Hydrogen utilization potential in subsurface sediments

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    Rishi Ram Adhikari, MARUM / University of Bremen, GermanyClemens Glombitza, Julia Nickel, GFZ German Research Centre for Geosciences, Potsdam, Institute of Earth and Environmental Science, University of Potsdam, Germany, GermanyChloe H. Anderson, Department of Earth and Environment, Boston University, Boston, MA, USA, United StatesAnn G. Dunlea, Department of Earth and Environment, Boston University, Boston, MA, USA, United StatesArthur J. Spivack, Graduate School of Oceanography, University of Rhode Island, Kingston, RI, USA, United StatesRichard W. Murray, Department of Earth and Environment, Boston University, Boston, MA, USA, United StatesSteven D'Hondt, Graduate School of Oceanography, University of Rhode Island, Narragansett, RI, United StatesJens Kallmeyer, Deutsches GeoForschungsZentrum GFZ, Telegrafenberg, Potsdam, Germany., Germany
Subsurface microbial communities undertake many terminal electron-accepting processes, often simultaneously. Using a tritium-based assay, we measured the potential hydrogen oxidation catalyzed by hydrogenase enzymes in several subsurface sedimentary environments (Lake Van, Barents Sea, Equatorial Pacific, and Gulf of Mexico) with different predominant electron-acceptors. Hydrogenases constitute a diverse family of enzymes expressed by microorganisms that utilize molecular hydrogen as a metabolic substrate, product, or intermediate. The assay reveals the potential for utilizing molecular hydrogen and allows qualitative detection of microbial activity irrespective of the predominant electron-accepting process. Because the method only requires samples frozen immediately after recovery, the assay can be used for identifying microbial activity in subsurface ecosystems without the need to preserve live material. We measured potential hydrogen oxidation rates in all samples from multiple depths at several sites that collectively span a wide range of environmental conditions and biogeochemical zones. Potential activity normalized to total cell abundance ranges over five orders of magnitude and varies, dependent upon the predominant terminal electron acceptor. Lowest per-cell potential rates characterize the zone of nitrate reduction and highest per-cell potential rates occur in the methanogenic zone. Possible reasons for this relationship to predominant electron acceptor include (i) increasing importance of fermentation in successively deeper biogeochemical zones and (ii) adaptation of H2ases to successively higher concentrations of H2 in successively deeper zones.
Original languageEnglish
Article number8
JournalFrontiers in Microbiology
StatePublished - 26 Jan 2016

    Research areas

  • hydrogenase, tritium assay, deep biosphere, microbial activity, Lake Van, Barents Sea, Equatorial Pacific, Gulf of Mexico

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