Scanning Electron Microscopy observation of adhesion properties of Bifidobacterium longum W11 and chromatographic analysis of its exopolysaccaride.

Bifidobacterium spp. can produce cell-bound or released exopolysaccharide (EPS) that is a beneficial trait mediating commensal-host interactions. However differences in the physico-chemical characteristics of EPS produced by different strains of Bifidobacterium spp. are determinant in adhesion ability and modulation of immune response. The aim of this study was to investigate the in vitro adhesion characteristics of Bifidobacterium longum W11 to intestinal epithelial cell-line HT-29, by Scanning Electron Microscopy (SEM), and chemical characteristics of its exopolysaccharide using Thin-Layer Chromatography (TLC) analysis. SEM observation showed a good adhesion of B. longum W11 to the HT-29 monolayer that could be increased by the production of exocellular polymers formation. TLC analysis of the purified and hydrolyzed EPS showed that the cell-surface and extracellular polysaccharide were composed mainly of fructose and glucose. Moreover, other sugars were present in smaller quantities. Information from this study on physico-chemical characteristics of EPS of B. longum W11 could contribute to understanding the physiology of bifidobacteria and their interaction with the host.