鱼类对碳水化合物的利用障碍是著名的鱼类营养学难题。相较于大部分鱼类，罗非鱼具有较好的碳水化合物利用率，但其生物学机制尚不明确。当前已知肠道微生物在高等动物碳水化合物利用中发挥重要作用，我们也已发现罗非鱼肠道中存在多种可降解淀粉的微生物类群，因此我们提出假说认为：罗非鱼的肠道菌群在其糖代谢中扮演重要角色。为验证此假说，本项目拟首先深入分析糖耐受能力不同的罗非鱼、草鱼、大口黑鲈肠道内淀粉降解菌的丰度及组成差异，绘制精细的菌群组成图谱。其次，依据图谱靶向分离罗非鱼肠道目标菌及其代谢产物，通过饲料口服与细胞暴露等手段，借助代谢示踪、通路调控和无菌斑马鱼验证等技术，探究靶标菌群通过短链脂肪酸/胰岛素通路和肠道屏障调节等潜在途径提高罗非鱼糖代谢效能的生物学机制。最后，拟通过菌群接种，在草鱼和大口黑鲈中确认功能菌对提高鱼类碳水化合物利用能力是否具有普适性，从而为建立鱼类糖代谢调控技术提供必要的基础。

Fish in general utilize dietary carbohydrates poorly. Compared to most fishes, Nile Tilapia is known to be a good user of carbohydrates, but the mechanism remains unknown. Intestinal microbiota plays important roles in carbohydrates utilization and many starch-degrading bacteria have been found in the gut of Nile Tilapia in our previous research. We hypothesize that intestinal microbiota help Nile tilapia to adapt to high level of dietary carbohydrate. This project will analyze the intestinal bacterial composition in Nile tilapia, Grass carp and Perch, which will afford comprehensive information of functional bacteria in different fishes. Then the functional bacteria or metabolites in the gut of Nile Tilapia will be isolated. Tracing the fate of carbohydrates metabolites, regulation of short chain fatty acids (SCFA) or insulin related signal pathways and colonization of germ-free zebrafish will be applied to identify the possible role of intestinal bacteria or metabolites in the adaptation of fish to high level of diet carbohydrate. Last, the functional bacteria will be transferred into the gut of grass carp or perch to check whether the function of intestinal bacteria in the utilization of carbohydrates is conserved among different species.