Protective action of S-layer proteins from Lactobacillus paracasei M7 against Salmonella infection

Surface-layer proteins are located in a paracrystalline layer outside the bacterial cell wall and are thought to play a role in the adherence. However, the functions of S-layer proteins are not yet completely revealed and it has been proposed that these structures protect the microbe from hostile environmental agents and aid in maintaining cellular integrity. In this study, the Lactobacillus paracasei M7 strains showed to inhibit the adhesion of Salmonella to epithelial cells, a process which may be related to specific component of the bacterial surface. Human epithelial HT-29 cells were treated with S-layer proteins after Salmonella infection, or were pretreated with S-layer proteins prior to infection to determine their importance in the inhibition of pathogen adherence.