Viable but nonculturable vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission

Alam, Munirul ; Sultana, Marzia ; Balakrish Nair, G. ; Siddique, A. K. ; Hasan, Nur A. ; Bradley Sack, R. ; Sack, David A. ; Ahmed, K. U. ; Sadique, A. ; Watanabe, H. ; Grim, Christopher J. ; Huq, A. ; Colwell, Rita R. (2007) Viable but nonculturable vibrio cholerae O1 in biofilms in the aquatic environment and their role in cholera transmission PNAS, 104 (45). pp. 17801-17806. ISSN 0027-8424

Full text not available from this repository.

Official URL:

Related URL:


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 (≈25°C) and 4°C, respectively, when no growth was detectable. Slower biofilm formation and extended culturability were observed for cultures incubated at 4°C, compared with ≈25°C, suggesting biofilm production to be temperature dependent and linked to loss of culturability. Small colonies appearing after incubation in microcosms for 54 and 68 days at 25°C and 4°C, respectively, were wbe positive and ctxA and rstR2 negative, indicating loss of bacteriophage CTXF. The coccoid V. cholerae O1 observed as free cells in microcosms incubated for 495 days could not be cultured, but biofilms in the same microcosms yielded culturable cells. It is concluded that biofilms can act as a reservoir for V. cholerae O1 between epidemics because of its long-term viability in biofilms. In contrast to biofilms produced in Mathbaria pond water, V. cholerae O1 in biofilms present in cholera stools and incubated under identical conditions as the Mathbaria pond water biofilms could not be cultured after 2 months, indicating that those V. cholerae cells freshly discharged into the environment are significantly less robust than cells adapted to environmental conditions.

Item Type:Article
Source:Copyright of this article belongs to National Academy of Sciences.
Keywords:Bangladesh; Bacteriophage CTXΦ; DFA; Multiplex-PCR; ctxA
ID Code:80609
Deposited On:01 Feb 2012 12:53
Last Modified:01 Feb 2012 12:53

Repository Staff Only: item control page