ABSTRACT
Vibrios are short curved or straight cells, which are single or united into spirals. They grow well and rapidly on the surfaces of standard culture media and can be readily isolated from estuarine, marine, and fresh-water samples. These heterotrophic organisms vary in their nutritional requirements; some occur as parasites and pathogens for animals and for humans. The short curved, asporogenous, Gram-negative rods that are members of the genus Vibrio are most commonly encountered in the estuarine, marine, or fresh-water habitat. Distinguishing species of the genus Vibrio from other related genera can be presumptively accomplished by examining Gram stains of carefully prepared specimens, followed by electron microscopy to confirm morphology. Vibrio species are short rods with a curved axis, motile by means of a single polar flagellum. Vibrio species may be short, straight rods (1.5–3.0 μm × 0.5 μm), or they may be S-shaped or spiral-shaped when individual cells are joined. Possession of two or more flagella in a polar tuft has also been demonstrated in Vibrio species, as have lateral flagella in Vibrio parahaemolyticus. Thus, to identify and classify vibrios, physiological and biochemical taxonomic tests are done. 1 Vibrio species are facultatively anaerobic, with both a respiratory (oxygen-utilizing) and a fermentative metabolism. Related genera may be aerobic or microaerophilic, with a strictly respiratory metabolism (oxygen is the terminal electron acceptor).
