Mechanism of Bacillus coagulans T242 in prevention of Salmonella infection in mice

Abstract

Salmonella is recognized as an important foodborne pathogen, which seriously threatens human safety. Bacillus coagulans T242 (T242) could prevent the growth of Salmonella and alleviate Salmonella infection in Caco-2 cells in vitro. The main objective of this study was to investigate the mechanism of action of T242 in preventing Salmonella infection in mice. Both T242 vegetative cells and spore prevention groups could reduce the bacterial loads in the ileum, liver and spleen of Salmonella typhimurium (S. typhi) SL1344 infected mice, and reduce the levels of Interleukin-10 (IL-10) and tumor necrosis factor-α (TNF-α) in serum and also increase the expression of Interleukin-1β (IL-1β) in serum, Monocyte chemoattractant protein-1 (MCP-1) and Inducible nitric oxide synthase (iNOS) in the liver, Interleukin-22 (IL-22) and Interleukin-23 (IL-23) in the ileum, and tight junction proteins (Claudin-1, Occludin and ZO-1) in the colon, and regulate intestinal flora. Pretreatment of T242 spores could downregulate the relative abundance of Desulfovibrionaceae in Salmonella infected mice. The relative abundance of Ruminococcus in Salmonella-infected mice was down-regulated by T242 vegetative cells preconditioning. The results showed that T242 prevented the systemic spread of Salmonella by regulating intestinal flora and enhancing intestinal barrier function against Salmonella invasion, inducing anti-inflammatory effects and regulating immune responses. T242 had great potential in controlling the epidemic of foodborne pathogens and was expected to be an effective alternative to antibiotic therapy, which is of great significance for the control and defense of Salmonella infection.