title: Nitrogen fixation at 92 degrees C by a hydrothermal vent archaeon.
abstract: A methanogenic archaeon isolated from deep-sea hydrothermal vent fluid was found to reduce N(2) to NH(3) at up to 92 degrees C, which is 28 degrees C higher than the current upper temperature limit of biological nitrogen fixation. The 16S ribosomal RNA gene of the hyperthermophilic nitrogen fixer, designated FS406-22, was 99% similar to that of non-nitrogen fixing Methanocaldococcus jannaschii DSM 2661. At its optimal growth temperature of 90 degrees C, FS406-22 incorporated (15)N(2) and expressed nifH messenger RNA. This increase in the temperature limit of nitrogen fixation could reveal a broader range of conditions for life in the subseafloor biosphere and other nitrogen-limited ecosystems than previously estimated.
authors.affiliation: School of Oceanography, University of Washington, Seattle, WA 98195, USA. mausmi@alum.mit.edu
authors.forename: Mausmi P
authors.initials: MP
authors.lastname: Mehta
authors.forename: John A
authors.initials: JA
authors.lastname: Baross
mesh_terms: D000595:Amino Acid Sequence; D001105:Archaea / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism*; D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D017753:Ecosystem; D019766:Genes, Archaeal; D020459:Genes, rRNA; D019015:Geologic Sediments / Q000382:microbiology; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation / Q000235:genetics; D009591:Nitrogenase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D009876:Operon; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010140:Pacific Ocean; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012623:Seawater / Q000382:microbiology*; D018707:Volcanic Eruptions
chemical_list: D019843:Archaeal Proteins; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; D009591:Nitrogenase; C029130:nitrogenase reductase; D009584:Nitrogen