engleski

S-layer-expressing Lactobacillus strains in competitive exclusion of pathogens

Competition of commensal and probiotic bacteria with pathogens for colonization of colon is one of the protective mechanisms of human gastrointestinal tract. To be able to successfully compete with pathogens for binding sites, probiotic bacteria must have advanced adhesion properties. Since in our previous work we have shown that specific surface proteins, named S-layer proteins, have important role in adhesion of bacterial cells, in this study, we examined the ability of five S-layer-expressing Lactobacillus strains to inhibit the adhesion of Salmonella enterica serovar Typhimurim FP1 and Escherichia coli 3014 to human colon adenocarcinoma Caco-2 cells. Two types of experiments were done: preincubation (lactobacilli were incubated with Caco-2 cells first, after which potentially pathogenic bacteria were added) and coincubation (both bacteria were added to Caco-2 cells simultaneously). The number of adherred potentially pathogenic bacteria decreased in lesser extent in coincubation experiment than in the case of preincubation of Lactobacillus strains, when they were given advantage in creating interaction with Caco-2 cells. It is also important to emphasise that all of the five Lactobacillus strains showed antimicrobial activity against both of the potentially pathogenic strains, which is aditional mechanism of prevention of pathogen colonisation in human gastrointestinal tract.

S-layer ; Lactobacillus ; competitive exclusion

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