Lactobacillus plantarum regulated intestinal microbial community and cytokines to inhibit Salmonella typhimurium infection

Lactic acid bacteria (LAB) are recognized as food-grade safe microorganisms and have many beneficial effects. LAB could maintain the host intestinal homeostasis, and regulate intestinal microbial community to exert antibacterial effects. In this study, Lactobacillus plantarum ( L. plantarum ) strain isolated from pig intestine was orally administered to C57BL/6 mice, and mice were then infected with Salmonella typhimurium . The protective effects of L. plantarum were evaluated by monitoring body weight loss, survival rates, bacterial loads in tissue, cecal histopathology analysis, and cytokine secretion. 16S rRNA gene sequencing was also utilized to detect the dynamics of the cecal microbial community in C57BL/6 mice. We found that L. plantarum could significantly reduce the body weight loss and improve the survival rates. Counting of bacterial loads displayed that L. plantarum decreased Salmonella transplanting in spleen or liver. Intestinal histopathology showed that it alleviated the intestinal injury caused by Salmonella , inhibited the secretion of pro-inflammatory cytokines and promoted anti-inflammatory cytokines. In addition, L. plantarum also significantly ameliorated the intestinal gut microbiome disturbance caused by Salmonella and restored the balance among dominant gut microbiome. It displayed an obvious increase of beneficial bacteria including Lactobacillus and Bacteroidete s, and reduction of pathogenic bacteria like Proteobacteria . In conclusion, L. plantarum could regulate microbial community to inhibit Salmonella typhimurium infection.