| Functional oligosaccharides which cannot be digested by human enzyme can not exert their interesting effect until they arrive in the intestinal tract. Subsequently, the beneficial bacteria in tract will metabolize these oligosaccharides selectively as the optimized carbohydrate source. Moreover, these oligosaccharides also can inhibit the pathogens adherence to epithelial cells and enhance the mucosal immune response. Recently, in the market there are some oligosaccharides products aiming to protect human and animal such as fructooligosaccharides (FOS), galactooligosaccharides (GOS), mannooligosaccharides (MOS) and chitooligosaccharides (COS). However, because of the lack of the systemic research on the effection mechanism, the functions of oligosaccharides are usually misleaded. Accordingly, in our experiment, we focused on the oligosaccharides feature of the influence to intestinal ecology and physiology. In the level of cell, the adherence inhibition of intestinal pathogen and beneficial bacteria was investigated by four selected oligosaccharides, and the oligosaccharides influence to selected lactobacillus was also discussed. In addition, we adopted the model of mouse to further study the intestinal physiology metabolism, immune response, intestinal micro-ecology change and the protection effect to acute intestinal inflammation.Main contents are as follows:(1) The elementary analyse on physical and chemic property of selected oligosaccharides; the research on grow and pathogen inhibition of two selected lactobacilli, and the influence of the bacteria in stress environment added with selected oligosaccharides.(2) The evaluation on the adherence ability of selected intestinal lactobacilli and pathogen on the HT-29 cell model; the influence of oligosaccharides to the adherence of pathogen and lactobacilli.(3) We adopted the normal Balb/c mouse model, and by gavage method, discussed the oligosaccharides effect on intestinal mucosal tissue, intestinal micro-ecology, mineral absorption, short chain fatty acids (SCFA) metabolism, digest enzyme activity and mucosal immune response.(4) We developed the mouse model of acute intestinal inflammation by the dextran sulfate sodium, and investigated the mouse growth, intestinal tissue injury, activity of disease index (ADI) and immune response by gavage of fructooligosaccharides, galactooligosaccharides and L. acidophilus. Main results are as follows:(1) The molecular weight of four selected oligosaccharides is between 450 and 800. The infrared spectra of these substances had the oligosaccharides characteristics. And oligosaccharides showed strong heat stability, wet absortion and retention ability. Two lactobacilli, L. acidophilus and L. delbrueckii, showed obvious inhibition effect to the pathogen, E. coli, V. parahaemolyticus and Aeromonas hydrophila. Among the components of lactobacilli, the spent culture supernatant exhibited the strongest anti-pathogen ability. Four oligosaccharides namely FOS, MOS, COS and GOS can be metabolized as the optimized carbohydrate source. Moreover, these oligosaccharides, especially FOS and GOS, proved the livability of selected lactobacilli in high temperature, freeze dry, cold preservation and artificial gastrointestinal juice (P<0.05).(2) The adherence test on HT-29 cells showed that adherence rate of L. acidophilus, E. coli and S. aureus were 14%,25% and 22%., and the invasion rate were 0,5% and 2%, and the cell injury rate were 0.71%,6.8% and 4.14%. In addition, the SCS of L. acidophilus had the strong inhibition effect to adherence of two pathogens (E. coli and S. aureus). Four selected oligosaccharides owned certain anti-adherence ability to the two pathogens. The strongest anti-adherence oligosaccharide to pathogens was GOS and MOS respectively.(3) By gavage of 1000mg/kg·d oligosaccharides per mice, FOS, MOS and COS can improve the thymus index of mouse. In addition, the mineral- absorption was affected by the treatment of oligosaccharides. Also the concentration of SCFA, the weight of content in colon or caecum, the count of lactobacilli and bifidobacteria and the weight of caecum wall were improved. Moreover, the treatment of L. acidophilus had more obvious referred effects.(4) Within the process of inflammation model-setting, the gavage of FOS, GOS, L. acidophilus and compound substance decreased the ADI, the injury of colon tissue and activity of myeloperoxidase (MPO) compared to normal saline group (P<0.05).In conclusion, FOS, COS, MOS and GOS can be used as the optimized carbohydrate source, enhance the anti-stress ability and livability of lactobacilli. Meanwhile, the four oligosaccharides especially FOS and MOS had certain inhibition ability to epithelial cell adherence of E. coli and S. aureus. Moreover, the feed of these oligosaccharides to mouse enhance the immune response, improved the absorption of calcium, magnesium and iron, and increase the lactobacilli and bifidobacteria which made the intestine physiology balanceable and healthy. |
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