Bacillus is a genus of Gram-positive, rod-shaped (bacillus), bacteria and a member of the phylum Firmicutes. Bacillus species can be obligate aerobes (oxygen reliant), or facultative anaerobes (having the ability to be aerobic or anaerobic). They will test positive for the enzyme catalase when there has been oxygen used or present.[2] Ubiquitous in nature, Bacillus includes both free-living (non-parasitic) and parasitic pathogenic species. Under stressful environmental conditions, the bacteria can produce oval endospores that are not true spores but which the bacteria can reduce themselves to and remain in a dormant state for very long periods. These characteristics originally defined the genus, but not all such species are closely related, and many have been moved to other genera of Firmicutes.[3]
Many species of Bacillus can produce copious amounts of enzymes which are made use of in different industries. Some Bacillus species can form intracellular inclusions of polyhydroxyalkanoates under certain adverse environmental conditions, as in a lack of elements such as phosphorus, nitrogen, or oxygen combined with an excessive supply of carbon sources.
B.subtilis has proved a valuable model for research. Other species of Bacillus are important pathogens, causing anthrax and food poisoning.