Phenotypic characterization and genome analysis reveal the probiotic potential of a banyan endophyte Bacillus velezensis K1.

AIM

The current study aimed to scrutinize the probiotic traits and safety aspects of Bacillus velezensis K1 through experimental and supporting genome studies.

METHODS AND RESULTS

The seven cultures previously isolated from the aerial roots of Ficus benghalensis were initially screened for their antibacterial activity as well as acid and bile tolerance. The isolate K1 was found to be the most potent and was further investigated for probiotic traits and safety. K1 showed tolerance to simulated digestive juices and 0.3% bile. It showed notable aggregation, cell surface hydrophobicity, and adherence to HT-29 cells. K1 significantly prevented the adhesion of E. coli O157: H7 and S. enterica ATCC 13076 to HT-29 in cell culture assays. K1 could hydrolyze phytate and complex polysaccharides. The genes related to stress tolerance, adhesion, antimicrobial activity, and production of vitamins, viz. thiamine, riboflavin, pyridoxine, pantothenic acid, folate, and biotin were annotated in the K1 genome. K1 was found to be non-hemolytic, noncytotoxic, as well as susceptible to antibiotics. No virulence or toxin-encoding genes were identified in its genome.

CONCLUSIONS

B. velezensis K1 is a prospective probiotic with the ability to tolerate gastrointestinal stress, adhere to intestinal surfaces, and inhibit enteropathogens.