Search results for "BACTERIA"
showing 10 items of 4919 documents
Oil-degrading bacteria from a membrane bioreactor (BF-MBR) system for treatment of saline oily waste: Isolation, identification and characterization …
2016
A collection of forty-two (42) strains was obtained during microbiological screening of a Membrane Bioreactor (MBR) system developed for the treatment of saline oily waste originated from marine transportation. The diversity of the bacterial collection was analyzed by amplification and sequencing of the 16S rRNA gene. Taxonomic analysis showed high level of identity with recognized sequences of seven (7) distinct bacterial genera (Alcanivorax, Erythrobacter, Marinobacter, Microbacterium, Muricauda, Rhodococcus and Rheinheimera). The biotechnological potential of the isolates was screened considering an important factor such as the biosurfactant production. In particular fourteen (14) biosur…
Constitutive activation of MexT by amino acid substitutions results in MexEF-OprN overproduction in clinical isolates of Pseudomonas aeruginosa
2018
ABSTRACT When overproduced, the multidrug efflux system MexEF-OprN increases the resistance of Pseudomonas aeruginosa to fluoroquinolones, chloramphenicol, and trimethoprim. In this work, we demonstrate that gain-of-function mutations in the regulatory gene mexT result in oligomerization of the LysR regulator MexT, constitutive upregulation of the efflux pump, and increased resistance in clinical isolates.
Different food sources elicit fast changes to bacterial virulence
2016
Environmentally transmitted, opportunistic bacterial pathogens have a life cycle that alternates between hosts and environmental reservoirs. Resources are often scarce and fluctuating in the outside-host environment, whereas overcoming the host immune system could allow pathogens to establish a new, resource abundant and stable niche within the host. We tested if short-term exposure to different outside-host resource types and concentrations affect Serratia marcescens —(bacterium)'s virulence in Galleria mellonella (moth). As expected, virulence was mostly dictated by the bacterial dose, but we also found a clear increase in virulence when the bacterium had inhabited a low (versus high) re…
Chromosome-Encoded Hemolysin, Phospholipase, and Collagenase in Plasmidless Isolates of Photobacterium damselae subsp. damselae Contribute to Virulen…
2017
ABSTRACT Photobacterium damselae subsp. damselae is a pathogen of marine animals, including fish of importance in aquaculture. The virulence plasmid pPHDD1, characteristic of highly hemolytic isolates, encodes the hemolysins damselysin (Dly) and phobalysin (PhlyP). Strains lacking pPHDD1 constitute the vast majority of the isolates from fish outbreaks, but genetic studies to identify virulence factors in plasmidless strains are scarce. Here, we show that the chromosome I-encoded hemolysin PhlyC plays roles in virulence and cell toxicity in pPHDD1-negative isolates of this pathogen. By combining the analyses of whole genomes and of gene deletion mutants, we identified two hitherto uncharacte…
Characteristic of Pseudomonas syringae pv. atrofaciens Isolated from Weeds of Wheat Field
2021
The aim of this study was the identification of the causative agent of the basal glume rot of wheat Pseudomonas syringae pv. atrofaciens from the affected weeds in wheat crops, and determination of its virulent properties. Isolation of P. syringae pv. atrofaciens from weeds of wheat crops was carried out by classical microbiological methods. To identify isolated bacteria, their morphological, cultural, biochemical, and serological properties as well as fatty acids and Random Amplification of Polymorphic DNA (RAPD)-PCR (Polymerase chain reaction) profiles with the OPA-13 primer were studied. Pathogenic properties were investigated by artificial inoculation of wheat plants and weed plants, fr…
Environmental radiation alters the gut microbiome of the bank vole Myodes glareolus.
2018
International audience; Gut microbiota composition depends on many factors, although the impact of environmental pollution is largely unknown. We used amplicon sequencing of bacterial 16S rRNA genes to quantify whether anthropogenic radionuclides at Chernobyl (Ukraine) impact the gut microbiome of the bank vole Myodes glareolus. Exposure to elevated levels of environmental radionuclides had no detectable effect on the gut community richness but was associated with an almost twofold increase in the Firmicutes:Bacteroidetes ratio. Animals inhabiting uncontaminated areas had remarkably similar gut communities irrespective of their proximity to the nuclear power plant. Hence, samples could be c…
Successful aerobic bioremediation of groundwater contaminated with higher chlorinated phenols by indigenous degrader bacteria
2018
The xenobiotic priority pollutant pentachlorophenol has been used as a timber preservative in a polychlorophenol bulk synthesis product containing also tetrachlorophenol and trichlorophenol. Highly soluble chlorophenol salts have leaked into groundwater, causing severe contamination of large aquifers. Natural attenuation of higher-chlorinated phenols (HCPs: pentachlorophenol + tetrachlorophenol) at historically polluted sites has been inefficient, but a 4-year full scale in situ biostimulation of a chlorophenol-contaminated aquifer by circulation and re-infiltration of aerated groundwater was remarkably successful: pentachlorophenol decreased from 400 μg L−1 to <1 μg L−1 and tetrachlorophen…
Lepidopteran species have a variety of defence strategies against bacterial infections
2017
The insect immune system has versatile ways of coping with microbial insults. Currently, innate immune priming has been described in several invertebrates, and the first insights into its mechanistic basis have been described. Here we studied infections with two different strains of Serratia marcescens bacteria in two different Lepidopteran hosts. The results reveal fundamental differences between the two hosts, a well-known model organism Galleria mellonella and a non-model species Arctia plantaginis. They differ in their strategies for resisting oral infections; priming their defences against a recurring sepsis; and upregulating immunity related genes as a response to the specific pathoge…
Ceftolozane-Tazobactam Combination Therapy Compared to Ceftolozane-Tazobactam Monotherapy for the Treatment of Severe Infections: A Systematic Review…
2021
Ceftolozane-tazobactam (C/T) is a combination of an advanced-generation cephalosporin (ceftolozane) with a &beta
Effect of resource availability on evolution of virulence and competition in an environmentally transmitted pathogen
2018
Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we devel…