Transfer of Cholera Toxin Genes from O1 to Non-O1/O139 Strains by Vibriophages from California Coastal Waters

Aims: Vibrio cholerae is an important bacterial pathogen that causes global cholera epidemic. Although they are commonly found in coastal waters around the world, most environmental isolates do not contain cholera toxin genes. This study investigates vibriophages in southern California coastal waters and their ability to transfer cholera toxin genes.

Methods And Results: Lytic phages infecting V. cholerae were isolated from Newport Bay, California, between May and November, while none was found in winter. Some of the phage isolates can infect multiple environmental V. cholerae strains and El Tor strains. All phages contained double-stranded DNA. Transduction experiments using kanamycin-resistant gene marked CTXPhi demonstrated that some environmental vibriophages can transfer CTXPhi genes from O1 El Tor strain to environmental non-O1/O139 V. cholerae via generalized transduction.

Conclusions: Vibriophages are important components of the natural aquatic ecosystem. They play an important role in influencing the dynamics and evolution of V. cholerae in the environment.

Significance And Impact Of The Study: This study demonstrates the significance of vibriophages in the coastal environment and transduction as one of the mechanisms of pathogenicity evolution among environmental V. cholerae.