Bacillus is a genus of bacteria known for their ability to form spores. These spores are a survival mechanism that allows the bacteria to endure extreme conditions. In unfavorable environments, active bacterial cells transform into spores, which are highly resistant to heat, dryness, chemicals, and other stressful conditions. When conditions become favorable again, these spores can germinate and return to active bacterial cells.

Some Bacillus species such as Bacillus coagulans, Bacillus clausii, and Bacillus subtilis are used as probiotics. Their difference from other probiotic bacteria such as Lactobacillus and Bifidobacterium lies in this spore formation. This characteristic theoretically allows them to survive the acidic conditions in the stomach and then germinate in the intestine. However, both Lactobacillus and Bifidobacterium also show some resistance to stomach acid and can survive the passage through the stomach, with the survival rate depending on the acid resistance of the specific strains.

In our Ventra analyses, we have found that Bacillus species are very rare in the human microbiome, especially in babies. This suggests that these bacteria may not regularly germinate in the human intestine. This contrasts with other probiotic bacteria such as Lactobacillus and especially Bifidobacterium, which are more commonly identified as components of the human microbiome.

The exact role and effectiveness of Bacillus probiotics in human intestinal health remain subjects of further research. While some studies show positive effects, our results suggest that Bacillus species may not play a significant role in the microbiome of certain population groups, especially infants.