| Bifidobacterium spp are main probiotic microorganisms in the gut of human being, whose extracellular polysaccharide(EPS) are related to many physiological functions, such as treatment of constipation, protection of liver, and prevention of tumor etc. However, the probiotic functions and mechanism of Bifidobacterium EPS has been rarely characterized, when compared with fungal polysaccharides and other bacterial polysaccharides. In our study, the effect of Bifidobacterium EPS on intestinal microflora, somatic cell and animal were carried out to evaluate its probiotic functions and mechanisms.Firstly, to evaluate the influence of the EPS on the composition and function of the intestinal flora in mice, five kinds of EPS Bifidobacterium(B. bifidum WBBI01, B. bifidum WBIN03, B. breve WBBR04, B.infants WBAN07 and B. longum WBLO01) were orally gavaged in mice for 28 days, mice administered PBS were served as control. The number of main bacterial flora in the gut and multiple functional indicators were monitored weekly. The results showed that five kinds of Bifidobacterium EPS had positive regulatory effect on the composition, the ability of resistant acid and bile salt, and metabolic capacity of intestinal flora. Compared with other four EPS, B. breve WBBR04 EPS had significant effect on improving the ability of resistant bile salts and acids of intestinal flora, and also improved metabolic capacity, the clearance abilities of DPPH free radicals, ultra oxygen anion, hydroxyl free radical and the total reducing power. As the result shown, the other four kinds of Bifidobacterium EPS have also improved these abilities.Secondly, for further exploring the probiotic mechanisms and potential functions of Bifidobacterium EPS, 10 related indicators(UA, BUN, ALT, CREA, DBIL, TBIL, AST, TG, GLU and T-CHOL) were tested to evaluate the effect of BifidobacteriumEPS on the liver, kidney and serum. As the result shown, five EPS had hypoglycemic effect and significantly reduce the UA, CREA and BUN level. To test the influence of EPS on the signaling pathway, EPS were co-incubated with intestinal epithelial cells HT-29 and Caco-2, respectively, the result showed that the different kinds of EPS had different regulation functions to different signaling pathways factor. Besides, all of the Bifidobacterium EPS increased the m RNA expression level of PHF1 and ARPC2, indicating that EPS might affect neural cell differentiation process and antagonism against tumor. Different EPS present its different effect on different cell signaling pathways, indicating function diversity of Bifidobacterium EPS.Finally, by monitoring the indexes i.e. Ig E, Ig G, IL-4, IL-5, IL-13 and INF-γ of serum of allergic model mice established by immunization of mice with ovalbumin(OVA), the anti-allergic function was tested by administration of the mice with five different Bifidobacterium EPS. The result demonstrated that the B. breve WBBR04, B. infants WBAN07 and B. longum WBLO01 EPS had great anti-allergic effect. To further understand the mechanism of EPS, a co-incubation of colon of model mice with EPS and subsequent with OVA then with EPS, was performed, the change of IL-4 and INF-γ level was determined, the results confirmed that regulation mechanism of Bifidobacterium EPS on mice allergic reaction was due to physical barrier in colon to isolate allergens in gut.In summary, probiotic mechanisms and biological functions were explored systematically according to aspects of intestinal flora from the macroscopic observation, thus provided novel reference for development of microecology theory. Analysis of the changing of transciptom level in epithelial cell lines by EPS, found up a basis for ascertaining probiotic mechanisms of Bifidobacterium EPS. The positive anti-allergic effect of EPS indicated that important theoretical value and development was also set up for prevention of food allergy and transplantationimmunity as well for the development of novel products of EPS from probiotic microorganisms. |
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