Division of Microbial Ecology, Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria.
Institute of Specific Prophylaxis and Tropical Medicine, Medical University of Vienna, Vienna, Austria.
Sci Rep. 2017 Jun 13;7(1):3394. doi: 10.1038/s41598-017-03642-8.
Free-living amoebae are well known for their role in controlling microbial community composition through grazing, but some groups, namely Acanthamoeba species, also frequently serve as hosts for bacterial symbionts. Here we report the first identification of a bacterial symbiont in the testate amoeba Cochliopodium. The amoeba was isolated from a cooling tower water sample and identified as C. minus. Fluorescence in situ hybridization and transmission electron microscopy revealed intracellular symbionts located in vacuoles. 16S rRNA-based phylogenetic analysis identified the endosymbiont as member of a monophyletic group within the family Coxiellaceae (Gammaprotebacteria; Legionellales), only moderately related to known amoeba symbionts. We propose to tentatively classify these bacteria as 'Candidatus Cochliophilus cryoturris'. Our findings add both, a novel group of amoeba and a novel group of symbionts, to the growing list of bacteria-amoeba relationships.
自由生活的阿米巴原虫通过吞噬作用控制微生物群落组成而广为人知，但有些群体，如棘阿米巴属物种，也经常作为细菌共生体的宿主。在这里，我们首次报道了在有壳变形虫 Cochliopodium 中发现细菌共生体。该阿米巴原虫从冷却塔水样中分离出来，被鉴定为 C. minus。荧光原位杂交和透射电子显微镜显示，位于空泡内的共生体。基于 16S rRNA 的系统发育分析将内共生体鉴定为科克斯利菌科（γ变形菌纲；军团菌目）内一个单系群的成员，与已知的阿米巴共生体仅有中度亲缘关系。我们建议将这些细菌暂时归类为“Candidatus Cochliophilus cryoturris”。我们的发现增加了一个新的阿米巴群体和一个新的共生体群体，使细菌-阿米巴关系的不断增长的列表更加丰富。
