多糖是小球藻中主要功能活性成分之一，但小球藻胞内多糖对肠道菌群和宿主肠道免疫的调节活性及互作机制尚不明确。本项目以对分离纯化后的小球藻Chlorella zofingiensis胞内多糖（CZIP）为研究对象，对其理化特性和结构进行表征；利用小鼠巨噬细胞探究CZIP对巨噬细胞免疫功能的调节活性及作用机制，结合环磷酰胺诱导的免疫抑制小鼠模型，探究CZIP对宿主免疫的调节活性和潜在机制，同时利用高通量测序技术揭示CZIP对小鼠肠道菌群的调节活性及其免疫调节功能的影响，结合相关性分析挖掘CZIP发挥功效的关键肠道微生物和代谢产物，阐明CZIP对肠道菌群和宿主免疫的调节活性及互作机制；最后设计同笼实验并结合免疫抑制小鼠模型来探究CZIP对肠道菌群结构及其免疫调节功能的影响，为微藻多糖的功能活性评价提供新的途径，为微藻资源的联产制备及高附加值产品开发提供科学指导。

Polysaccharide is one of the main functional active ingredients in Chlorella zofingiensis, but the regulatory activity and interaction mechanism of C. zofingiensis polysaccharides on gut microbiota and host gut immunity are not clear. This project takes the isolated and purified C. zofingiensis intracellular polysaccharide (CZIP) as the research object to characterize its physicochemical property and structure. Macrophages from mouse was used to explore the regulatory activity and mechanism of CZIP on the immune function of macrophages, combined with the cyclophosphamide-induced immunosuppressive mouse model to explore the regulatory activity and potential mechanism of CZIP on host immunity. High-throughput sequencing technology was used to reveal the effect of CZIP on the regulatory activity of gut microbiota and its immunoregulatory function, combined with correlation analysis to explore the key gut microbes and metabolites, to clarify the regulatory activity and interaction mechanism of CZIP on gut microbiota and host immunity. Finally, the co-housing experiment was designed and combined with an immunosuppressive mouse model to explore the effect of CZIP on the structure of gut microbiota and its immune regulation function，and provide a new way for the evaluation of the functional activity of microalga polysaccharides, provide scientific guidance for co-production of microalgae resources and development of high value-added products.