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Characterization of Lactobacillus acidophilus M92 Traits Related to Adhesion

Lactobacilli are major microorganisms of the normal human microbiota, and the determination of the mechanisms through which they colonize the intestinal tract may provide important insight into how the normal microbiota is maintained as well as provide a basis for the selection of probiotic strains. The ability of probiotic bacteria to adhere to the intestinal epithelium play an important role in colonization of the gastrointestinal tract, preventing their elimination by peristalsis and providing a competitive advantage in this ecosystem. To identify bacterial traits related to adhesion the probiotic strain L. acidophilus M92 was examined for autoaggregation ability and cell surface hydrophobicity. L. acidophilus M92 exhibits a strong autoaggregating phenotype and also coaggregation with some pathogen microorganisms that may form a barrier that prevents their colonization. The examined probiotic strain manifests a high degree of hydrophobicity determined by microbial adhesion to hydrocarbons. Aggregation and hydrophobicity were abolished upon exposure of the cells to pronase and pepsin, which suggest the possible role of cell surface proteins in the aggregation phenotype. SDS-PAGE of cell surface proteins revealed the presence of potential surface (S-) layer proteins, approximated at 45 kDa, in L. acidophilus M92. The relationship between autoaggregation and adhesion ability to intestinal tissue was investigated by observing the adhesivity of L. acidophilus M92 to porcine ileal epithelial cells. Removal of the S-layer proteins by extraction with 5 M LiCl reduced autoaggregation and in vitro adhesion of this strain.

Lactobacillus acidiophilus; adhesion; S-layer; probiotics

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