Search results for "vibrio"
showing 10 items of 233 documents
Vibrio agarivorans sp. nov., a novel agarolytic marine bacterium.
2002
It is proposed that the new Vibrio species Vibrio agarivorans accommodates two agarolytic, halophilic, fermentative bacterial strains isolated from Mediterranean sea water. The cells were gram-negative, oxidase-positive, polarly flagellated bacilli that fermented glucose without gas production and that produced no decarboxylases. They used a wide range of compounds as sole carbon and energy sources. The DNA G+C content was 44.8 mol%. Phylogenetic analysis based on complete 16S and 23S rDNA sequences revealed that the strains belong to the gamma-Proteobacteria, and are specifically related to Vibrio species. Their nearest relatives were species of the Vibrio fischeri group, sharing 16S rDNA …
The widespread presence of a family of fish virulence plasmids in Vibrio vulnificus stresses its relevance as a zoonotic pathogen linked to fish farms
2021
Vibrio vulnificus is a pathogen of public health concern that causes either primary septicemia after ingestion of raw shellfish or secondary septicemia after wound exposure to seawater. In consequence, shellfish and seawater are considered its main reservoirs. However, there is one aspect of its biology that is systematically overlooked: its association with fish in its natural environment. This association led in 1975 to the emergence of a zoonotic clade within phylogenetic lineage 2 following successive outbreaks of vibriosis in farmed eels. Although this clade is now worldwide distributed, no new zoonotic clades were subsequently reported. In this work, we have performed phylogenetic, ge…
Presence of a capsule in Vibrio vulnificus biotype 2 and its relationship to virulence for eels
1993
Strains of Vibrio vulnificus biotype 2, isolated from internal organs of diseased European eels as pure cultures of opaque cells, together with some reference strains from Japanese eels, were used in this study. Spontaneous translucent-phase variants were obtained from the corresponding parent strains and compared for a variety of phenotypic traits related to virulence for eels. The rate of colony dissociation from opaque to translucent cells was higher (around 10(-2)) than that observed for translucent to opaque cells (10(-3) to 10(-4)). Electron microscopy with ruthenium red revealed the presence of a capsule of variable thickness on opaque cells, whereas translucent-type colonies had no …
Variability of shell repair in the Manila clam Ruditapes philippinarum affected by the Brown Ring Disease: A microstructural and biochemical study
2011
11 pages; International audience; For more than two decades, the Manila clam Ruditapes philippinarum has been regularly affected by Brown Ring Disease (BRD), an epizootic event caused by the bacterium Vibrio tapetis and characterized by the development of a brown deposit on the inner face of valves. Although BRD infection is often lethal, some clams recover by mineralizing a new repair shell layer, which covers the brown deposit and fully isolates it from living tissues. In order to understand this specific shell repair process, the microstructures of repaired zones were compared to those of shells unaffected by BRD. In addition, the organic matrix associated with unaffected shells and to r…
Biochemical and molecular characterization of three serologically different Vibrio harveyi strains isolated from farmed Dicentrarchus labrax from the…
2022
AbstractVibrio harveyi is recognized as one of the major causes of vibriosis, a disease that threatens the long-term sustainability of aquaculture. Current research shows that the Mediterranean strains of V. harveyi are serologically heterogeneous, though research comparing the traits of different strains is scarce. This study aims to describe the biochemical, physiological and genetic characteristics of three serologically different strains of V. harveyi isolated from farmed European Sea bass (Dicentrarchus labrax) from the Adriatic Sea. A total of 32 morphological and biochemical markers were examined and, the susceptibility to 13 antimicrobials tested, and then compared the results of hi…
Role of iron, capsule, and toxins in the pathogenicity of Vibrio vulnificus biotype 2 for mice
1994
The virulence mechanisms of Vibrio vulnificus biotype 2 have been studied and compared with those of biotype 1 in mice as the experimental animals. Biotype 2 isolates from European eels were as virulent for mice as biotype 1 strains (50% lethal dose, about 10(5) CFU per mouse); a septicemic infection developed in less than 24 h. These strains had several properties in common with biotype 1 organisms including capsule expression, uptake of various iron sources, and production of exoproteins, whose role in mouse virulence has been demonstrated. We also discuss the implication of biotype 2 strains in human infections.
Toxicity of waste gasification bottom ash leachate
2011
Abstract Toxicity of waste gasification bottom ash leachate from landfill lysimeters (112 m3) was studied over three years. The leachate of grate incineration bottom ash from a parallel setup was used as reference material. Three aquatic organisms (bioluminescent bacteria, green algae and water flea) were used to study acute toxicity. In addition, an ethoxyresorufin-O-deethylase (EROD) assay was performed with mouse hepatoma cells to indicate the presence of organic contaminants. Concentrations of 14 elements and 15 PAH compounds were determined to characterise leachate. Gasification ash leachate had a high pH (9.2–12.4) and assays with and without pH adjustment to neutral were used. Gasifi…
Differential interaction of the two cholesterol-dependent, membrane-damaging toxins, streptolysin O and Vibrio cholerae cytolysin, with enantiomeric …
2003
AbstractMembrane cholesterol is essential to the activity of at least two structurally unrelated families of bacterial pore-forming toxins, represented by streptolysin O (SLO) and Vibrio cholerae cytolysin (VCC), respectively. Here, we report that SLO and VCC differ sharply in their interaction with liposome membranes containing enantiomeric cholesterol (ent-cholesterol). VCC had very low activity with ent-cholesterol, which is in line with a stereospecific mode of interaction of this toxin with cholesterol. In contrast, SLO was only slightly less active with ent-cholesterol than with cholesterol, suggesting a rather limited degree of structural specificity in the toxin–cholesterol interact…
The emergence of Vibrio pathogens in Europe : ecology, evolution, and pathogenesis (Paris, 11-12th March 2015)
2015
Global change has caused a worldwide increase in reports of Vibrio-associated diseases with ecosystem-wide impacts on humans and marine animals. In Europe, higher prevalence of human infections followed regional climatic trends with outbreaks occurring during episodes of unusually warm weather. Similar patterns were also observed in Vibrio-associated diseases affecting marine organisms such as fish, bivalves and corals. Basic knowledge is still lacking on the ecology and evolutionary biology of these bacteria as well as on their virulence mechanisms. Current limitations in experimental systems to study infection and the lack of diagnostic tools still prevent a better understanding of Vibrio…
Oligomerization of Vibrio cholerae cytolysin yields a pentameric pore and has a dual specificity for cholesterol and sphingolipids in the target memb…
1999
Vibrio cholerae cytolysin permeabilizes animal cell membranes. Upon binding to the target lipid bilayer, the protein assembles into homo-oligomeric pores of an as yet unknown stoichiometry. Pore formation has been observed with model liposomes consisting of phosphatidylcholine and cholesterol, but the latter were much less susceptible to the cytolysin than were erythrocytes or intestinal epithelial cells. We here show that liposome permeabilization is strongly promoted if cholesterol is combined with sphingolipids, whereby the most pronounced effects are observed with monohexosylceramides and free ceramide. These two lipid species are prevalent in mammalian intestinal brush border membranes…