Bacillus spp are aerobic spore forming rods that stain gram positive or gram variable. Except for few species the large majority have no pathogenic potential and have never been associated with disease in man or animals. Members of the genus have significant microbiological uses . Numerous enzymes, antibiotics and other metabolites have medical, agricultural, pharmaceutical and other industrial applications. Examples of antibiotics formed by Bacillus spp include bacitracin by B. licheniformis or B. subtilis, polymyxin by B. polymyxa and gramicidin by B. brevis. Certain strains of Bacillus have been utilized as biological controls in antibiotics and other assays.
Some types of Bacillus bacteria are harmful to humans, plants, or other organisms. For example, B. cereus sometimes causes spoilage in canned foods and food poisoning of short duration. B. subtilis is a common contaminant of laboratory cultures and is often found on human skin. Most strains of Bacillus are not pathogenic for humans but may, as soil organisms, infect humans incidentally. A notable exception is B. anthracis, which causes anthrax in humans and domestic animals. B. thuringiensis produces a toxin (Bt toxin) that causes disease in insects.