Study On The Inhibition Of Chicken Pathogenic E.coli Binding To Chicken Intestinal Brush Border Membrane By Probioties

The study treated chicken Intestinal mucous membrane as the model and selected two probio- tics (L. acidophilus and L.casei) and an avian pathogenic E. coli as research objects, to investiga- te the competitive exclusion mechanism of probiotics by lectin-binding histochemistry ABC and solid phase binding and binding inhibition assay.Healthy new born broiler chicken were selected and divide into six groups in randomly to est- ablish experimental animal model.One group were normal bred, one administration avian pathoge- nic E. coli, other groups administration L. acidophilus,L.casei,mixture of L. acidophilus and L casei and mixture of L. acidophilus and L.casei followed avian pathogenic E. coli in difference. All group animals Intestinal mucous membrane were studied with lectin- binding histochemistry ABC to validate probiotic whether or not have the capacity to change some specific glycosylation state. In addition, intestinal brush border membranes and bacterial adhesions were extracted to do Solid phase binding and binding inhibition assay, and analyzed by Scatchard plot and Hill plot. To inve- stigate the mechanism of probiotic inhibition pathogenic bacteria from molecular directions.The results showed that D-mannose conjugates in the brush border membranes was the main receptor of pathogenic E. coli, small amounts N- acetylneuraminic acid conjugates also related L-fu- cose conjugates and N-acetylglucosamine wre possible the receptor of L. acidophilus. N-acetyl- neuraminic acid was the main receptor of L.casei, besides galactose conjugates also related the rec- eptor.Two probiotics and avian pathogenic E. coli all able to modify some specific glycosylation state E. coli could improve the expression of D-mannose lectin receptor and N-acetylneuraminic acid l- ectin receptor in intestinal brush border membrane of all sections except ileum, but N-acetylneura- minic acid lectin receptor increase smaller; L. acidophilus increased the expression of L-fucose lec- tin receptor and also N-acetylglucosamine lectin receptor; The expression of galactose lectin receptor and N-acetylneuraminic acid lectin receptor also improved by L.casei. Furthermore, the expression D-mannose lectin receptor in chicken intestinal mucous membrane which fed probiotics all degraded a little, but difference quiet.The interaction of adhesions of two probiotics and fimbriae of E. coli with intestinal brush border membrane all depended on concentration and time, and temperature had no effect. From an analysis of a Hill plot, surface layer protein of L. acidophilus and L.casei existence multitude kinds of binding sites in brush border membrane, Furthermore, the affinity of every site is diversity, it was the possible reason that every probiotic could inhibited the binding of diverse pathogens with host. The fimbriae of E. coli also had two kinds of binding sites in brush border membrane, of high and low affinity , and the existence of negative cooperativity between identical binding sites.but the WPG of two probiotics cell walls all only had one binding site, and some positive cooperative effect was found in WPG- brush border membrane system. S- layer protein and WPG of two probiotics all able to inhibit the binding of fimbriae with brush border membrane, but S- layer protein stronger than WPG. The maximum bound of fimbriae decreased a little with small amounts adhesions of probiotic presence, but the bound of non-specificity degraded significantly; While mass adhesions of probiotic were presented The maximum bound of fimbriae decreased significantly, and non-specificity close to nought, and fimbriae only have one binding site, the affinity also degraded significantly.