一株益生芽孢菌株的分子鉴定及其药敏分析

从健康土鸡盲肠中筛选出具有益生潜力的菌株Y31,利用细菌16SrDNA通用引物对其16SrRNA进行PCR扩增,得到1460bp的片段,该PCR产物序列通过Blast软件在NCBI网站中进行同源性比较,通过Mega3.1软件绘制系统发育树;同时,选择兽医临床上常用的15种抗生素,对菌株Y31进行药敏试验。结果表明,菌株Y31的16SrRNA序列与枯草芽孢杆菌(Bacillus subtilis)的16SrRNA序列的相似性为99.6%,在系统发育树中,它们在同一分支,且遗传距离最短,确定菌株Y31为枯草芽孢杆菌;Y31菌株对氨苄西林、青霉素及诺氟沙星有很强的耐药性,对链霉素中度敏感,而对试验中的其它抗生素高度敏感。

Molecular Identification of a Probiotic Bacillus Strain and Analysis of Drug Sensitivity

A 1460bp fragment of 16S ribosomal RNA was obtained from total DNA of strain Y31 isolated from chicken intestine by PCR amplification,using the universal primer of bacterial 16S ribosome DNA.Sequence analysis was carried out by Blast and ClustalX on NCBI website and the phylogenetic tree was constructed by Mega3.1 software.Strain Y31 was tested with 15 styles of commonly-used antibiotics veterinary clinic for drug sensitivity.The results showed that Strain Y31 shared 99.6% 16S ribosomal RNA sequence homology with Bacillus subtilis,and they were in the same branch of the phylogenetic tree and their genetic distance was the shortest.Strain Y31 was identified as Bacillus subtilis.Y31 is strongly drug-resistant to penicillin,ampicillin and norfloxacin,middle sensitive to streptomycin,and very sensitive to others.