Habitat[edit]
This species is commonly found in the upper layers of the soil, and evidence exists that B. subtilis is a normal gut commensal in humans. A 2009 study compared the density of spores found in soil (about 106 spores per gram) to that found in human feces (about 104 spores per gram). The number of spores found in the human gut was too high to be attributed solely to consumption through food contamination.[8]