Butyrivibrio

Butyrivibrio is a genus of bacteria in Class Clostridia. Bacteria of this genus are common in the gastrointestinal systems of many animals. Genus Butyrivibrio was first described by Bryant and Small (1956) as anaerobic, butyric acid-producing, curved rods (or vibroids). Butyrivibrio cells are small, typically 0.4 – 0.6 μm by 2 – 5 μm. They are motile, using a single polar or subpolar monotrichous flagellum. They are commonly found singly or in short chains but it is not unusual for them to form long chains. Despite historically being described as Gram-negative, their cell walls contain derivatives of teichoic acid, and electron microscopy indicates that bacteria of this genus have a Gram-positive cell wall type. It is thought that they appear Gram-negative when Gram stained because their cell walls thin to 12 to 18 nm as they reach stationary phase.

Butyrivibrio species are common in the rumens of ruminant animals such as cows, deer and sheep, where they are involved in a number of ruminal functions of agricultural importance in addition to butyrate production. These include fibre degradation, protein breakdown, biohydrogenation of lipids and the production of microbial inhibitors. Of particular importance to ruminant digestion, and therefore productivity, is their contribution to the degradation of plant structural carbohydrates, principally hemicellulose.