中文摘要：

采用平板划线分离法从健康奶牛瘤胃液中分离得到1株细菌Y-1,体外模拟瘤胃环境增殖Y-1,进行形态学观察、生化反应和16SrDNA基因同源性比较,并对其进行系统发育树的构建等系统鉴定。结果表明,该细菌为浸麻类芽孢杆菌（Paenibacillus macerans）,本研究还对瘤胃液中存在该菌的原因做了分析。

英文摘要：

We used flat crossed separation method to get a bacterial Y-l, which was isolated from a cow rumen fluid. Simu- lating rumen environment in vitro to proliferate Y-1. The test adopted the methods, which include morphological observation, biochemical reactions and 16S rDNA gene homology comparison, and constructed the phylogenetic tree for Y-1. The results in- dicated that Y-1 was Paenibacillus macerans strain, and analyzed the reasons for the presence of bacteria in the rumen fluid.