Adherence of Probiotic Bacteria to Human Colonic Cells

Abstract

Bifidobacteria showed better adherence to monolayer Ht-29 colonic cancer cells as compared with Lactobacillus acidophilus. Among bifidobacteria, Bifidobacterium infantis 1912 and B. longum 1941 showed highest level of adherence. Among L. acidophilus, strains 2400 and 2415 showed best adherence. Thus, in general, bifidobacteria may be preferred as dietary adjuncts over L. acidophilus. Proteins were found to be present in spent broth of all strains of adhering bacteria involved in adherence of probiotic bacteria to Ht-29 cells. However, involvement of polysaccharides from bacteria and Ht-29 cells for adherence varied from strain to strain of probiotic bacteria. Polysaccharides produced by Ht-29 cell surfaces contributed to adherence than those originating from the bacterial cells. For B. infantis 1912 and B. longum 1941, polysaccharides of both bacterial and Ht-29 origin were involved in adherence. The molecular size of proteins involved in adherence varied among the strains of probiotic bacteria. In B. longum 1941 and B. infantis 1912, a molecular size fraction of 30, 000-50, 000 kDa was responsible for adherence. Adherence was mediated by a bridging structure (possibly a protein-polysaccharide structure) formed between bacterial and Ht-29 cells.