多糖和寡糖的体外发酵特性及其对鸡盲肠微生物菌群的影响

In Vitro Fermentation Characteristics of Oligo-and Poly-saccharides and Their Effects on Chicken Cecum Microbial Community

本研究采用体外累积发酵产气法和16SrDNA指纹图谱鉴定技术研究了来自香菇、银耳和黄芪的天然免疫活性多糖(LenE,TreE和AstE)及酵母胞壁甘露寡糖(MOS)对鸡肠道微生物菌群及其发酵特性的影响。结果表明,三种多糖提取物的总糖含量均占干物质的60%以上,而MOS总糖含量在90%以上。多糖和寡糖具有不同的发酵模式;MOS、AstE和LenE三种糖的发酵模式相似,呈一阶段发酵模式;TreE呈两阶段的发酵模式。三种糖中,MOS和AstE发酵速度较TreE快。MOS和AstE在发酵后总VFA产量最高,pH最低;黄芪多糖发酵后产生较多的直链脂肪酸和较低的氨。这些多糖和寡糖提取物影响肠道微生物的活性和组成成分,体现在发酵模式和发酵终产物的显著改变上。以上研究结果表明,来自香菇、银耳和黄芪的天然免疫活性多糖(LenE,TreE和AstE)及酵母胞壁甘露寡糖(MOS)在体外发酵后,均具有显著改变鸡盲肠微生物发酵终产物的含量和盲肠微生物活性的作用。

Manno-oligosaccharide from yeast cell wall and Immuno-active polysaccharides from edible mushrooms may improve animal health through manipulating animal intestinal eco-system and microbial community,and enhancing animal defense system. In vitro accumulative fermentation gas production technique and molecular biological identification technology were used to determine the fermentation characteristics and microbial community of Manno-oligosaccharide （MOS） from yeast cell wall, and natural immuno-active polysaccharides from Lentinus edodes （LenE）, Tremella fuciformis （TreE）, and Astragalus membranaceus （AstE）. The results showed that the total sugar content makes up over 60% of the DM of the mushroom and Astragulas extracts, while that of MOS contains more than 90% sugar. The gas profiles were similar for MOS, AstE and LenE,while Tree had a diphasic digestion pattern. The gas production rate of AstE, MOS and LenE was significantly faster than TreE. Both MOS and AstE had the highest total VFA production and lowest pH value overall. The fermen- tation of the polysaccharide extracts resulted in the production of mainly straight-chain fatty acids and decreased NH3. These oligosaccharide and polysaccharide extracts may influence the activity and composition of microbial population after fermen- tation,both in terms of fermentation characteristics and changes in end-products. Thus the study demonstrated that natural immuno-active polysaccharides, LenE, Tree and AstE, from Lentinus edodes, Tremella fuciformis, and Astragalus membranaceus, and MOS from yeast cell wall significantly altered fermentation end-products and cecal microbial activities after fermentation.