An oligarchic microbial assemblage in the anoxic bottom waters of a volcanic subglacial lake. uncultured bacterium

In 2006, we sampled the anoxic bottom waters of a volcanic lake beneath the Vatnajökull ice cap (Iceland). The sample contained 5 10^5 cells/ml^-1 and whole-cell fluorescent in situ hybridization (FISH) and polymerase chain reaction with domain-specific probes showed these to be essentially all bacteria, with no detectable archaea. Pyrosequencing of the V6 hypervariable region of the 16S ribosomal RNA gene, Sanger sequencing of a clone library, and FISH-based enumeration of four major phylotypes revealed that the assemblage was dominated by a few groups of putative chemotrophic bacteria whose closest cultivated relatives use sulfide, sulfur, or hydrogen as electron donors, and oxygen, sulfate, or CO_2 as electron acceptors. Hundreds of other phylotypes are present at lower abundance in our V6 tag libraries and a rarefaction analysis indicates that sampling did not reach saturation, but FISH data limit the remaining biome to 454 sequence data is available from the Short Read Archive (SRA): SRA002254.

2006年，我们对冰岛瓦特纳冰盖（Vatnajökull）下方一座火山湖的缺氧底水开展采样工作。本次采集的样本细胞密度为5×10^5 个/毫升；通过全细胞荧光原位杂交（Fluorescent In Situ Hybridization, FISH）以及采用结构域特异性探针的聚合酶链式反应（Polymerase Chain Reaction, PCR）检测发现，样本中的微生物几乎均为细菌，未检出古菌（Archaea）。对16S核糖体RNA（16S ribosomal RNA, rRNA）基因的V6高变区进行焦磷酸测序（Pyrosequencing），对克隆文库开展桑格测序（Sanger Sequencing），并通过FISH对4种主要系统发育型（phylotype）进行计数，结果显示该微生物群落以若干类群的潜在化能营养细菌为主。这些类群的已培养近缘类群以硫化物、单质硫或氢气作为电子供体，以氧气、硫酸盐或二氧化碳作为电子受体。在我们的V6标签文库中，另有数百种系统发育型以较低丰度存在；稀疏化分析（Rarefaction Analysis）表明本次采样未达到饱和，但FISH数据限定了剩余生物群落的范围，相关454测序数据可从短读序列归档库（Short Read Archive, SRA）获取，编号为SRA002254。