应用系统发育分析方法鉴别近缘病原菌

目的:以gyrB基因序列为基础,采用系统发育分析方法构建进化树,对种系关系密切的病原菌进行区分鉴别。方法:测序获得本地区19株大肠埃希菌、13株志贺菌、2株豚鼠气单胞菌、2株嗜水气单胞菌、1株维隆气单胞菌的gyrB基因序列,并将其同公共数据库已有序列合并,构建进化树。分析各序列在树中的聚类关系,以此对菌株进行种水平分类鉴别,并同BLA ST查询结果相比较。结果:除鲍氏和痢疾志贺菌外,对检测的所有序列,在进化树上与之最邻近的5条序列均为该种菌株。而对一部分菌株,其BLA ST查询结果中含有其它菌种的或分类关系不明确的序列。结论:以系统发育方法对种系发生关系密切的病原菌序列进行鉴别,具有较好的分辨力和准确度。

Identification of closely related bacteria via phylogenetic methods

Objective: To differentiate closely related pathogenic bacteria via phylogenetic method on the basis of gyrB gene sequences.Methods: GyrB sequences of 19 strains of E.coli,13 Shigella spp.,2 Aeromonas caviae,2 Aeromonas hydrophilia,1 Aeromonas veronii were determined and combined with sequences retrieved from public databases to construct phylogenetic trees.For each sequence tested,the identification deduced from the clustering relation of sequences was compared with the phenetic identification.Results: All the tested sequences,except those of Shigella boydii and Shigella dysenteriae,were corresponded with the 5 closest sequences on the tree at the species level.While the BLAST queries returned some other bacteria organisms or undetermined entries.Conclusion: Phylogenetics displays good discriminative power in bacterial sequences differentiation.