Affiliation:
1. School of Oceanography
2. Joint Institute for the Study of Atmosphere and Ocean, University of Washington, Seattle, Washington 98195
Abstract
ABSTRACT
The subseafloor microbial habitat associated with typical unsedimented mid-ocean-ridge hydrothermal vent ecosystems may be limited by the availability of fixed nitrogen, inferred by the low ammonium and nitrate concentrations measured in diffuse hydrothermal fluid. Dissolved N
2
gas, the largest reservoir of nitrogen in the ocean, is abundant in deep-sea and hydrothermal vent fluid. In order to test the hypothesis that biological nitrogen fixation plays an important role in nitrogen cycling in the subseafloor associated with unsedimented hydrothermal vents, degenerate PCR primers were designed to amplify the nitrogenase iron protein gene
nifH
from hydrothermal vent fluid. A total of 120
nifH
sequences were obtained from four samples: a nitrogen-poor diffuse vent named marker 33 on Axial Volcano, sampled twice over a period of 1 year as its temperature decreased; a nitrogen-rich diffuse vent near Puffer on Endeavour Segment; and deep seawater with no detectable hydrothermal plume signal. Subseafloor
nifH
genes from marker 33 and Puffer are related to anaerobic clostridia and sulfate reducers. Other
nifH
genes unique to the vent samples include proteobacteria and divergent
Archaea
. All of the
nifH
genes from the deep-seawater sample are most closely related to the thermophilic, anaerobic archaeon
Methanococcus thermolithotrophicus
(77 to 83% amino acid similarity). These results provide the first genetic evidence of potential nitrogen fixers in hydrothermal vent environments and indicate that at least two sources contribute to the diverse assemblage of
nifH
genes detected in hydrothermal vent fluid:
nifH
genes from an anaerobic, hot subseafloor and
nifH
genes from cold, oxygenated deep seawater.
Publisher
American Society for Microbiology
Subject
Ecology,Applied Microbiology and Biotechnology,Food Science,Biotechnology
Reference81 articles.
1. Affourtit, J., J. P. Zehr, and H. W. Paerl. 2001. Distribution of nitrogen-fixing microorganisms along the Neuse River Estuary, North Carolina. Microb. Ecol.41:114-123.
2. Gapped BLAST and PSI-BLAST: a new generation of protein database search programs
3. Bagwell, C. E., J. R. La Rocque, G. W. Smith, S. W. Polson, M. J. Friez, J. W. Longshore, and C. R. Lovell. 2002. Molecular diversity of diazotrophs in oligotrophic tropical seagrass bed communities. FEMS Microbiol. Ecol.39:113-119.
4. Baker, E. T., C. G. Fox, and J. P. Cowen. 1999. In situ observations of the onset of hydrothermal discharge during the 1998 submarine eruption of Axial Volcano, Juan de Fuca Ridge. Geophys. Res. Lett.26:3445-3448.
5. Baross J. A. 1998. Do the geological and geochemical records of the early earth support the prediction from global phylogenetic models of a thermophilic cenancestor? p. 3-18. In J. Wiegel and M. W. W. Adams (ed.) Thermophiles: the keys to molecular evolution and the origin of life? Taylor and Francis Inc. Philadelphia Pa.
Cited by
167 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献