Viable but nonculturable <i>Vibrio cholerae</i> O1 in biofilms in the aquatic environment and their role in cholera transmission

Vibrio cholerae persists in aquatic environments predominantly in a nonculturable state. In this study coccoid, nonculturable V. cholerae O1 in biofilms maintained for 495 days in Mathbaria, Bangladesh, pond water became culturable upon animal passage. Culturability, biofilm formation, and the wbe, ctxA, and rstR2 genes were monitored by culture, direct fluorescent antibody (DFA), and multiplex PCR. DFA counts were not possible after formation of biofilm. Furthermore, wbe, but not ctxA, were amplifiable, even after incubation for 54 and 68 days at room temperature ( approximately 25 degrees C) and 4 degrees C, respectively, when no growth was detectable. Slower biofilm formation and extended culturability were observed for cultures incubated at 4 degrees C, compared with approximately 25 degrees C, suggesting…