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 t o produce an exopolysaccharide, EPSETr, that confers chlorine resistance an d biofilm-forming capacity. EPSETr production requires a chromosomal locus, vps, that contains sequences homologous to carbohydrate biosynthesis genes of other bacterial species, Mutations within this locus yield chlorine-sen sitive, smooth colony variants that are biofilm deficient, The biofilm-form ing properties of EPSETr may enable the survival of V. cholerae O1 within e nvironmental aquatic habitats between outbreaks of human disease.