Hoetzinger Matthias, Schmidt Johanna, Pitt Alexandra, Koll Ulrike, Lang Elke, Hahn Martin W
1Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria.
2Leibniz-Institute DSMZ - German Collection of Microorganisms and Cell Cultures, Inhoffenstraße 7B, D-38124 Braunschweig, Germany.
Int J Syst Evol Microbiol. 2019 Jan;69(1):203-213. doi: 10.1099/ijsem.0.003130. Epub 2018 Nov 22.
Six Polynucleobacter (Burkholderiaceae, Betaproteobacteria) strains isolated from different freshwater lakes located across Europe were taxonomically investigated. Phylogenetic analyses based on 16S rRNA gene sequences assigns all six strains to the cryptic species complex PnecC within the genus Polynucleobacter. Analyses of partial glutamine synthetase (glnA) genes suggests that all six strains belong to the species-like taxon designated F15 in previous papers. Comparative genome analyses reveal that the six strains form a genomically coherent group characterized by whole-genome average nucleotide identity (gANI) values of >98 % but separated by gANI values of <88 % from the type strains and representatives of the 16 previously described Polynucleobacter species. In phylogenetic analyses based on nucleotide sequences of 319 orthologous genes, the six strains represent a monophyletic cluster that is clearly separated from all other described species. Genome sizes of the six strains range from 1.61 to 1.83 Mbp, which is smaller than genome sizes of the majority of type strains representing previously described Polynucleobacter species. By contrast, the G+C content of the DNA of the strains is well in the range of 44.8-46.6 mol% previously found for other type strains of species affiliated with the subgroup PnecC. Variation among the six strains representing the new species is evident in a number of traits. These include gene content differences, for instance regarding a gene cluster encoding anoxygenic photosynthesis, as well as phenotypic traits. We propose to name the new species represented by the six strains Polynucleobacter paneuropaeus sp. nov. and designate strain MG-25-Pas1-D2 (=DSM 103454 =CIP 111323) as the type strain.
对从欧洲各地不同淡水湖分离出的6株多核杆菌（伯克霍尔德菌科，β-变形菌纲）菌株进行了分类学研究。基于16S rRNA基因序列的系统发育分析将所有6株菌株归入多核杆菌属内的隐秘种复合体PnecC。对部分谷氨酰胺合成酶（glnA）基因的分析表明，所有6株菌株均属于先前论文中指定的类物种分类单元F15。比较基因组分析表明，这6株菌株形成了一个基因组学上连贯的群体，其全基因组平均核苷酸同一性（gANI）值>98%，但与16个先前描述的多核杆菌物种的模式菌株和代表菌株的gANI值<88%而分开。在基于319个直系同源基因核苷酸序列的系统发育分析中，这6株菌株代表一个单系聚类，明显与所有其他已描述的物种分开。这6株菌株的基因组大小在1.61至1.83 Mbp之间，小于代表先前描述的多核杆菌物种的大多数模式菌株的基因组大小。相比之下，这些菌株DNA的G+C含量很好地处于先前在隶属于PnecC亚组的其他物种模式菌株中发现的44.8 - 46.6 mol%范围内。代表新物种的这6株菌株在许多特征上存在明显差异。这些差异包括基因含量差异，例如关于编码无氧光合作用的基因簇，以及表型特征。我们提议将由这6株菌株代表的新物种命名为泛欧多核杆菌（Polynucleobacter paneuropaeus sp. nov.），并指定菌株MG - 25 - Pas1 - D2（=DSM 103454 =CIP 111323）为模式菌株。
