Construction of DnaJ Database for Medically important Bacteria to determine Species Definition

细菌是通过16S rDNA基因序列变异进行系统发育分类的，该信息对未知细菌的系统发育定位特别有用，但在许多情况下，近缘物种之间的序列变异几乎相同。细菌物种在遗传学上的定义是：“物种是具有70%以上染色体相似性的菌株群体”。然而，不同的实验室测量该染色体DNA相似性的方法不同，导致同一物种群在不同实验室的相似性值不同。因此，司法委员会宣布要积累至少5种不同的饲养基因序列，这些基因序列比16SD rDNA更可变，对确定细菌种类很有用。我们专注于DnaJ序列，并收集了医学上重要的细菌群的序列。葡萄球菌、链球菌、军团菌、分枝杆菌、弧菌、气单胞菌和肠杆菌科的成员。dnaJ的序列变异大于16S rDNA。胃支原体与甘肃支原体16S rDNA序列相同，但两种菌株的型株和临床菌株差异大于4%。溶藻弧菌组和副溶血性弧菌组、霍乱弧菌组和拟弧菌组也具有相同的16S rDNA序列，但它们的dnaJ序列相差4% ~ 7%。一般来说，一个属的DnaJ变异范围在75%到100%之间。另一方面，属内16S rDNA的变异范围为90% ~ 100%。这些数据支持dnaj序列信息对物种定义和设计特定序列以在物种水平上检测细菌非常有用。

Bacteria is phylogenetically classified with 16S rDNA gene sequence variationThe information is especially useful to find phylogenetic position of unidentified bacteria, however, the sequence variation among closely related species are almost identical in many cases. Bacterial species is genetically defined as, "Species is a population of strains, which shares more than 70% chromosome similarity ". However, methods to measure this chromosome DNA similarity are different from one laboratory to another and as a result, the similarity values of same species group are different among different laboratories. So Judicial commission announced to accumulate at least 5 different house keeping gene sequences, which are more variable than 16SD rDNA and useful to determine bacterial species.We focused on DnaJ sequences and collected the sequences of medically important bacterial groups. Staphylococcus, Streptococccus, Legionella, Mycobacterium, Vibrio, Aeromonas and members of Family Enterobacteriaceae.The sequence variation of dnaJ is bigger than 16S rDNA. M. gastri and M. kansasiishares identical 16S rDNA sequence, however, type strains and clinical strains of these species were different more than 4%. Vibrio alginolyticus and Vibrio parahaemolyticus group, Vibrio cholerae and Vibrio mimicus group also shares identical 16S rDNA sequences, however, their dnaJ sequence are 4 to 7 percent different. Generally, DnaJ variation in a genus ranged from 75% to 100%,. On the Other hand, Variation of 16S rDNA within a genus ranged from 90 to 100%.These data supported that the dnaj sequence information is extremely useful to define species and also to design specific sequence to detect bacteria at species level.