Abstract: The aim of this study was to evaluate the tolerance of Lactobacillus to digestive stress in simulated saliva, gastric juice and intestinal juice, its adhesion capacity to intestinal mucin and Caco-2 cells and its inhibitory capacity against intestinal pathogen adhesion. The effect of digestive stress on the intestinal adhesion capacity of Lactobacillus was also studied. The results showed that the viable counts of L. paracasei?m111 and W125 and L. fermentum 146 were 7.46, 7.24 and 8.35 (lg(CFU/mL)), respectively, and their survival rates were 2.70%, 3.53% and 11.15%, respectively, after sequential exposure to simulated saliva, gastric juice and intestinal juice. Their adhesion rates to mucin were 15.67%, 8.75% and 8.38%, and their adhesion rates to Caco-2 cells were 11.47%, 21.34%, 10.44%, respectively, which were significantly higher than those of the other strains (P < 0.05). Each of the three strains had the capability to inhibit the intestinal adhesion capacity of Escherichia coli CICC10899 and Salmonella WX29 by exclusion, competition or substitution, with an inhibition percentage of more than 13.51%. Digestive stress significantly decreased the intestinal adhesion capacity of L. paracasei W125 and L. fermentum 146 (P < 0.05), but increased the intestinal adhesion capacity of L. paracasei m111 from 17.60% to 30.45% (P < 0.05). After digestive stress, the major adhesins changed from surface proteins to proteins and polysaccharides, the morphology of L. paracasei m111 remained long spindle-like, round rod-like in shape, whereas the thickness of the surface material was not significant changed (P > 0.05). In conclusion, L. paracasei m111 has strong tolerance to digestive stress and consequently strong intestinal adhesion capacity, making it a potential probiotic with a promising future.

Key words: Lactobacillus; digestive stress; adhesion ability