Vibrionales

Vibrionales is an order of Gram-negative, curved-rod bacteria in the class Gammaproteobacteria. Members are predominantly aquatic and chemoorganotrophic, and are facultatively anaerobic. Most are motile by a single polar flagellum and are oxidase-positive. Many Vibrionales are halotolerant or halophilic and inhabit marine and estuarine environments where they associate with plankton, shells, or marine animals.

The order is currently placed within the family Vibrionaceae, which comprises several genera including Vibrio, Aliivibrio, Photobacterium, and Grimontia. The genus Vibrio contains numerous species of medical, environmental, and biotechnological importance, such as V. cholerae, V. vulnificus, and V. parahaemolyticus. Aliivibrio includes A. fischeri, known for bacterial bioluminescence in symbiosis with marine hosts. Photobacterium is another bioluminescent genus, while Grimontia includes G. hollisae.

Ecology and pathogenicity: Several Vibrionales species are human or animal pathogens. V. cholerae causes cholera; V. vulnificus and V. parahaemolyticus cause seafood-associated gastroenteritis and wound infections. Other Vibrionaceae members are harmless saprophytes or marine symbionts. Bioluminescent species such as A. fischeri and Photobacterium spp. form light-producing symbioses with squids and fish, mediated by quorum-sensing systems.

Clinical and public health relevance: Vibrio species are monitored in seafood and coastal waters. Diagnostics rely on Gram staining, oxidase testing, culture in alkaline saline media, and molecular methods.