit the use of BLI in anaerobic environments such as the lumen of the gut. Strains of Escherichia coli harboring the genes for either the bacterial luciferase from Photorhabdus luminescens or the PpyRE-TS and PpyGR-TS firefly luciferase mutants of Photinus pyralis have been engineered and used to monitor intestinal colonization in the streptomycin-treated mouse model. There was excellent correlation b...
Source: Applied and Environmental Microbiology - October 30, 2009 Category: Microbiology Authors: Foucault ML, Thomas L, Goussard S, Branchini BR, Grillot-Courvalin C Tags: Appl Environ Microbiol Source Type: journals
Investigation of food and environmental exposures relating to epidemiology of Campylobacter coli in humans in North West England.Email this article to a colleague.
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DISCUSSION: there is little evidence to suggest that epidemiological differences between human cases of C. coli and C. jejuni are a result of different food or behavioural exposures alone.
PMID: 19854914 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Sopwith W, Birtles A, Matthews M, Fox A, Gee S, James S, Kempster J, Painter M, Edwards-Jones V, Osborn K, Regan M, Syed Q, Bolton E Tags: Appl Environ Microbiol Source Type: journals
Vegetation and soil environment influence the spatial distribution of root-associated fungi in a mature beech-maple forest.Email this article to a colleague.
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Although the diversity of root-associated fungi can be quite high, the effect of plant distribution and soil environment on root-associated fungal communities at fine spatial scales has received little attention. Here, we examine how soil environment and plant distribution affect the occurrence, diversity and community structure of root-associated fungi at local patch scales within a mature forest. We used terminal restriction fragment length polymorphism (TRFLP) and sequence analysis to detect 63 fungal species representing 28 different genera colonizing tree root tips. At least 32 species matched previously identifie...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Burke DJ, López-Gutiérrez JC, Smemo KA, Chan CR Tags: Appl Environ Microbiol Source Type: journals
Presence and Prevalence of Viruses in Local and Migratory Honeybees (Apis mellifera) in Massachusetts.Email this article to a colleague.
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Migratory and local bees in Massachusetts were analyzed for seven viruses; three were detected: black queen cell virus (BQCV), deformed wing virus (DWV), and sacbrood virus (SBV). DWV was most common, followed closely by BQCV and then by SBV. BQCV and SBV were present at significantly higher rates in the migratory bees assayed, bringing into question the impact that these bees have on the health of local bee populations.
PMID: 19854916 [PubMed - as supplied by publisher] (Source: Applied and Environmental Microbiology)
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Welch A, Drummond F, Tewari S, Averill A, Burand JP Tags: Appl Environ Microbiol Source Type: journals
Genome shuffling of Clostridium diolis DSM 15410 for improved 1,3-propanediol production.Email this article to a colleague.
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Several microorganisms are known for their efficient anaerobic conversion of glycerol to 1,3-propanediol, with Clostridium diolis DSM 15410 as one of the better performers in terms of molar yield and volumetric productivity. However, this is still insufficient to compete with established chemical processes. Previous studies have shown that high concentrations of 1,3-propanediol, glycerol and fermentation side products can limit the productivity of C. diolis DSM 15410. Here we describe the use of genome shuffling of the strict anaerobe C. diolis DSM 15410 for improved 1,3-propanediol fermentation. Using chemical mutagen...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Otte B, Grunwaldt E, Mahmoud O, Jennewein S Tags: Appl Environ Microbiol Source Type: journals
Resistance of Saccharomyces cerevisiae to high furfural concentration is based on NADPH-dependent reduction by at least two oxireductases.Email this article to a colleague.
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Biofuels derived from lignocellulosic biomass hold promises for a sustainable fuel economy, but several problems hamper their economical feasibility. One important problem is the presence of toxic compounds in processed lignocellulosic hydrolysates with furfural as a key toxin. While Saccharomyces cerevisiae has some intrinsic ability to reduce furfural to the less toxic furfuryl alcohol, higher resistance is necessary for process conditions. By comparing an evolved, furfural resistant strain and its parent in micro-aerobic, glucose-limited chemostats at increasing furfural challenge, we elucidate key mechanism and the...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Heer D, Heine D, Sauer U Tags: Appl Environ Microbiol Source Type: journals
Enteric Viruses in Raw Vegetables and Groundwater Used for Irrigation in Korea.Email this article to a colleague.
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In this study, we performed reverse transcription-polymerase chain reaction (RT-PCR) and cell culture-PCR to monitor the occurrence of enteric viruses in groundwater samples and in raw vegetables that were cultivated using that groundwater in Korea. Samples were collected ten times from three farms located in Gyeonggi Province, South Korea. RT-PCR and cell culture-PCR were performed to detect adenoviruses (AdVs), enteroviruses (EVs), noroviruses (NoVs), and rotaviruses, followed by sequence analyses of the detected strains. Of the 29 groundwater samples and the 30 vegetable samples, five (17%) and three (10%) were positive...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Cheong S, Lee C, Song SW, Choi WC, Lee CH, Kim SJ Tags: Appl Environ Microbiol Source Type: journals
Non-Fermentative Thermoalkaliphilic Growth is Restricted to Alkaline Environments.Email this article to a colleague.
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Caldalkalibacillus thermarum strain TA2.A1 grew in pH-controlled batch culture containing a fermentable growth substrate (i.e. sucrose) from pH 7.5 to 10.0 with no significant change in the specific growth rate, suggesting that this bacterium was a facultative alkaliphile. However, when strain TA2.A1 was grown on non-fermentable carbon sources like succinate or malate, no growth was observed until the external pH was > 9.0, suggesting that this bacterium was an obligate alkaliphile. Succinate and sucrose transport by strain TA2.A1 showed a similar pH profile to that of growth on these carbon sources and the molar gr...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: McMillan DG, Keis S, Berney M, Cook GM Tags: Appl Environ Microbiol Source Type: journals
Influence of species specificity and other factors on bacteria associated with Stylophora pistillata in Taiwan.Email this article to a colleague.
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Species of bacteria associated with Stylophora pistillata were determined by analyses of 16S ribosomal genes. Coral samples were taken from two distinct sites at Kenting, in the far south of Taiwan; three coral colonies at each site were tagged and sampled in the winter and summer of 2007. Six hundred 16S rRNA gene clones were selected and sequenced for diversity analysis and community comparison. LIBSHUFF and non parametric multiple dimensional scaling analyses showed variations in the composition of the coral-associated bacteria in the different samples, suggesting that seasonal and geographic factors and variations ...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Hong MJ, Yu YT, Chen CL, Chiang PW, Tang SL Tags: Appl Environ Microbiol Source Type: journals
Beta-Lactam Resistance in Salmonella Isolated from Retail Meats in the United States: National Antimicrobial Resistance Monitoring System (NARMS): 2002-2006.Email this article to a colleague.
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Ampicillin-resistant (AMP(R)) Salmonella (n=344) representing 32 serotypes isolated from retail meats from 2002-2006 were tested for susceptibility to 21 other antimicrobial agents, and screened for the presence of five beta-lactamase gene families (blaCMY, blaTEM, blaSHV, blaOXA, blaCTX-M) and class 1 integrons. Among the AMP(R) isolates, 66.9% were resistant to >/=5 antimicrobials and 4.9% to >/= 10 antimicrobials. Co-resistance to other beta-lactams was noted for amoxicillin/clavulanic acid (55.5%), ceftiofur (50%), cefoxitin (50%), and ceftazidime (24.7%), whereas less than 5% of isolates were resistant to pi...
Source: Applied and Environmental Microbiology - October 23, 2009 Category: Microbiology Authors: Zhao S, Blickenstaff K, Glenn A, Ayers SL, Friedman SL, Abbott JW, McDermott PF Tags: Appl Environ Microbiol Source Type: journals
