Project description:UnlabelledThe genetic heterogeneity of the close relatives Vibrio anguillarum and Vibrio ordalii, both serious pathogens of fish causing extensive losses in aquaculture, was studied. Eight housekeeping genes, i.e., atpA, ftsZ, gapA, gyrB, mreB, rpoA, topA, and pyrH, were partially sequenced in 116 isolates from diverse fish species and geographical areas. The eight genes appear to be under purifying selection, and the genetic diversity in the total data set was estimated to be 0.767 ± 0.026. Our multilocus sequence analysis (MLSA) scheme identified several widespread clonal complexes and resolved the isolates, for the most part, according to serotype. Serotype O2b isolates from diseased cod in Norway, Ireland, and Scotland were found to be extremely homogeneous. Horizontal gene transfer appears to be fairly common within and between clonal complexes. Taken together, MLSA and in silico DNA-DNA hybridization (DDH) calculations suggest that some isolates previously characterized as V ordalii, i.e., 12B09, FF93, FS144, and FS238, are in fact V. anguillarum isolates. The precise taxonomic situation for two isolates from Atlantic cod that display several traits consistent with V. ordalii, i.e., NVI 5286 and NVI 5918, and a single environmental strain that was previously considered to represent V. ordalii, i.e., FF167, is less clear.ImportanceIt is still being debated whether V. anguillarum and V ordalii represent separate bacterial species. Our study addresses this issue and elucidates the degree of genetic variability within this group of closely related bacteria, based on a substantial number of isolates. Our results clearly illustrate the existence of different populations among putative V ordalii isolates. On the basis of additional full-length genomic analysis, we conclude that most environmental isolates previously identified as V ordalii lie firmly within the species V. anguillarum While bona fide fish-pathogenic V ordalii isolates display a very close genetic relationship with V. anguillarum, they combine a clearly divergent evolutionary pattern with clear phenotypic differences. The study also highlights the need for further characterization of fish-pathogenic isolates from the northern Atlantic region that share phenotypic characteristics with V. ordalii but are genetically closer to V. anguillarum The retention of taxonomic distinctions between the phenotypically different groups of bacteria is of practical advantage to microbial ecologists and veterinarians.
Project description:Vibrio ordalii is the causative agent of vibriosis, mainly in salmonid fishes, and its virulence mechanisms are still not completely understood. In previous works we demonstrated that V. ordalii possess several iron uptake mechanisms based on heme utilization and siderophore production. The aim of the present work was to confirm the production and utilization of piscibactin as a siderophore by V. ordalii. Using genetic analysis, identification by peptide mass fingerprinting (PMF) of iron-regulated membrane proteins and chemical identification by LC-HRMS, we were able to clearly demonstrate that V. ordalii produces piscibactin under iron limitation. The synthesis and transport of this siderophore is encoded by a chromosomal gene cluster homologous to another one described in V. anguillarum, which also encodes the synthesis of piscibactin. Using β-galactosidase assays we were able to show that two potential promoters regulated by iron control the transcription of this gene cluster in V. ordalii. Moreover, biosynthetic and transport proteins corresponding to piscibactin synthesis and uptake could be identified in membrane fractions of V. ordalii cells grown under iron limitation. The synthesis of piscibactin was previously reported in other fish pathogens like Photobacterium damselae subsp. piscicida and V. anguillarum, which highlights the importance of this siderophore as a key virulence factor in Vibrionaceae bacteria infecting poikilothermic animals.
Project description:Environmental isolates of Vibrio cholerae from California coastal water compared to reference strain N16961. A genotyping experiment design type classifies an individual or group of individuals on the basis of alleles, haplotypes, SNP's. Keywords: genotyping_design; array CGH
Project description:Vibrio alginolyticus is a Gram-negative marine bacterium. A limited population of the organisms causes acute gastroenteritis in humans. In this study, Vibrio alginolyticus wild type strain EPGS is compared with the mutants of Ser-Thr kinase PpkA and phosphatase PppA, after cultured for 7h, in Luria-Bertani containing medium 3 % NaCl at 30 C. Our goal is to determine the ppkA and pppA regulon.
Project description:Vibrio alginolyticus is a Gram-negative marine bacterium. A limited population of the organisms causes acute gastroenteritis in humans. In this study, Vibrio alginolyticus wild type strain EPGS is compared with the mutants of Ser-Thr kinase PpkA and phosphatase PppA, after cultured for 7h, in Luria-Bertani containing medium 3 % NaCl at 30 C. Our goal is to determine the ppkA and pppA regulon. Three wild type and five mutant Vibrio alginolyticus samples were compared.