Bacillus coagulans is a lactic acid-forming bacterial species within the genus Bacillus. The organism was first isolated and described as Bacillus coagulans in 1915 by B.W. Hammer at the Iowa Agricultural Experiment Station as a cause of an outbreak of coagulation in evaporated milk packed by an Iowa condensary. Separately isolated in 1935 and described as Lactobacillus sporogenes in the Fifth edition of Bergey's Manual, it exhibits characteristics typical of both genera Lactobacillus and Bacillus, its taxonomic position between the families Lactobacillaceae and Bacillaceae was often debated. However, in the seventh edition of Bergey’s, it was finally transferred to the genus Bacillus. DNA-based technology was used in distinguishing between the two genera of bacteria which are morphologically similar and possess similar physiological and biochemical characteristics.
B. coagulans is a Gram-positive rod (0.9μm by 3.0μm to 5.0μm in size); catalase positive, spore-forming, motile, a facultative anaerobe. B. coagulans may appear Gram-negative when entering the stationary phase of growth. The optimum temperature for growth is 50 °C; range of temperatures tolerated are 30°C - 55°C. IMViC Tests VP and MR (methyl-red) tests are positive.
Bacillus coagulans has been added by the EFSA to their Qualified Presumption of Safety (QPS) list and has been approved for veterinary purposes as GRAS by the U.S. Food and Drug Administration's Center for Veterinary Medicine, as well as by the European Union and is listed by AAFCO for use as a direct fed microbial in livestock production. It is often used in veterinary applications, especially as a probiotic in pigs, cattle, poultry and shrimp. There are many references to use of this bacterium in humans, especially in improving the vaginal flora, improving abdominal pain and bloating in Irritable Bowel Syndrome patients and increasing immune response to viral challenges. One strain of this bacterium has also been assessed for safety as a food ingredient. Spores are activated in the acidic environment of the stomach and begin germinating and proliferating in the intestine.
Bacillus coagulans is often marketed as Lactobacillus sporogenes or a 'sporeforming lactic acid bacterium' probiotic, but this is an outdated name due to taxonomic changes in 1939. Although Bacillus coagulans does produce L+lactic acid, the bacterium used in these products is not a lactic acid bacterium, as Bacillus species do not belong to the lactic acid bacteria. By definition, lactic acid bacteria (Lactobacillus, Bifidobacterium) do not form spores. Therefore, using the name Lactobacillus sporogenes is scientifically incorrect.