Engel Annette Summers, Lee Natuschka, Porter Megan L, Stern Libby A, Bennett Philip C, Wagner Michael
Research Group for Microbial Geochemistry, Department of Geological Sciences, University of Texas at Austin, Austin, Texas 78712, USA.
Appl Environ Microbiol. 2003 Sep;69(9):5503-11. doi: 10.1128/AEM.69.9.5503-5511.2003.
Hydrogen sulfide-rich groundwater discharges from springs into Lower Kane Cave, Wyoming, where microbial mats dominated by filamentous morphotypes are found. The full-cycle rRNA approach, including 16S rRNA gene retrieval and fluorescence in situ hybridization (FISH), was used to identify these filaments. The majority of the obtained 16S rRNA gene clones from the mats were affiliated with the "Epsilonproteobacteria" and formed two distinct clusters, designated LKC group I and LKC group II, within this class. Group I was closely related to uncultured environmental clones from petroleum-contaminated groundwater, sulfidic springs, and sulfidic caves (97 to 99% sequence similarity), while group II formed a novel clade moderately related to deep-sea hydrothermal vent symbionts (90 to 94% sequence similarity). FISH with newly designed probes for both groups specifically stained filamentous bacteria within the mats. FISH-based quantification of the two filament groups in six different microbial mat samples from Lower Kane Cave showed that LKC group II dominated five of the six mat communities. This study further expands our perceptions of the diversity and geographic distribution of "Epsilonproteobacteria" in extreme environments and demonstrates their biogeochemical importance in subterranean ecosystems.
富含硫化氢的地下水从泉水中排入怀俄明州的下凯恩洞穴，在那里发现了以丝状形态类型为主的微生物垫。采用全周期rRNA方法，包括16S rRNA基因检索和荧光原位杂交（FISH）来鉴定这些丝状菌。从微生物垫中获得的大多数16S rRNA基因克隆隶属于“ε-变形菌纲”，并在该纲内形成了两个不同的簇，分别命名为LKC第一组和LKC第二组。第一组与来自石油污染地下水、硫化泉和硫化洞穴的未培养环境克隆密切相关（序列相似性为97%至99%），而第二组形成了一个与深海热液喷口共生体中度相关的新分支（序列相似性为90%至94%）。用新设计的针对这两组的探针进行FISH，特异性地对微生物垫内的丝状细菌进行了染色。对来自下凯恩洞穴的六个不同微生物垫样本中的两个丝状菌群进行基于FISH的定量分析，结果表明在六个垫群落中的五个中，LKC第二组占主导地位。这项研究进一步拓展了我们对极端环境中“ε-变形菌纲”多样性和地理分布的认识，并证明了它们在地下生态系统中的生物地球化学重要性。
