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 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 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 <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.
|Number of pages||12|
|Publication status||Published - Apr 2009|
Bibliographical noteFunding Information:
This material is based upon work supported by the National Aeronautics and Space Administration through the NASA Astrobiology Institute under Cooperative Agreement no. NNA04CC08A issued through the Office of Space Science and by the Icelandic Centre for Research. The Icelandic National Energy Authority, National Power Company and Public Roads Administration provided logistical support. Members of the Icelandic Glaciological Society assisted in the field campaign on Vatnajökull. The NAI lead team at the Marine Biological Laboratory performed pyrosequencing, and Mitch Sogin, Hilary Morrison and Sue Huse assisted with procedures and analysis. Ruth Richardson provided an enrichment culture for FISH. Brian Popp and Terri Rust measured POM.
- Extreme environments
- Microbial diversity
- Sulfide oxidation