Söller R, Hirsch P, Blohm D, Labrenz M
Int J Syst Evol Microbiol. 2000 Mar;50 Pt 2:909-915. doi: 10.1099/00207713-50-2-909.
The 16S-23S rDNA internal transcribed spacer (ITS) of Roseobacter denitrificans, Roseobacter litoralis, Ruegeria algicola and strains of the recently described species Antarctobacter heliothermus and Roseovarius tolerans were analysed in order to examine DNA sequence variations and to draw conclusions about inter- and intraspecific relationships. A. heliothermus included four strains with an ITS fragment length of 1092 bp. Roseovarius tolerans was described on the basis of eight strains. Five of these harboured two ITS fragments of different lengths (959 and about 1100 bp), while the others had one fragment of either 1083 bp (two strains) or 1165 bp (one strain). ITS lengths of the related species Roseobacter denitrificans, Roseobacter litoralis and Ruegeria algicola were found to be 980, 984 and 1158 bp, respectively. Phylogenetic analyses of the DNA sequences allowed species affiliation of strains with sequence length differences of > 200 bp and recognition of relationships based on a well-supported ITS tree. The strains of A. heliothermus and Roseovarius tolerans each formed a monophyletic branch and they were separated from each other by Ruegeria algicola. This species was now clearly separated from Roseobacter denitrificans and Roseobacter litoralis, which corresponded to the new genus affiliation of Ruegeria algicola. These data were additionally supported by analyses of the structure, relative position and order of genes for tRNA(Ile) and tRNA(Ala) found within the ITS of each strain. Comparative DNA sequence analyses of ITS and 16S rDNA revealed limitations, on species and strain levels, with respect to the phylogenetic resolution of the 16S rDNA due to the limited number of informative (variable) sites, while ITS sequence analyses provided more variable and sufficiently conserved positions to discriminate between strains and to reconstruct their taxonomic relationships.
对反硝化玫瑰杆菌、滨岸玫瑰杆菌、嗜藻鲁杰氏菌以及最近描述的物种嗜热南极杆菌和耐盐玫瑰色菌的菌株的16S - 23S rDNA内部转录间隔区（ITS）进行了分析，以检测DNA序列变异，并得出关于种间和种内关系的结论。嗜热南极杆菌包括四个菌株，其ITS片段长度为1092 bp。耐盐玫瑰色菌是基于八个菌株描述的。其中五个菌株含有两个不同长度的ITS片段（959和约1100 bp），而其他菌株有一个1083 bp（两个菌株）或1165 bp（一个菌株）的片段。发现相关物种反硝化玫瑰杆菌、滨岸玫瑰杆菌和嗜藻鲁杰氏菌的ITS长度分别为980、984和1158 bp。对DNA序列的系统发育分析允许对序列长度差异大于200 bp的菌株进行物种归属，并基于得到充分支持的ITS树识别关系。嗜热南极杆菌和耐盐玫瑰色菌的菌株各自形成一个单系分支，它们被嗜藻鲁杰氏菌彼此分开。该物种现在与反硝化玫瑰杆菌和滨岸玫瑰杆菌明显分开，这与嗜藻鲁杰氏菌的新属归属相对应。这些数据还得到了对每个菌株ITS内发现的tRNA（Ile）和tRNA（Ala）基因的结构、相对位置和顺序分析的支持。ITS和16S rDNA的比较DNA序列分析揭示了，由于信息（可变）位点数量有限，在物种和菌株水平上16S rDNA系统发育分辨率存在局限性，而ITS序列分析提供了更多可变且足够保守的位置，以区分菌株并重建它们的分类关系。
