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Comparative ecology of H2 cycling in sedimentary and phototrophic ecosystemsThe simple biochemistry of H2 is critical to a large number of microbial processes, affecting the interaction of organisms with each other and with the environment. The sensitivity of each of these processes to H2 can be described collectively, through the quantitative language of thermodynamics. A necessary prerequisite is to understand the factors that, in turn, control H2 partial pressures. These factors are assessed for two distinctly different ecosystems. In anoxic sediments from Cape Lookout Bight (North Carolina, USA), H2 partial pressures are strictly maintained at low, steady-state levels by H2-consuming organisms, in a fashion that can be quantitatively predicted by simple thermodynamic calculations. In phototrophic microbial mats from Baja California (Mexico), H2 partial pressures are controlled by the activity of light-sensitive H2-producing organisms, and consequently fluctuate over orders of magnitude on a daily basis. The differences in H2 cycling can subsequently impact any of the H2-sensitive microbial processes in these systems. In one example, methanogenesis in Cape Lookout Bight sediments is completely suppressed through the efficient consumption of H2 by sulfate-reducing bacteria; in contrast, elevated levels of H2 prevail in the producer-controlled phototrophic system, and methanogenesis occurs readily in the presence of 40 mM sulfate.
Document ID
20040087973
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hoehler, Tori M.
(NASA Ames Research Center Moffett Field CA United States)
Albert, Daniel B.
Alperin, Marc J.
Bebout, Brad M.
Martens, Christopher S.
Des Marais, David J.
Date Acquired
August 21, 2013
Publication Date
August 1, 2002
Publication Information
Publication: Antonie van Leeuwenhoek
Volume: 81
Issue: 1-4
ISSN: 0003-6072
Subject Category
Life Sciences (General)
Distribution Limits
Public
Copyright
Other
Keywords
Review, Tutorial
Review

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