Probiogenomic and Functional Profiling of the Novel Human Gut-Derived Probiotic Strain Lactococcus lactis SNU-H10...

Lactococcus lactis is a lactic acid-producing bacterium that is globally recognized as safe and is widely used in the food industry, with certain strains exhibiting probiotic properties. Although most studies on L. lactis have focused on strains isolated from dairy products, bacteria derived from the gastrointestinal tract may possess traits that enhance their survival and colonization in the gut environment. In this study, we investigated the probiotic potential of human gut-derived L. lactis SNU-H10 using probiogenomic and functional profiling. SNU-H10 exhibited tolerance to simulated gastric and intestinal fluids, bile salt exposure, and in vitro gut adhesion potential. Safety evaluation confirmed the absence of hemolysis, bile salt hydrolase activity, supported by the lack of genes associated with these traits. SNU-H10 exhibited multifunctional probiotic traits, including in vitro free radical scavenging activity, enhanced survival rate of Caenorhabditis elegans under oxidative stress, and the ability to synthesize 18 amino acids including branched-chain amino acids (BCAAs). Additionally, probiogenomic analysis revealed that SNU-H10 carried genes related to antioxidant activity (including nrdH, trx, and msrA), the putative production of secondary metabolites (nisin, beta-lactone, and type III polyketide synthase), and the biosynthetic pathways for all three BCAAs. Furthermore, comparative genomic analysis showed that genes related to adhesion (LPxTG-motif protein), nisin biosynthesis, and genes needed for BCAA production were more prevalent in human-derived strains than in those isolated from dairy products. These findings suggest that the human gut-derived L. lactis SNU-H10 is a promising probiotic candidate, exhibiting stress tolerance, gut adhesion potential, and multifunctional probiotic traits.