Intestinal barrier integrity is a prerequisite for homeostasis of mucosal function, which is responsible for increasing absorptive capacity without disturbing efficient defensive reactions against chemical and microbial challenges. Evidence is mounting that disruption of epithelial barrier integrity is one of the major aetiological factors associated with several gastrointestinal diseases, including pathogen infection, obesity, diabetes, inflammatory bowel disease, irritable bowel syndrome and necrotising enterocolitis. However, there are indications that probiotic strains of lactic acid bacteria (LAB) can positively affect intestinal barrier integrity, which led to increased intensity of researches in which in vitro cell lines, animal models and clinical trials assess whether probiotics, when applied in people, can revert to homeostasis and health. Among potential probiotic strains of LAB, species of the genus Lactobacillus stand out, especially strains which express layer of specific S-proteins on the cell surface. In this work, the ability of probiotic strain Lactobacillus brevis SF9B to regenerate the layer of S-protein after exposure of the cells to stimulated conditions of gastrointestinal tract was examined. The role of S-protein in competitive exclusion of bacteria Listeria monocytogenes ATCC 19111 and Staphylococcus aureus 3048 with the same probiotic strain in in vitro experiments using intestinal epithelial cells of Caco-2 cell line was also tested.