Probiotic characterization of Bacillus subtilis SM10.1

Abstract

As compared to common probiotics such as lactic acid bacteria, Bacillus species has the advantage of being able to produce spores that withstand extreme conditions and long storage period. One of the Bacillus species that has been reported to have probiotic properties is Bacillus subtilis. However, different bacterial strains of the same species might exhibit completely different abilities. Therefore, the specific properties of individual strains should be well-defined. In this study, Bacillus subtilis SM10.1 were examined in vitro for its probiotic properties such as low pH tolerance, bile salt resistance, antibiotic susceptibility, antimicrobial activity, auto-and co-aggregation, and adhesion ability to epithelial cells. Based on the results, spores of B. subtilis SM10.1 showed more tolerance to low pH than vegetative cells. Nevertheless, the vegetative cells of B. subtilis SM10.1 were resistant to bile salts. B. subtilis SM10.1 exhibited antimicrobial activity and high auto-aggregation ability. Its co-aggregation ability with Escherichia coli and Staphylococcus aureus was also strong. B. subtilis SM10.1 demonstrated adherence ability to the buccal epithelial cell and was only resistance to streptomycin, bacitracin, and clindamycin among twenty-three kinds of antibiotics. The results of this study suggested that B. subtilis SM10.1 has potential as a probiotic strain. However, further investigation is required for the use of B. subtilis SM10.1 in human.