Characterization and Evaluation of <i>Lactobacillus plantarum</i> LC5.2 Isolated from Thai Native Pigs for its Probiotic Potential in Gut Microbiota Modulation and Immune Enhancement

Probiotic supplementation, particularly with <i>Lactobacillus</i> species, enhances growth performance, maintains gastrointestinal microbial balance, and prevents infections in livestock. This study isolated <i>Lactobacillus</i> strains from the feces of healthy native pigs in southern Thailand and assessed their probiotic properties and safety through both <i>in vitro</i> and <i>in vivo</i> evaluations. Nine <i>Lactobacillus</i> strains showed probiotic potential, with <i>Lactobacillus plantarum</i> LC5.2 demonstrating the best characteristics. This strain tolerated both acid and bile (100% tolerance) and exhibited strong adhesion properties, including high auto-aggregation (69.74%), cell surface hydrophobicity (77.14%), adhesion to Caco-2 cells (9.31%), and biofilm formation. It also exhibited antibacterial activity, inhibiting EHEC, EPEC, and <i>Salmonella</i> Typhimurium through organic acid production. Co-aggregation with these pathogens ranged from 60.83% to 74.09%. Safety evaluations showed no hemolytic activity, susceptibility to antibiotics, and co-existence with other probiotics. In mice, <i>L. plantarum</i> LC5.2 showed no toxicity, with normal food intake, behavior, and weight gain. No abnormalities were found in the small intestine, colon, liver, or spleen. Mice administered the probiotic had significantly higher intestinal IgA levels. Gut microbiome analysis revealed no notable structural alterations but indicated an increase in beneficial bacteria, including <i>Lactobacillus</i>. These results suggest that <i>L. plantarum</i> LC5.2 demonstrates strong probiotic potential, safety, and benefits for gut health, making it a promising candidate for livestock applications.