B. subtilis is only known to cause disease in severely immunocompromised patients, and can conversely be used as a probiotic in healthy individuals.[43] It rarely causes food poisoning.[44] Some B. subtilis strains produce the proteolytic enzyme subtilisin.
B. subtilis spores can survive the extreme heat during cooking. Some B. subtilis strains are responsible for causing ropiness — a sticky, stringy consistency caused by bacterial production of long-chain polysaccharides — in spoiled bread dough. For a long time, bread ropiness was associated uniquely with B. subtilis species by biochemical tests. Molecular assays (randomly amplified polymorphic DNA PCR assay, denaturing gradient gel electrophoresis analysis, and sequencing of the V3 region of 16S ribosomal DNA) revealed greater Bacillus species variety in ropy breads, which all seems to have a positive amylase activity and high heat resistance.[45]
B. subtilis and substances derived from it has been evaluated by different authoritative bodies for their safe and beneficial use in food. In the United States, an opinion letter issued in the early 1960s by the Food and Drug Administration (FDA) recognized some substances derived from microorganisms as Generally recognized as safe (GRAS), including carbohydrase and protease enzymes from B. subtilis. The opinions were predicated on the use of nonpathogenic and nontoxicogenic strains of the respective organisms and on the use of current good manufacturing practices.[46] The FDA stated the enzymes derived from the B. subtilis strain were in common use in food prior to January 1, 1958, and that nontoxigenic and nonpathogenic strains of B. subtilis are widely available and have been safely used in a variety of food applications. This includes consumption of Japanese fermented soy bean, in the form of Natto, which is commonly consumed in Japan, and contains as many as 108 viable cells per gram. The fermented beans are recognized for their contribution to a healthy gut flora and vitamin K2 intake; during this long history of widespread use, natto has not been implicated in adverse events potentially attributable to the presence of B. subtilis.[citation needed] The natto product and the B. subtilis natto as its principal component are FOSHU (Foods for Specified Health Use) approved by the Japanese Ministry of Health, Labour and Welfare as effective for preservation of health.[47]
B. subtilis has been granted "Qualified Presumption of Safety" status by the European Food Safety Authority.[48] B. subtilis is part of the authoritative list of microorganisms with a documented history of safe use in food, established by the International Dairy Federation in collaboration with the European Food and Feed Cultures Association in 2002, and updated in 2012.[citation needed]
