本研究探讨黄精多糖体外消化特性、体外降血糖活性及对Ⅱ型糖尿病鼠肠道菌群的调节作用。以空白作对照，对黄精多糖进行体外消化，采用DNS法和凝胶色谱法测定黄精多糖在消化过程中还原糖含量和分子量的变化；对黄精多糖进行体外酵解实验，对酵解物进行16S rDNA分析，研究黄精多糖对糖尿病鼠肠道菌群的影响。研究结果表明，在胃部消化模拟阶段，黄精多糖相对分子质量从24.19 ku降低到20.39 ku，在肠道消化模拟级阶段，相对分子质量从28.85 ku降低至24.35 ku，说明黄精多糖经过消化过程后大部分能够到达肠道末端被肠道菌群利用，少量被直接消化吸收。通过对酵解液细菌16S rDNA的测序分析结果进行α多样性分析和β多样性分析，黄精多糖显著提高肠道菌群的丰富度和多样性，改变菌群物种组成结构；在门水平上，黄精多糖显著改变优势菌门厚壁菌门、变形菌门和拟杆菌门的相对丰度；在属水平上，黄精多糖显著改变乳酸菌属、韦荣氏球菌属、埃希氏菌属、克雷伯氏菌属等优势菌属的相对丰度，结果表明，黄精多糖可以通过对糖尿病鼠的肠道菌群进行调节进而起到一定的改善病情作用。

In this study, the in vitro digestion characteristics, in vitro hypoglycemic activity and regulatory action of Polygonatum sibiricum polysaccharides towards gut microbiota in type 2 diabetes (T2DM) mice were investigated. With the blank as a control, Polygonatum sibiricum polysaccharide was subjected to in vitro digestion, and the changes in the content of reducing sugars and molecular weight of Polygonatum sibiricum polysaccharides during the digestion were evaluated by the DNS method and gel chromatography. The in vitro fermentation of Polygonatum sibiricum polysaccharide was conducted, and the resulting products were subjected to 16S rDNA analysis to examine the effect of Polygonatum sibiricum polysaccharide on gut microbiota of T2DM mice. The obtained results showed that During the simulated stomach digestion, the molecular weight of Polygonatum sibiricum polysaccharides decreased from 24.19 ku to 20.39 ku, and during the simulated intestinal digestion, the molecular weight decreased from 28.85 ku to 24.35 ku. These results showed that most of Polygonatum sibiricum polysaccharides could reach the end of intestine after digestion and could be utilized by gut microbiota, with a small amount being directly digested and absorbed. Through the analysis of α diversity and β diversity based on the 16S rDNA sequencing analysis of the bacteria in the fermentation liquid, Polygonatum sibiricum polysaccharides were found to increase significantly the abundance and diversity of the gut microbiota and change the composition of the microbiota. At the phylum level, Polygonatum sibiricum polysaccharides significantly changed the relative abundance of the dominant phylum Firmicutes, Proteobacteria and Bacteroides. At the genus level, Polygonatum sibiricum polysaccharides changed significantly the relative abundance of dominant genus such as Lactobacillus, Veillonella, Escherichia and Klebsiella. The results showed that Polygonatum sibiricum polysaccharides could improve the condition of diabetic mice through regulating their gut microbiota.

国家自然科学基金青年基金项目（32000252）；黑龙江省科学基金优秀青年基金项目（YQ2020C014）；中国博士后科学基金面上项目（2019M661236）；黑龙江省大学生创新创业训练计划项目（201910225203）