Identification of the strain 1012 isolated from the sample of EQA of the Chinese National Center of Clinical Laboratory, and phylogenetic analysis of Actinomyces turicensisand related bacteria in the family Actinomycetaceae

Abstract

Objectives To identified the strain 1012 from the National Center of Clinical Laboratory of China for microbe inter-laboratory quality assessment in 2010, and study the taxonomic status of strain 1012 and related species in the genus Actinomyces. Methods The bacterial traditional morphological characteristics, commercial API systems, and 16S rRNA gene sequence analysis were applied to identify the problematic culture of strain 1012. The phylogenetic tree based on the remote information of the prokaryotes systems was constructed to study the taxonomic status and evolutionary relationship of the genus Actinomyces and related species in the family Actinomycetaceae. Results Strain 1012 was determined as a kind of facuhative anaerobic, non-spot-forming, Gram-positive coryneform bacteria, which was identified to Actinomyces turicensis for the phenotypic biochemical characteristics of more than 60 items, The comparative study of 16S rRNA gene showed the strain 1012 with 99. 8％ similarities to Actinomyces turicensis, but only 90. 6％ to the type species of Actinomyces bovis in the genus Actinomyces. However, the comparative study of 16S rRNA gene showed the strain 1012 with only 90. 6％ homology to the type species of Actinomyces bovis in the genus Actinomyces. Further phylogenetic analysis showed that nine independent clusters were grouped in the family Actinomycetaceae, of which four clusters were separately represented the genera Varibaculum,Mobiluncus, Actinobaculum and Arcanobacterium, while other five clusters all were designated to the genus Actinomyces. The study showed strain 1012 was located in genus Ⅲ of Actinomyces, yet with a relatively long genetic distance to Actinomyces bovis. Conclusion The genus Actinomyces may be reclassified as one genus Actinomyces sensu stricto and several new genera for the genotypic characteristics. Key words: Actinomycetaceae; RNA, ribosomal, 16S; Sequence analysis, RNA; Evaluation studies