Identification of Genetic bases of Vibrio fluvialis species-specific

20 Vibrio fluvialis is an important foodborne pathogen that causes diarrheal illness and 21 sometimes extraintestinal infections in humans. In this study, we sequenced the genome 22 of a clinical V. fluvialis strain and determined its phylogenetic relations to other Vibrio 23 species by comparative genomic analysis. We found that the closest relationship was 24 between V. fluvialis and V. furnissii, and then V. cholerae and V. mimicus. Moreover, 25 based on genome comparisons and gene complementation experiments, we revealed 26 genetic mechanisms of the biochemical tests that differentiate V. fluvialis from closely 27 related species. Importantly, we identified a variety of genes encoding potential virulence 28 factors, including multiple hemolysins, transcriptional regulators and environmental 29 survival and adaptation apparatuses, and the type VI secretion system, which is indicative 30 of complex regulatory pathways modulating pathogenesis in this organism. The 31 availability of V. fluvialis genome sequences may promote our understandings of 32 pathogenic mechanisms for this emerging pathogen. 33 34