奶牛瘤胃未培养尿素分解菌群的磁性纳米分离及元基因组解析

项目名称： 奶牛瘤胃未培养尿素分解菌群的磁性纳米分离及元基因组解析

项目编号： No.31501981

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 畜牧学与草地科学

项目作者： 赵圣国

作者单位： 中国农业科学院北京畜牧兽医研究所

项目金额： 22万元

中文摘要： 尿素是反刍动物重要的非蛋白氮饲料，而尿素在瘤胃中的过快分解易导致尿素利用率降低和氮素过度排放。前期研究发现，瘤胃尿素分解菌群多样性高且99%以上属于未培养细菌。而现有技术无法有效揭示尿素分解菌群的种类和原位功能，限制了对尿素分解机理和调控机制的认知。本项目针对瘤胃未培养尿素分解菌群难以分离以及功能基因认识缺乏的科学问题，提出利用磁性纳米分离和元基因组测序技术研究未培养尿素分解菌群构成和功能的科学假设。研究磁性纳米材料在瘤胃液中的稳定性，建立适合瘤胃液环境的高效磁性纳米分离技术，实现对未培养尿素分解菌群捕获和分离；研究分离的未培养尿素分解菌群功能，评价其原位生态结构与功能特征；利用高通量测序技术研究未培养尿素分解菌群构成和系统发育，解析元基因组信息，寻找与尿素代谢相关功能基因。预期将获得瘤胃未培养尿素分解菌群并阐明其构成和功能，为进一步揭示尿素分解菌群的尿素分解和调控机理提供理论依据。

中文关键词： 瘤胃；未培养尿素分解菌群；磁性纳米；元基因组；群落结构

英文摘要： Urea is an important non-protein nitrogen source in the diet of ruminants. Nevertheless, urea is rapidly hydrolyzed by ureolytic bacteria to ammonia in the rumen of dairy cows, and such rapid ureolysis decreased urea nitrogen utilization efficiency and excessive nitrogen excretion to the environment. In our previous studies, it was revealed that the ureolytic bacteria in the rumen are of high diversity but 99% of them are yet uncultured based on pyrosequencing analysis. However, there is still lack of physiological tool to study the taxonomy and functions of those uncultured ureolytic bacteria, and to further discuss mechanisms and regulations of urea degrading. To isolate living community of the uncultured ureolytic bacteria and obtain its metagenome, this project will develop an integral analysis system combining magnetic nanoparticle mediated isolation and pyrosequencing. Through magnetic nanoparticles stability test in the rumen fluid, the magnetic nanoparticle mediated isolation will be optimized and first-time applied for uncultured ureolytic bacterial community isolation in the rumen. From the physiological evaluation of ureolytic activities of uncultured ureolytic bacteria and original rumen microbial community, this work will uncover the ecological functions of targeting bacteria in the rumen. Via taxonomy analysis of uncultured ureolytic bacterial community by pyrosequencing, the metagenome will be constructed to identify and link the functional ureolytic genes to in situ urea degrading performance. From these cutting-edge techniques, this project can reveal the structure and functions of real ureolytic bacteria community and contribute to deeper understanding on the mechanism and regulation of urea degradation in the rumen.

英文关键词： rumen;uncultured ureolytic bacteria;magnetic nanoparticle;metagenome;community composition