Nakagawa Yasuyoshi, Sakane Takeshi, Suzuki Makoto, Hatano Kazunori
Institute for Fermentation, Osaka, Japan.
J Gen Appl Microbiol. 2002 Jun;48(3):155-65. doi: 10.2323/jgam.48.155.
The 16S rDNA sequences of 40 strains of 17 species in the genus Flexibacter, 5 strains of 4 species in the genus Microscilla, and 1 strain of Flexithrix dorotheae, including all type strains of approved and validated species in these genera, were determined to reveal their phylogenetic relationships. The 16S rRNA sequence analysis demonstrated the extreme heterogeneity of the genera Flexibacter and Microscilla. The strains examined diverged into 24 distinct lines of descent (1 group included both flexibacteria and flexithrix, and 1 group included both flexibacteria and microscilla) that were remote from each other at the genus level or higher. Flexibacter strains were scattered across the cytophaga-flavobacteria-bacteroides phylum and divided into 20 phylogenetic groups, and the genus Microscilla was separated into 5 groups. Flexibacter flexilis, the type species of the genus Flexibacter, and Microscilla marina, the type species of the genus Microscilla, were isolated from other organisms in their respective genera. This means that each genus should be restricted to only the type species. Flexithrix dorotheae, the type species of the genus Flexithrix, clustered with Flexibacter aggregans. The heterogeneity was found not only within genera but also within species. Flexibacter aggregans, Flexibacter aurantiacus, Flexibacter flexilis, Flexibacter roseolus, Flexibacter tractuosus, and "Microscilla sericea" each contained phylogenetically distant strains. The taxonomic concept of the genera Flexibacter, Flexithrix, and Microscilla should be reorganized in accordance with the natural relationships revealed in this study.
测定了弯曲杆菌属17个种的40株菌株、微鞘菌属4个种的5株菌株以及多罗西弯曲丝菌的1株菌株的16S rDNA序列，其中包括这些属中已批准和验证物种的所有模式菌株，以揭示它们的系统发育关系。16S rRNA序列分析表明弯曲杆菌属和微鞘菌属具有极高的异质性。所检测的菌株分化为24个不同的谱系（1个组包括弯曲杆菌和弯曲丝菌，1个组包括弯曲杆菌和微鞘菌），它们在属水平或更高水平上彼此相距甚远。弯曲杆菌菌株散布在噬纤维菌-黄杆菌-拟杆菌门中，分为20个系统发育组，微鞘菌属分为5个组。弯曲杆菌属的模式种柔韧弯曲杆菌和微鞘菌属的模式种海洋微鞘菌与各自属中的其他生物分离。这意味着每个属应仅限定于模式种。弯曲丝菌属的模式种多罗西弯曲丝菌与聚集弯曲杆菌聚类。异质性不仅在属内发现，也在种内发现。聚集弯曲杆菌、橙黄弯曲杆菌、柔韧弯曲杆菌、玫瑰色弯曲杆菌、曲折弯曲杆菌和“丝质微鞘菌”各自都包含系统发育上距离较远的菌株。弯曲杆菌属、弯曲丝菌属和微鞘菌属的分类概念应根据本研究揭示的自然关系进行重新组织。
