尿素是主要的非蛋白氮饲料，合理利用尿素可在一定程度上缓解我国蛋白质饲料资源短缺的现状。尿素在反刍动物瘤胃尿素分解菌的作用下快速分解，但是由于89%左右的瘤胃微生物难以分离培养，所以目前对瘤胃尿素分解菌代谢尿素的机理仍不清楚，限制了尿素在反刍动物生产中的应用。本项目在前期尿素分解菌分离与多样性初步探析、脲酶抗体和抑制剂研究的基础上，利用元基因（转录）组学方法,研究瘤胃尿素分解菌群落结构特征，解析具有代谢活性的尿素分解优势菌（群）;通过瘤胃原位分离培养和单细胞分离测序的方法，对尿素分解优势菌进行分离培养;构建尿素分解菌脲酶基因簇，研究尿素代谢相关基因的功能;基于功能基因信息，阐明瘤胃脲酶活化模式，绘制尿素代谢的基因通路，寻找尿素代谢调控靶点。本项目的执行可揭示尿素在瘤胃分解的微生物和分子机理，为提高尿素营养利用率提供理论基础和调控途径。

Urea is one of the major non-protein nitrogen feed for ruminants and the optimal utilization of urea in feed can alleviate to some extent the shortage of protein feed resources in China. Urea is hydrolysed quickly by ureolytic bacteria and urease in rumen. Since about 89% rumen microbe could not be pure-cultured, there is little information about active abundant ureolytic bacteria community, urease genes and mechanism of urea metabolism, which limits the regulation and application of urea in ruminant production. During our previous studies, we have isolated several ureolytic bacteria, revealed the primary diversity of ureolytic bacteria, and evaluated effects of urease antibody and inhibitors on urease activity in the rumen. In this project, rumen ureolytic bacteria diversity will be analyzed based on metagenomics, and the active abundant ureolytic bacteria community will be analyzed using metatranscriptomics. The abundant ureolytic bacteria or cells will be isolated using the method of in situ culturing and single cell sequencing, and the genomes of ureolytic bacteria will be annotated as well. Based on the construction for urease gene clusters, further functions of genes related to urea metabolism will be studied. The urease activation model and pathway of urea metabolism will be constructed based on the information of functional genes related to urea metabolism. Conduct of this project will help understand the microbial and molecular mechanism of rumen urea hydrolyzation, and further to provide the knowledge building pathways for urea hydrolyzation in rumen.