Bacillus pumilus is a rod-shaped, aerobic, spore-forming bacterium commonly found in soil. It has one circular chromosome containing around 4000 genes. While generally harmless, it has caused a few cases of food poisoning in humans. B. pumilus plays various environmental roles like promoting plant growth, fixing nitrogen, and inhabiting shrimp guts where it inhibits pathogenic bacteria. It is studied as a model organism due to its genetic amenability. Some strains also have industrial uses like producing enzymes for detergents.