Brevibacillus brevis (formerly known as Bacillus brevis^[2]) is a Gram-positive, aerobic, motile, spore-forming, rod-shaped bacterium commonly found in soil, air, water, and decaying matter. It is rarely associated with infectious diseases.^[3] The antibiotics gramicidin and tyrocidine were first isolated from it.^[4]

Brevibacillus brevis is catalase positive, amylase negative, casein negative, gelatinase positive, and indole negative; most strains are citrate users. Some strains are capable of oxidizing carbon monoxide aerobically. Optimal growth occurs at 35 °C to 55 °C.