双歧杆菌胞外多糖的结构解析及调节肠黏膜免疫机制研究

胞外多糖（exopolysaccharides, EPS）是乳酸菌的重要次生代谢产物，其结构复杂功能多样，可作为功能因子应用于食品。本项目以分离自广西巴马长寿老人肠道的一株双歧杆菌为材料，采用色谱纯化技术制备纯品EPS，应用GPC、HPAEC、GC-MS、NMR、AFM、LLS、X-ray等技术手段分析测定EPS的分子量、单糖组成、连接方式、连接顺序及固体形貌、溶液性质、链构象，解析其初、高级结构特征。同时，以肠黏膜免疫相关淋巴细胞的增殖情况、淋巴细胞亚群变化、细胞因子表达量和抗体分泌量等为指标，通过体外和体内试验探明EPS作用于肠黏膜免疫细胞的位点和方式，最终从细胞和分子水平上揭示该EPS调节肠黏膜免疫功能的作用机制。研究结果不仅为后续EPS构效关系的阐明奠定了理论基础，同时也为新型食品添加剂、保健产品的开发应用提供了新的资源与途径。

The exopolysaccharide (EPS) produced by Bifidobacterium which possesses many beneficial properties, is an important health-promoting secondary metabolite, resulting to its potentially valuable application in food industry as functional ingredients. .This project aims at laying a theoretical foundation for illustrating the stucture-activity relationships of EPS from Bifidobacterium animalis RH, isolated from the feces of Bama centenarians in Guangxi, China. In order to achieve such purpose, the methods of ethanol precipitation, anion exchange chromatography, gel permeation chromatography, HPLC, HPAEC-PAD, periodate oxidation, methylation analysis, GC-MS, NMR spectroscopy, AFM, LLS and X-ray are chosen to determinate and analyze the average molecular mass, monosaccharide composition, primary and advanced structures of EPS. Through the variation of lymphopoiesis, leukomonocyte subgroup, cytokines and antibody production between EPS group and model group induced by CTX both in vitro and in vivo, the regulatory machanism of EPS on intestinal mucosal immunity will be obtained.