Preclinical Safety Assessment of Bacillus subtilis BS50 for Probiotic and Food Applications

• Published in: Microorganisms (Basel) Vol. 10; no. 5; p. 1038
• Main Authors: Brutscher, Laura M, Borgmeier, Claudia, Garvey, Sean M, Spears, Jessica L
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 17-05-2022; MDPI
• Subjects: Antibiotic resistance; Antibiotics; Antiinfectives and antibacterials; Bacillus; Bacillus subtilis; Bacillus subtilis BS50; Biosynthesis; Cell culture; Dietary supplements; Drug resistance; Epithelial cells; Epithelium; Gene clusters; Genes; Genetic engineering; Genomes; Health risks; Horizontal cells; Horizontal transfer; Intestinal microflora; Lysates; Maximum likelihood method; Membrane permeability; Metabolites; Microbiota; Permeability; Phylogenetics; Probiotics; Resistance factors; Safety; Secondary metabolites; Toxins; Transfer RNA; Virulence; Virulence factors; United Kingdom > UK; United States > US; Bacillus subtilis BS50; safety; probiotics
• ISSN: 2076-2607; 2076-2607
• DOI: 10.3390/microorganisms10051038

Despite the commercial rise of probiotics containing
spp., it remains important to assess the safety of each strain before clinical testing. Herein, we performed preclinical analyses to address the safety of
BS50. Using in silico analyses, we screened the 4.15 Mbp BS50 genome for genes encoding known
toxins, secondary metabolites, virulence factors, and antibiotic resistance. We also assessed the effects of BS50 lysates on the viability and permeability of cultured human intestinal epithelial cells (Caco-2). We found that the BS50 genome does not encode any known
toxins. The BS50 genome contains several gene clusters involved in the biosynthesis of secondary metabolites, but many of these antimicrobial metabolites (e.g., fengycin) are common to
spp. and may even confer health benefits related to gut microbiota health. BS50 was susceptible to seven of eight commonly prescribed antibiotics, and no antibiotic resistance genes were flanked by the complete mobile genetic elements that could enable a horizontal transfer. In cell culture, BS50 cell lysates did not diminish either Caco-2 viability or monolayer permeability. Altogether, BS50 exhibits a robust preclinical safety profile commensurate with commercial probiotic strains and likely poses no significant health risk to humans.