Bacillus cereus

Electron micrograph of Bacillus cereus

Bacillus cereus is a Gram-positive rod-shaped bacterium commonly found in soil, food, and marine sponges. The specific name, cereus, meaning "waxy" in Latin, refers to the appearance of colonies grown on blood agar. Some strains are harmful to humans and cause foodborne illness due to their spore-forming nature, while other strains can be beneficial as probiotics for animals, and even exhibit mutualism with certain plants. B. cereus bacteria may be aerobes or facultative anaerobes, and like other members of the genus Bacillus, can produce protective endospores. They have a wide range of virulence factors, including phospholipase C, cereulide, sphingomyelinase, metalloproteases, and cytotoxin K, many of which are regulated via quorum sensing. B. cereus strains exhibit flagellar motility.