Environmental Role of Pathogenic Traits in Vibrio cholerae

Vibrio cholerae is a natural inhabitant of aquatic ecosystems. Some strains of V. cholerae can colonize human hosts and cause cholera, a profuse watery diarrhea. The major pathogenicity factors and virulence regulators of V. cholerae are encoded either in mobile genetic elements acquired in the environment (e.g., pathogenicity islands or lysogenic phages) or in the core genome. Several lines of evidence indicate that the emergence of numerous virulence traits of V. cholerae occurred in its natural environment, due to biotic and abiotic pressures. Here, we discuss the connections between the human host and the potential ecological roles of these virulence traits. Elucidating these connections will help us understand the emergence of this organism and other facultative bacterial pathogens.