B. coagulans is a Gram-positive rod (0.9 by 3.0 to 5.0 μm in size), catalase positive, spore-forming, motile, and a facultative anaerobe. It may appear Gram-negative when entering the stationary phase of growth. The optimum temperature for growth is 50°C (122°F) ; range of temperatures tolerated are 30-55°C (86-131°F). IMViC tests VP and MR (methyl-red) tests are positive.