| There is substantial evidence suggesting that lactic acid bacteria (LAB) have an inhibitory effect on pathogenic bacteria in the intestinal tract. LAB, and LAB used for manufacturing cultured dairy foods, have been shown to modify the metabolic activities of the colonic microflora, possess antimicrobial activity, and neutralize Escherichia coli (E. coli ) enterotoxin. Although various mechanisms have been proposed for these effects, the involvement of LAB gangliosides contained in these products was the focus of this research.; Mixed gangliosides were extracted and purified from sweet and cultured buttermilk, LAB, and yogurt. These products were targeted because it is known that they contain gangliosides. Using an agar overlay plate technique, mixed gangliosides recovered from these products demonstrated bacteriostatic effects, as evidenced by the retardation of E. coli growth around wells containing varying amounts of gangliosides. Mixed gangliosides have also demonstrated inhibition of mannose-resistant pilus-mediated adhesion of E. coli. The hemagglutination-inhibition assay results suggest that gangliosides may limit the adhesion of enterotoxigenic E. coli to the intestinal mucosa and thus prevent diarrhea. The application of this research to Helicobacter pylori (a bacterium strongly associated with gastric ulcers) was demonstrated by inhibition of pilus-mediated adhesion of this organism as determined by the hemagglutination-inhibition assay. |
