Vibrio

Vib' ri.o . L. v. vibrio move rapidly back and forth, vibrate; M.L. masc. n. Vibrio the vibrating, darting organism. Proteobacteria / Gammaproteobacteria / “Vibrionales” / Vibrionaceae / Vibrio Small, straight, slightly curved, curved, or comma‐shaped rods , 0.5–0.8 × 1.4–2.6 µm. Involution forms often occur in old cultures and are formed under adverse growth conditions. Do not form endospores or microcysts. Gram negative. In liquid media, motile by monotrichous or multitrichous polar flagella enclosed in a sheath continuous with the outer membrane of the cell wall. On solid media, some species synthesize numerous lateral flagella with a wavelength shorter than that of the sheathed polar flagellum. Facultative anaerobes capable of both fermentative and respiratory metabolism . Molecular oxygen is a universal electron acceptor. Most do not denitrify or fix molecular nitrogen. All are chemoorganotrophs; most are able to grow in a mineral medium containing D ‐glucose as the sole carbon source and NH + as the sole nitrogen source . A few strains have organic growth factor requirements. Na 4 + stimulates growth of all species and is an absolute requirement for most ; the minimal concentration necessary for optimal growth ranges from 5 to 700 mM (0.029–4.1%). Most species grow well in media containing a seawater base. All ferment D ‐glucose producing acid but rarely gas ; several species produce acetoin and acetyl methyl carbinol ( positive Voges–Proskauer test ). Most ferment and utilize D ‐fructose, maltose, and glycerol; are oxidase positive and reduce nitrate to nitrite . Several grow at 4°C; all grow at 20°C; most grow at 30°C; many grow at 35–37°C. A few species are bioluminescent , as are a few strains of normally nonluminescent species. Primarily aquatic ; species distribution is usually dependent on Na + and nutrient content of the water as well as its temperature. Very common in marine and estuarine environments and on the surfaces and in the intestinal contents of marine animals. Species with a low Na + requirement are also found in freshwater habitats. Twelve species occur in human clinical specimens; 11 of these are apparently pathogenic for humans, causing diarrhea or extraintestinal infections. Several species cause diseases of other vertebrates and invertebrates . The mol % G + C of the DNA is : 38–51. Type species : Vibrio cholerae Pacini 1854, 411.