Vibrio cholerae survival and biofilm formation on shrimp chitin/Supervivencia y formacion de biopeliculas de Vibrio cholerae sobre quitina de camaron/Supervivencia e formacao de biofilmes de Vibrio cholerae sobre quitina de camarao

Vibrio cholerae biofilm formation is a phenomenon that influences the life cycle of this human pathogen and its ecological function in the environment. The present work aimed to evaluate the survival and biofilm formation of V. cholerae of clinical and environmental origins with natural chitin. Bacterial suspensions were inoculated in a medium without nutrients and nutritive broth with chitin obtained from shrimp exoskeleton, incubated at different pH and temperatures. In the survival assays, the isolates retained their capacity to form colonies for 31 days in starvation conditions and exposure to chitin as the only source of carbon and nitrogen. In environmental scanning electron microscopy of both microorganisms, bacterial adhesion to the chitin surface was observed, as well as extracellular matrix and biofilm formation during 4-46h in the presence of nutrients. The environmental isolate at 25h had a biofilm architecture with pillars and channels, while the clinical one showed biofilms in less time, without formation of tridimensional structures. In both isolates, PCR detected the gene vpsR, reported for this bacterium in the formation of biofilm. These results demonstrate that V. cholerae isolated from humans and coastal marine waters are able to survive for prolonged periods in association with organisms having a chitin cover and to form biofilms. This research is a contribution to the understanding of environmental survival strategies of V. cholerae and the possible pathways for transmission to humans.