Genomic Characterization and Probiotic Potency of Bacillus sp. DU-106, a Highly Effective Producer of L-Lactic Acid Isolated From Fermented Yogurt

Abstract

<i>Bacillus</i> sp. DU-106, a newly isolated member of <i>Bacillus cereus</i> group, exhibits the predominant ability to produce L-lactic acid. The probiotic potency of test strain revealed its survivability at acidic pH, bile salts and viability in simulated gastric juice <i>in vitro</i>. The acute oral toxicity test indicated its no toxicity to laboratory mice <i>in vivo</i>. We further determined the complete genome of strain DU-106 to understand genetic basis as a potential probiotic. It has a circular chromosome and three plasmids for a total genome 5,758,208 bp in size with a G + C content of 35.10%. Genes associated with lactate synthesis were found in the DU-106 genome. We also annotated various stress-related, bile salt resistance, and adhesion-related domains in this strain, which likely provide support in exerting probiotic action by enabling adhesion to host epithelial cells and survival under gastrointestinal tract. Moreover, strain DU-106 genome lacks the virulence genes encodes cereulide synthetase, enterotoxin FM, and cytotoxin K. These phenotypic and genomic probiotic potencies facilitate its potential candidate as probiotic starter in food industry.