Antagonistic activities of Lactobacillus plantarum Guo against enteric pathogens and its protective effect on Caco-2 cells

摘要

The antagonistic activities of Lactobacillus plantarum Guo against the adhesion of Escherichia coli and Salmonella enteritis to Caco-2 cells were compared with the well-investigated Lactobacillus rhamnosus GG with a fluorescent labelling method. The protective effects of the Guo on Caco-2 cells were studied by the analysis of cell membrane permeability. The results of the antagonistic ability of Guo showed significant effects of strain, dose and strain-dose interaction (P<0.05) for E. coli and S. enteritis. The highest inhibition rate (56.97%) was obtained in the exclusion assay of ST-III (1.0 chi 10~9 /ml) against E. coli, indicating that a specific antagonistic effect may be involved between L. plantarum and E. coli. Among the three mechanisms foran antagonistic effect (exclusion, competition and displacement), the most effective way for E. coli inhibition through ST-III was exclusion whereas competition was the most effective mechanism for LGG. In the membrane permeability assay, co-incubationof ST-III with pathogens and Caco-2 cells after 3 h showed dramatic decrease of Caco-2 cells injury. Guo could protect Caco-2 cells by competing for specific receptors or though steric hindrance against pathogens. In conclusion, ST-III could successfullyinhibit the adhesion of enteric pathogens and protect mammalian epithelial cells from being damaged