Vibrio
Vibrio is a genus of Gram-negative bacteria, possessing a curved-rod (comma) shape, several species of which can cause foodborne infection, usually associated with eating undercooked seafood. Being highly salt tolerant and unable to survive in fresh water, Vibrio spp. are commonly found in various salt water environments. Vibrio spp. are facultative anaerobes that test positive for oxidase and do not form spores. All members of the genus are motile. They are able to have polar or lateral flagellum with or without sheaths. Vibrio species typically possess two chromosomes, which is unusual for bacteria. Each chromosome has a distinct and independent origin of replication, and are conserved together over time in the genus. Recent phylogenies have been constructed based on a suite of genes (multilocus sequence analysis). O. F. Müller (1773, 1786) described eight species of the genus Vibrio (included in Infusoria), three of which were spirilliforms. Some of the other species are today assigned to eukaryote taxa, e.g., to the euglenoid Peranema or to the diatom Bacillaria. However, Vibrio Müller, 1773 became regarded as the name of a zoological genus, and the name of the bacterial genus became Vibrio Pacini, 1854. Filippo Pacini isolated micro-organisms he called "vibrions" from cholera patients in 1854, because of their motility. In Latin "vibrio" means "to quiver". The genus Vibrio contains a large number of species. So, variation in the biochemical characteristics are most common in case of the genus Vibrio. Colony, morphological, physiological, and biochemical characteristics of the genus Vibrio are shown in the Table below. Note: Group-1: Vibrio alginolyticus; Group-2: Vibrio natriegens, Vibrio pelagius, Vibrio azureus; + = Positive; – =Negative; V =Variable (+/–) Several species of Vibrio are pathogens. Most disease-causing strains are associated with gastroenteritis, but can also infect open wounds and cause sepsis. They can be carried by numerous marine animals, such as crabs or prawns, and have been known to cause fatal infections in humans after exposure.