芽胞杆菌型益生菌YK-1R的分子分类及系统发育地位的研究

MOLECULAR IDENTIFICATION AND PHYLOGENIC CHARACTERIZATION OF A PROBIOTIC BACILLUS STRAIN YK-1R BASED ON 16S rRNA GENE

目的 :对具有良好益生作用的芽胞杆菌YK 1R菌株的分类地位及其与Bacillus属细菌的系统进化关系进行研究 ,为对益生素产品进行质量控制和设计专一性探索对此菌进行种群动态监测提供依据。方法 :1 6SrDNA近全序列PCR扩增、克隆和测序 ,再对其序列在RibosomalDatabaseProjectⅡ中进行比较鉴定 ,然后用此序列与GenBank中Bacillus属其他 53种菌的 1 6SrDNA进行系统进化关系比较 ,最后用特异性引物扩增Bacillussubtilis相关菌的 60 0bp的特征序列。结果 :YK 1R的序列在RDP中与Bacillussubtilis的同源性在 98%以上。系统进化关系分析得到有 5个分支的无根进化树 ,YK 1R属于Bacillussubtilis为代表的一支。此菌株也带有Bacillussubtilis相关菌的 60 0bp的特征序列。结论 :YK 1R应为Bacillussubtilis种内的一个菌株 。

Objective:To provide an experimental foundation for developing molecular method to inspect the probiotic product quality and for designing a specific probe to monitor the population dynamics of a Bacillus probiotic strain YK 1R in animal intestine based on 16S rRNA genes.Methods:The nearly full length 16S rDNA of YK 1R was amplified by using universal eubacterial primers and the product was cloned and sequenced.Results:Similarity searching against Ribosomal Database Project Ⅱ indicated that the strain shared a 98% homology with Bacillus subtilis An unrooted tree was built based on the alignment of 16S rDNA sequences of YK 1R and other 53 Bacillus species.All the sequences were divided into five different branches with YK 1R falling into the Bacillus subtilis group.A signature sequence of Bacillus subtilis group was also amplified in the strain with specific primers.Conclusion:YK 1R was identified as a strain in Bacillus subtilis, the same conclusion as of bacteriological identification