A Human-Derived Putative Probiotic, Ligilactobacillus salivarius MCC0226 with Adhesion, Antipathogenic, and Epithelial Gene-Modulatory Properties

Ligilactobacillus salivarius is a well-recognized probiotic species; however, the mechanisms by which individual strains contribute to gut ecosystem homeostasis and protection of the intestinal epithelial barrier remain poorly understood. This study comprehensively characterized a human-derived L. salivarius MCC0226 using an integrated genomic and functional approach to evaluate its probiotic potential. Whole-genome sequencing identified genes associated with acid and bile tolerance, adhesion, exopolysaccharide biosynthesis, oxidative stress response, bacteriocin production, bile salt hydrolase activity, and amino acid biosynthesis. At the same time, genomic safety analysis confirmed the absence of virulence factors and clinically relevant transferable antimicrobial resistance determinants. MCC0226 exhibited high survival under simulated gastric and intestinal conditions, produced 0.64 g L−1 exopolysaccharides, and showed strong adhesion to HT-29 and Caco-2 intestinal epithelial cells. The strain demonstrated broad-spectrum antimicrobial activity against 13 clinically relevant pathogens, reduced adhesion of Salmonella Typhimurium and Clostridioides difficile on HT-29 cells, co-aggregated with enteric pathogens, and produced hydrogen peroxide. Functional metabolite analysis revealed antioxidant activity, cholesterol assimilation under simulated intestinal and colonic conditions, positive bile salt hydrolase activity, and production of lactic, acetic, and butyric acids during inulin fermentation. Furthermore, MCC0226 significantly modulated the expression of epithelial junction-associated genes in HT-29 cells, including OCLN, CLDN3, CDH1, and CLDN2, while ZO-1 remained essentially unaffected. The combined genomic and in vitro evidence indicates that MCC0226 possesses multiple complementary mechanisms supporting intestinal colonization, microbial modulation, and regulation of epithelial junction-associated gene expression, highlighting its potential as a multifunctional probiotic candidate for functional food and nutraceutical applications.