bacillus

(microbiology) Any rod-shaped bacterium.

A genus of bacteria that are gram-positive, aerobic, spore-forming rods. With the exception of B. anthracis and the occasional wound contamination and bovine mastitis caused by B. cereus, the organisms are largely saprophytic and do not cause disease. However, they may invade devitalized tissue. They do have importance in the area of food preservation.

• B. actinoides — streptobacillus moniliformis.
• B. aneurinolyticus, B. thiaminolyticus — are thiaminase-producing bacteria which may proliferate in the rumen and contribute to the cerebral lesions in carbohydrate engorgement and polioencephalomalacia in cattle.
• B. anthracis — characterized by its capacity to form spores when exposed to the air and to survive for long periods in soil and other inert materials. Has a characteristic appearance with McFadyean's stain. Causes anthrax in all species.
• B. brevis — the source of tyrothricin.
• B. cereus — a species causing food poisoning, occasional cases of septicemia and bovine mastitis and abortion.
• B. circulans, B. coagulans, B. stearothermophilus — very heat-resistant bacteria which cause fermentation of cereals in canned meat foods. They cause souring but no gas production so that the can does not bulge. Called also flat sour. B. stearothermophilus spores are used to test efficacy of autoclaves.
• B. larvae — the cause of American foulbrood in honeybees.
• B. licheniformis — reported as a cause of abortion in cattle, sheep and pigs, and also isolated from suppurative lesions of horses and cattle.
• B. piliformis — the previous name of clostridium piliforme, the cause of tyzzer's disease.
• B. polymyxa (B. aerosporus) — strains of this organism are the source of the antibiotic polymyxin.
• B. subtilis — a common saprophytic soil and water form, often occurring as a laboratory contaminant, and rarely, in apparently causal relation to pathological processes, such as conjunctivitis.