一株西藏牦牛源格氏乳球菌的分离鉴定

Isolation and Identification of a Strain of Lactococcus garvieae from Xizang Yaks

为了弄清引起西藏牦牛乳腺炎的病原,采集患有乳腺炎的牦牛乳汁样品进行细菌培养,将分离到的1株细菌命名为XZ-1并进行染色镜检和16S rRNA基因扩增、比对,从GenBank上下载相似性最高细菌的16S rRNA基因,采用DNA Star软件进行同源性和遗传进化分析。结果显示,分离株细菌革兰氏染色,镜检为阳性,散在或成双或短链排列的球状菌;16S rRNA基因比对表明,与GenBank中格氏乳球菌的相似性达到99.43%~99.93%,与格氏乳球菌参考株的同源性为99.5%~100%;遗传进化分析表明,西藏分离株XZ-1与格氏乳球菌参考株形成一个大的分支,且与格氏乳球菌SCH和MS4-2参考株亲缘关系较近,聚为一簇。研究表明,该分离株为格氏乳球菌,是引起乳腺炎的病原之一,为今后开展牦牛乳腺炎病原及格氏乳球菌的研究提供参考依据。

In order to clarify the pathogen causing mastitis in Xizang yaks,milk samples of yak with mastitis were collect for bacterial culture.A strain of bacteria isolated was named as XZ-1,and staining microscopy,and 16S rRNA gene amplification and comparison.The 16S rRNA gene of the most similar bacteria was download from GenBank.DNA Star software was used to analyze homology and genetic evolution.The results showed that the isolated strains of bacteria was positive,scattered or arranged in pairs or short chains of spherical bacteria by Gram-stained and microscopic examination.The 16S rRNA gene comparison showed that it had a similarity of 99.43%to 99.93%with Lactococcus garvieae in GenBank,and a simi-larity of 99.5%to 100%with the reference strain of Lactococcus garvieae.Genetic evolution analysis showed that the Xizang isolate strain XZ-1 formed a large branch with the reference strain of Lactococcus garvieae,and was closely related to the reference strains of Lactococcus garvieae SCH and MS4-2,forming a cluster.Studies have shown that this isolated strain is Lactococcus garvieae and is one of the pathogens causing mastitis,which provided a reference basis for future research on the pathogen of yak mastitis and Lactococcus garvieae.