Study On Mechanism Of Lactic Acid Bacteria Adhering To Mice Peyer's Patches

Peyer's patch (PP) is the main site of mucosa immunity system through which lactic acid bacteria (LAB) come into contact with immune active cells to modulate their functions. This study is focused on adhesion of LAB to mice PP in vitro and the main factors involved in. The aim is to give some explanation on mechanism that LAB modulat host immune function, and to help developing immune modulation foods and products related to LAB.Adhesion of 10 FITC labeled LAB strains to PP paraffin section was analyzed and L. acidophilus (LA) shows the best ability. Hydrophobicity of all strains was studied using BATH assay. A negative correlations trend was found between the hydrophobicity and adhersion. Expression of lectin on bacterial surface was studied using hemagglutination (HA) test and yeast agglutination test. A significant positive correlation was found between agglutination and adhesion. LA shows the best agglutination.A significant reduction of HA titers occurred due to the treatment of E. coli (control) and LA with protease, trypsin, SDS or LiCl. Hemagglutination of E. coli and LA had been mainly inhibited by D(+)-mannose and D(+)-galactose. HA activity of E. coli was abolished when erythrocytes had been treated withα-galactosidase. All the results demonstrated that it was the glycoproteinous substances surrounding the surface of the bacterial cells that were responsible for the adhesion of these microorganisms by recognizing the specific receptors on the red blood cell.In order to determine the mediator involved in adhesion of LA to PP quantitatively, a fluorescent quantitation method was developed. Adhesion of FITC labeled LA to PP was studied in 96-well plate. PP was washed to remove unadhereing bacteria before digestion. Adhering bacteria was determined by fluorescence value. The optimumed detecting condition was: incubation for a hour under 37℃with 1×109CFU/mL of LA, washing three times, digesting tissue in 1%(Triton X-100+KOH)for 18 hours under 70℃. It shows that the adhersion of LA to PP would be inhibited by D(+)-mannose and methyl-D-mannoside. Considering the result from HA, it could be concluded that the adhesion mediator of LA was mannose specific lectin like material.LA and E.coli have some similar carbohydrate specificity when they adhere to PP, therefore, it was possible to use LA as inhibitor for E. coli invaded PP. The competitive adhesion study show that both the viable and the inactivated LA could inhibit the adhersion of E. coli, Salmonella and Shigella to PP, and inactivated LA shows better inhibition to E.coli.