Search results for "MESH : Bacteria"
showing 9 items of 9 documents
Consequences of organ choice in describing bacterial pathogen assemblages in a rodent population
2017
SUMMARYHigh-throughput sequencing technologies now allow for rapid cost-effective surveys of multiple pathogens in many host species including rodents, but it is currently unclear if the organ chosen for screening influences the number and identity of bacteria detected. We used 16S rRNA amplicon sequencing to identify bacterial pathogens in the heart, liver, lungs, kidneys and spleen of 13 water voles (Arvicola terrestris) collected in Franche-Comté, France. We asked if bacterial pathogen assemblages within organs are similar and if all five organs are necessary to detect all of the bacteria present in an individual animal. We identified 24 bacteria representing 17 genera; average bacterial…
Listeria monocytogenes EGD-e biofilms: no mushrooms but a network of knitted chains.
2008
ABSTRACT Listeria monocytogenes is a food pathogen that can attach on most of the surfaces encountered in the food industry. Biofilms are three-dimensional microbial structures that facilitate the persistence of pathogens on surfaces, their resistance toward antimicrobials, and the final contamination of processed goods. So far, little is known about the structural dynamics of L. monocytogenes biofilm formation and its regulation. The aims of this study were, by combining genetics and time-lapse laser-scanning confocal microscopy (LSCM), (i) to characterize the structural dynamics of L. monocytogenes EGD-e sessile growth in two nutritional environments (with or without a nutrient flow), and…
Agr system of Listeria monocytogenes EGD-e: role in adherence and differential expression pattern.
2007
ABSTRACT In this study, we investigated the agrBDCA operon in the pathogenic bacterium Listeria monocytogenes EGD-e. In-frame deletion of agrA and agrD resulted in an altered adherence and biofilm formation on abiotic surfaces, suggesting the involvement of the agr system of L. monocytogenes during the early stages of biofilm formation. Real-time PCR experiments indicated that the transcript levels of agrBDCA depended on the stage of biofilm development, since the levels were lower after the initial attachment period than during biofilm growth, whereas transcription during planktonic growth was not growth phase dependent. The mRNA quantification data also suggested that the agr system was a…
Virulent synergistic effect between Enterococcus faecalis and Escherichia coli assayed by using the Caenorhabditis elegans model.
2008
5 pages; International audience; BACKGROUND: The role of enterococci in the pathogenesis of polymicrobial infections is still debated. The purpose of this study was to evaluate the effect of virulent enterococci in the presence or absence of Escherichia coli strains in the in vivo Caenorhabditis elegans model. PRINCIPAL FINDINGS: This study demonstrated that there was a synergistic effect on virulence when an association of enterococci and E. coli (LT50 = 1.6 days+/-0.1 according to the tested strains and death of nematodes in 4 days+/-0.5) was tested in comparison with enterococci alone (LT50 = 4.6 days+/-0.1 and death in 10.4 days+/-0.6) or E. coli alone (LT50 = 2.1+/-0.9 and deaths 6.6+/…
Early mitochondrial dysfunction, superoxide anion production, and DNA degradation are associated with non-apoptotic death of human airway epithelial …
2002
It has been shown that bacterial exoproducts may induce airway epithelium injury. During the epithelial repair process, the respiratory epithelial cells no more establish tight junctional intercellular complexes and may be particularly susceptible to bacterial virulence factors. In this study, we analyzed the effect of Pseudomonas aeruginosa exotoxin A (ETA) at different periods of time and concentrations on 16 HBE 14o(-) human bronchial epithelial cells in culture conditions inducing a phenotype of repairing cells. ETA treatment for 24 and 48 h led to the killing of 40.0 +/- 5.7% and 79.0 +/- 1.4% of the cells, respectively, as determined by the dimethylthiazole 2,5 diphenyl tetrazolium br…
Dynamics and identification of soil microbial populations actively assimilating carbon from 13C-labelled wheat residue as estimated by DNA- and RNA-S…
2007
International audience; This work is the first report on the use of DNA-, RNA-SIP approaches to elucidate the dynamics and the diversity of bacterial populations actively assimilating C derived from plant residues labelled at more than 90% (13)C. Wheat-residues, were incorporated and incubated into soil microcosms for 28 days. At the end of the incubation time, no more than 55% of the total CO(2) released was (13)C-labelled, suggesting the occurrence of an important priming effect process. After 7 days, more than 30% of the whole DNA extracted were labelled, allowing an efficient separation of labelled from unlabelled DNA using density gradient centrifugation. The genetic structure of bacte…
Interactions in dual species biofilms between Listeria monocytogenes EGD-e and several strains of Staphylococcus aureus.
2008
International audience; Six environmental isolates of Staphylococcus aureus and one collection strain were investigated for their ability to form monospecies biofilms and dual species biofilms with Listeria monocytogenes EGD-e on stainless steel coupons. All isolates were able to grow as biofilms but their ability to form monospecies biofilms differed. The population of L. monocytogenes EGD-e in dual species biofilms was not affected by the presence of S. aureus isolates except for strain CIP 53.156. The effect of L. monocytogenes EGD-e on the population of S. aureus was strain dependent: S. aureus population either increased or decreased or was not affected in the presence of L. monocytoge…
Acyl-homoserine lactone production is more common among plant-associated Pseudomonas spp. than among soilborne Pseudomonas spp.
2001
ABSTRACT A total of 137 soilborne and plant-associated bacterial strains belonging to different Pseudomonas species were tested for their ability to synthesize N -acyl-homoserine lactones (NAHL). Fifty-four strains synthesized NAHL. Interestingly, NAHL production appears to be more common among plant-associated than among soilborne Pseudomonas spp. Indeed, 40% of the analyzed Pseudomonas syringae strains produced NAHL which were identified most often as the short-chain NAHL, N -hexanoyl- l -homoserine lactone, N -(3-oxo-hexanoyl)-homoserine lactone, and N -(3-oxo-octanoyl)- l -homoserine lactone (no absolute correlation between genomospecies of P. syringae and their ability to produce NAHL …
Immunoaffinity purification and characterization of mitochondrial membrane-bound D-3-hydroxybutyrate dehydrogenase from Jaculus orientalis.
2008
Abstract Background The interconversion of two important energy metabolites, 3-hydroxybutyrate and acetoacetate (the major ketone bodies), is catalyzed by D-3-hydroxybutyrate dehydrogenase (BDH1: EC 1.1.1.30), a NAD+-dependent enzyme. The eukaryotic enzyme is bound to the mitochondrial inner membrane and harbors a unique lecithin-dependent activity. Here, we report an advanced purification method of the mammalian BDH applied to the liver enzyme from jerboa (Jaculus orientalis), a hibernating rodent adapted to extreme diet and environmental conditions. Results Purifying BDH from jerboa liver overcomes its low specific activity in mitochondria for further biochemical characterization of the e…