Displacement of bacterial pathogens from mucus and Caco-2 cell surface by lactobacilli

1 Department of Microbiology, Faculty of Medicine, National University of Singapore, 5 Science Drive 2, Singapore 117597 2 Department of Biochemistry and Food Chemistry, University of Turku, Fin-20014 Turku, Finland Correspondence Yuan-Kun Lee micleeyk{at}nus.edu.sg Received June 24, 2002 Accepted December 24, 2002 Competition, competitive exclusion and displacement of eight strains of Escherichia coli and Salmonella spp. by Lactobacillus rhamnosus GG and Lactobacillus casei Shirota from adhesion on human intestinal mucus glycoproteins and Caco-2 cell surfaces were studied. Lactobacilli were able to compete with, exclude and displace pathogenic gastrointestinal (GI) bacteria when they were incubated together, but the degree of inhibition of adhesion was bacterial strain-dependent. Competition and exclusion profiles of GI bacteria by lactobacilli were similar. Displacement profiles of GI bacteria were different from those of competition and exclusion and the process was relatively slow: displacement equilibrium took more than 2 h. These findings are important for development, selection and in vitro assessment of target- and function-specific probiotics. Abbreviations: GI, gastrointestinal; LCS, Lactobacillus casei Shirota; LGG, Lactobacillus rhamnosus GG.