Vibrio cholerae O1 El Tor: Identification of a gene cluster required for the rugose colony type, exopolysaccharide production, chlorine resistance, and biofilm formation

The rugose colony variant of Vibrio cholerae O1, biotype El Tor, is shown to produce an exopolysaccharide, EPS ETr , that confers chlorine resistance and biofilm-forming capacity. EPS ETr production requires a chromosomal locus, vps , that contains sequences homologous to carbohydrate biosynthesis genes of other bacterial species. Mutations within this locus yield chlorine-sensitive, smooth colony variants that are biofilm deficient. The biofilm-forming properties of EPS ETr may enable the survival of V. cholerae O1 within environmental aquatic habitats between outbreaks of human disease.