Rameshkumar N, Fukui Youhei, Sawabe Tomoo, Nair Sudha
Microbiology Department, M. S. Swaminathan Research Foundation, 3rd Cross Street, Taramani Institutional Area, Chennai - 600 113, India.
Int J Syst Evol Microbiol. 2008 Jul;58(Pt 7):1608-15. doi: 10.1099/ijs.0.65604-0.
Two facultatively anaerobic, nitrogen-fixing bacteria (strains MSSRF30(T) and MSSRF31) were isolated from a mangrove-associated wild rice (Porteresia coarctata Tateoka). These strains were determined to be nitrogen-fixers using the acetylene reduction assay and by PCR detection of a nifH gene amplicon. Phylogenetic analyses based on 16S rRNA gene sequences indicated that the novel strains were most closely related to Vibrio fluvialis LMG 7894(T) (96.8 % gene sequence similarity), Vibrio furnissii LMG 7910(T) (96.8 % sequence similarity) and Vibrio tubiashii CIP 102760(T) (96.7 % sequence similarity). Further multilocus sequence analysis using recA, pyrH, rpoA and nifH genes also showed low levels of sequence similarities (83-93 %) with all species of the genus Vibrio with validly published names. A multigene phylogenetic tree using concatenated sequences of the four genes (16S rRNA, rpoA, recA and pyrH) showed that strains MSSRF30(T) and MSSRF31 occupied a distinct phylogenetic position, forming a long branching that was not clustered with any other recognized Vibrio species. The fatty acid profile also suggested that the novel strains belonged to the genus Vibrio. The results of physiological and biochemical tests, genomic fingerprinting and DNA-DNA hybridization analyses clearly differentiated both novel strains from their closest phylogenetic neighbours, Vibrio cholerae IID6019, Vibrio mimicus LMG 7896(T), V. fluvialis LMG 7894(T) and V. furnissii LMG 7910(T). Several phenotypic traits enabled the differentiation of strain MSSRF30(T) from other species of the genus Vibrio. The DNA G+C content of strain MSSRF30(T) was 44.4+/-3.1 mol%. Based on genotypic, phenotypic, chemotaxonomic, phylogenetic and DNA-DNA hybridization analyses, the name Vibrio porteresiae sp. nov. (type strain MSSRF30(T)=LMG 24061(T)=DSM 19223(T)) is proposed for this novel taxon.
从一种与红树林相关的野生稻（窄叶野生稻Porteresia coarctata Tateoka）中分离出两株兼性厌氧固氮细菌（菌株MSSRF30(T)和MSSRF31）。通过乙炔还原试验和对nifH基因扩增子进行PCR检测，确定这些菌株为固氮菌。基于16S rRNA基因序列的系统发育分析表明，这些新菌株与河流弧菌Vibrio fluvialis LMG 7894(T)（基因序列相似性为96.8%）、弗氏弧菌Vibrio furnissii LMG 7910(T)（序列相似性为96.8%）和塔氏弧菌Vibrio tubiashii CIP 102760(T)（序列相似性为96.7%）关系最为密切。使用recA、pyrH、rpoA和nifH基因进行的进一步多位点序列分析也显示，与所有已有效发表名称的弧菌属物种的序列相似性较低（83 - 93%）。利用四个基因（16S rRNA、rpoA、recA和pyrH）的串联序列构建的多基因系统发育树表明，菌株MSSRF30(T)和MSSRF31占据了一个独特的系统发育位置，形成了一个长分支，未与任何其他已确认的弧菌物种聚类。脂肪酸谱也表明这些新菌株属于弧菌属。生理生化测试、基因组指纹图谱和DNA - DNA杂交分析结果清楚地将这两株新菌株与其最接近的系统发育邻株霍乱弧菌Vibrio cholerae IID6019、模仿弧菌Vibrio mimicus LMG 7896(T)、河流弧菌V. fluvialis LMG 7894(T)和弗氏弧菌V. furnissii LMG 7910(T)区分开来。几个表型特征能够将菌株MSSRF30(T)与弧菌属的其他物种区分开来。菌株MSSRF30(T) 的DNA G + C含量为44.4±3.1 mol%。基于基因型、表型、化学分类、系统发育和DNA - DNA杂交分析，为这个新分类单元提议命名为波特氏弧菌Vibrio porteresiae sp. nov.（模式菌株MSSRF30(T)=LMG 24061(T)=DSM 19223(T)）。
