Bacillus subtilis bacteria, computer illustration. Bacillus subtilis, also known as grass bacillus or hay bacillus, is a Gram-positive, catalase-positive and rod-shaped bacterium. It is found in soil and the gastrointestinal tract of ruminants and humans. As with other members of the genus Bacillus, it can form an endospore, to survive extreme environmental conditions of temperature and desiccation. It is one of the bacterial champions in secreted enzyme production and used on an industrial scale by biotechnology companies. It is sometimes pathogenic in humans, causing severe eye infections such as anterior uveitis (inflammation of the middle layer of the eye), or iridocyclitis (inflammation of the iris).