Peer-reviewed articles

An oligarchic microbial assembly in the anoxic bottom waters of a volcanic subglacial lake

Authors: Eric Gaidos, Viggo Marteinsson, Thorsteinn Thorsteinsson, Tomas Jóhannesson, Árni Rafn Rúnarsson, Andri Stefansson, Brian Glazer, Brian Lanoil, Mark Skidmore, Sukkyun Han, Mary Miller, Antje Rusch, Wilson Foo

Version: ISME Journal (International Society for Microbial Ecology)

Publication year: 2009

Summary:

In 2006, we sampled the anoxic bottom waters of a volcanic lake beneath the Vatnajökull ice cap (Iceland). The sample contained 5 × 105 cells per ml, and whole-cell fluorescent in situ hybridization (FISH) and PCR 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 assembly 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 CO2 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 <10–20% of all cells. The composition of this oligarchy can be understood in the context of the chemical disequilibrium created by the mixing of sulfidic lake water and oxygenated glacial meltwater.

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