Palmer Marike, Steenkamp Emma T, Coetzee Martin P A, Avontuur Juanita R, Chan Wai-Yin, van Zyl Elritha, Blom Jochen, Venter Stephanus N
Department of Microbiology and Plant Pathology, University of Pretoria, Pretoria, South Africa.
DST-NRF Centre of Excellence in Tree Health Biotechnology (CTHB) and Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Pretoria, South Africa.
Int J Syst Evol Microbiol. 2018 Apr;68(4):1396-1407. doi: 10.1099/ijsem.0.002540. Epub 2018 Feb 27.
The Erwiniaceae contain many species of agricultural and clinical importance. Although relationships among most of the genera in this family are relatively well resolved, the phylogenetic placement of several taxa remains ambiguous. In this study, we aimed to address these uncertainties by using a combination of phylogenetic and genomic approaches. Our multilocus sequence analysis and genome-based maximum-likelihood phylogenies revealed that the arsenate-reducing strain IMH and plant-associated strain ATCC 700886, both previously presumptively identified as members of Pantoea, represent novel species of Erwinia. Our data also showed that the taxonomy of Erwinia teleogrylli requires revision as it is clearly excluded from Erwinia and the other genera of the family. Most strikingly, however, five species of Pantoea formed a distinct clade within the Erwiniaceae, where it had a sister group relationship with the Pantoea + Tatumella clade. By making use of gene content comparisons, this new clade is further predicted to encode a range of characters that it shares with or distinguishes it from related genera. We thus propose recognition of this clade as a distinct genus and suggest the name Mixta in reference to the diverse habitats from which its species were obtained, including plants, humans and food products. Accordingly, a description for Mixta gen. nov. is provided to accommodate the four species Mixta calida comb. nov., M. gaviniae comb. nov., M. intestinalis comb. nov. and M. theicola comb. nov., with M. calida as the type species for the genus.
欧文氏菌科包含许多具有农业和临床重要性的物种。尽管该科中大多数属之间的关系相对明确，但几个分类单元的系统发育位置仍不明确。在本研究中，我们旨在通过结合系统发育和基因组方法来解决这些不确定性。我们的多位点序列分析和基于基因组的最大似然系统发育分析表明，先前被假定为泛菌属成员的砷酸盐还原菌株IMH和植物相关菌株ATCC 700886代表欧文氏菌属的新物种。我们的数据还表明，稻虱欧文氏菌的分类需要修订，因为它显然被排除在欧文氏菌属和该科的其他属之外。然而，最引人注目的是，泛菌属的五个物种在欧文氏菌科中形成了一个独特的分支，与泛菌属+塔特姆菌属分支具有姐妹群关系。通过基因含量比较，进一步预测这个新分支编码一系列与相关属共享或区分的特征。因此，我们建议将这个分支识别为一个独特的属，并建议使用Mixta这个名称，以参考其物种所来自的不同栖息地，包括植物、人类和食品。相应地，提供了Mixta gen. nov.的描述，以容纳四个物种，即Mixta calida comb. nov.、M. gaviniae comb. nov.、M. intestinalis comb. nov.和M. theicola comb. nov.，其中M. calida为该属的模式种。
