Adhesion of Two Lactobacillus Strains, One Lactococcus and One Propionibacterium Strain to Cultured Human Intestinal Caco-2 Cell Line

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Adhesion to intestinal surfaces is considered a prerequisite for effective probiotic bacterial strains. In this study, the in vitro adhesion properties of dairy strains Lactobacillus rhamnosus LC-705, Lactococcus lactis ssp. cremoris ARH 74 and Propionibacterium freudenreichii ssp. shermanii JS were investigated using human intestinal Caco-2 cell cultures. Lactobacillus strain GG (ATCC 53103) was used as a positive probiotic control, because the strain is known to adhere to Caco-2 cell cultures. Enterotoxigenic human E. coli (H 10407) and bovine E. coli (B 44) strains were used as positive and negative control, respectively. Bacteria were radioactively labeled, and the adhesion to Caco-2 cell cultures was assessed using liquid scintillation. The tested strains adhered to Caco-2 cell cultures and the adherence was similar to that of Lactobacillus strain GG. The adhesion was significantly higher when compared to the negative E. coli control. Adhesion was concentration dependent and no saturation level was achieved with bacterial concentrations used in this study. The Caco-2 cell cultures were also pretreated with nonlabeled bacteria of one strain prior to adhesion of radiolabeled bacteria. The nonlabeled adhered bacteria influenced the adhesion of radiolabeled bacteria in only one case: the adhesion of P. freudenreichii was significantly reduced by previously adhered L. rhamnosus LC-705. This result may indicate competition for adhesion sites between these strains. The adhesion properties of Lc. lactis and P. freudenreichii to intestinal cells make the strains interesting as potential new probiotic strains.