Porcine-derived Bacillus subtilis YB-X-721 alleviates Salmonella infection and improves piglets' intestinal health

This study evaluated Bacillus subtilis YB-X-721 in alleviating Salmonella Typhimurium -induced colonic inflammation and immune responses in mice, supporting probiotic alternatives to antibiotics against salmonellosis in livestock. B. subtilis YB-X-721 was isolated from the feces of adult pigs. In vitro experiments showed that this strain exhibits strong acid and bile salt resistance. It also demonstrates good intestinal colonization potential and shows inhibitory effects against Salmonella . An experimental model of colitis induced by S. typhimurium in mice was established to evaluate the protective effects of YB-X-721 against intestinal inflammation. Results showed that pre-treatment with YB-X-721 alleviates body weight loss, colon shortening and epithelial cell shedding, and reduces goblet cell depletion in colitis mice. Further, YB-X-721 decreases levels of MDA, TNF-α, and IL-1β, and increases IL-4 and IL-10 levels. It also enhances activities of T-SOD and CAT, and increases T-AOC content, thus mitigating colonic inflammation. Further analysis reveals that YB-X-721 increases the abundance of beneficial bacteria ( Roseburia and Turicibacter ) and decreases the abundance of harmful bacteria ( Salmonella ). It synergistically alleviates intestinal inflammatory injury by modulating proline, arginine, and tryptophan metabolism, as well as bile acid metabolic pathways. Furthermore, in the application experiments on weaned piglets, YB-X-721 supplementation significantly reduced diarrhea incidence, improved growth performance and antioxidant status, suppressed gut pathogens ( Escherichia coli and Salmonella ), and enhanced Lactobacillus colonization. In summary, B. subtilis YB-X-721 can regulate the intestinal flora and metabolism of mice, alleviate S. typhimurium -induced colonic inflammation in mice, and improve the intestinal health and growth performance of weaned piglets.