title: An oligarchic microbial assemblage in the anoxic bottom waters of a volcanic subglacial lake.
abstract: In 2006, we sampled the anoxic bottom waters of a volcanic lake beneath the Vatnajökull ice cap (Iceland). The sample contained 5 x 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.
authors.affiliation: Department of Geology and Geophysics, University of Hawaii at Manoa, Honolulu, HI 96822, USA. gaidos@hawaii.edu
authors.forename: Eric
authors.initials: E
authors.lastname: Gaidos
authors.forename: Viggo
authors.initials: V
authors.lastname: Marteinsson
authors.forename: Thorsteinn
authors.initials: T
authors.lastname: Thorsteinsson
authors.forename: Tomas
authors.initials: T
authors.lastname: Jóhannesson
authors.forename: Arni Rafn
authors.initials: AR
authors.lastname: Rúnarsson
authors.forename: Andri
authors.initials: A
authors.lastname: Stefansson
authors.forename: Brian
authors.initials: B
authors.lastname: Glazer
authors.forename: Brian
authors.initials: B
authors.lastname: Lanoil
authors.forename: Mark
authors.initials: M
authors.lastname: Skidmore
authors.forename: Sukkyun
authors.initials: S
authors.lastname: Han
authors.forename: Mary
authors.initials: M
authors.lastname: Miller
authors.forename: Antje
authors.initials: A
authors.lastname: Rusch
authors.forename: Wilson
authors.initials: W
authors.lastname: Foo
mesh_terms: D001105:Archaea / Q000302:isolation & purification; D001419:Bacteria / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D007055:Iceland; D008969:Molecular Sequence Data; D010802:Phylogeny; D012329:RNA, Bacterial / Q000235:genetics; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014871:Water Microbiology
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S