Kroer Paul, Kjeldsen Kasper U, Nyengaard Jens R, Schramm Andreas, Funch Peter
Section for Genetics, Ecology, and Evolution, Department of Bioscience, Aarhus University Aarhus, Denmark.
Section for Microbiology and Center for Geomicrobiology, Department of Bioscience, Aarhus University Aarhus, Denmark.
Front Microbiol. 2016 Apr 26;7:539. doi: 10.3389/fmicb.2016.00539. eCollection 2016.
Priapulus caudatus (phylum Priapulida) is a benthic marine predatory worm with a cosmopolitan distribution. In its digestive tract we detected symbiotic bacteria that were consistently present in specimens collected over 8 years from three sites at the Swedish west coast. Based on their 16S rRNA gene sequence, these symbionts comprise a novel genus of the order Rickettsiales (Alphaproteobacteria). Electron microscopy and fluorescence in situ hybridization (FISH) identified them as extracellular, elongate bacteria closely associated with the microvilli, for which we propose the name "Candidatus Tenuibacter priapulorum". Within Rickettsiales, they form a phylogenetically well-defined, family-level clade with uncultured symbionts of marine, terrestrial, and freshwater arthropods. Cand. Tenuibacter priapulorum expands the host range of this candidate family from Arthropoda to the entire Ecdysozoa, which may indicate an evolutionary adaptation of this bacterial group to the microvilli-lined guts of the Ecdysozoa.
尾鳃蚓（鳃曳动物门）是一种底栖海洋捕食性蠕虫，分布于世界各地。在其消化道中，我们检测到了共生细菌，这些细菌在8年多的时间里，一直存在于从瑞典西海岸三个地点采集的样本中。基于它们的16S rRNA基因序列，这些共生菌属于立克次氏体目（α-变形菌纲）中的一个新属。电子显微镜和荧光原位杂交（FISH）鉴定它们为与微绒毛紧密相关的细胞外细长细菌，我们将其命名为“暂定纤细普氏杆菌（Candidatus Tenuibacter priapulorum）”。在立克次氏体目中，它们与海洋、陆地和淡水节肢动物的未培养共生菌形成了一个系统发育明确的科级分支。暂定纤细普氏杆菌将这个候选科的宿主范围从节肢动物扩展到了整个蜕皮动物，这可能表明该细菌类群对蜕皮动物微绒毛内衬肠道的进化适应。
