House, Christopher H. and Beal, Emily J. and Orphan, Victoria J. (2011) The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy. Life, 1 (1). pp. 19-33. ISSN 2075-1729. PMCID PMC4187123. http://resolver.caltech.edu/CaltechAUTHORS:20141113-095602878
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On Earth, marine anaerobic methane oxidation (AOM) can be driven by the microbial reduction of sulfate, iron, and manganese. Here, we have further characterized marine sediment incubations to determine if the mineral dependent methane oxidation involves similar microorganisms to those found for sulfate-dependent methane oxidation. Through FISH and FISH-SIMS analyses using ^(13)C and ^(15)N labeled substrates, we find that the most active cells during manganese dependent AOM are primarily mixed and mixed-cluster aggregates of archaea and bacteria. Overall, our control experiment using sulfate showed two active bacterial clusters, two active shell aggregates, one active mixed aggregate, and an active archaeal sarcina, the last of which appeared to take up methane in the absence of a closely-associated bacterial partner. A single example of a shell aggregate appeared to be active in the manganese incubation, along with three mixed aggregates and an archaeal sarcina. These results suggest that the microorganisms (e.g., ANME-2) found active in the manganese-dependent incubations are likely capable of sulfate-dependent AOM. Similar metabolic flexibility for Martian methanotrophs would mean that the same microbial groups could inhabit a diverse set of Martian mineralogical crustal environments. The recently discovered seasonal Martian plumes of methane outgassing could be coupled to the reduction of abundant surface sulfates and extensive metal oxides, providing a feasible metabolism for present and past Mars. In an optimistic scenario Martian methanotrophy consumes much of the periodic methane released supporting on the order of 10,000 microbial cells per cm2 of Martian surface. Alternatively, most of the methane released each year could be oxidized through an abiotic process requiring biological methane oxidation to be more limited. If under this scenario, 1% of this methane flux were oxidized by biology in surface soils or in subsurface aquifers (prior to release), a total of about 10^(20) microbial cells could be supported through methanotrophy with the cells concentrated in regions of methane release.
|Additional Information:||© 2011 by the authors; licensee MDPI, Basel, Switzerland. This article is an open-access article distributed under the terms and conditions of the Creative Commons Attribution license (http://creativecommons.org/licenses/by/3.0/). Received: 25 August 2011; in revised form: 14 September 2011; Accepted: 11 November 2011; Published: 18 November 2011. We thank three anonymous reviewers for very useful comments, suggestions, and critics, as well as A. Dekas, A. Green-Saxena, A. Schmitt and Z. Zhang for technical assistance. We also thank the shipboard scientists, crew and pilots of R ⁄ V Atlantis. Funding for this project has come from the National Science Foundation (MCB-0348492), National Aeronautics and Space Administration (NASA) Astrobiology Institute under NASA–Ames Cooperative Agreement NNA04CC06A, Department of Energy (DE-SC0004949), and the Penn State Biogeochemical Research Initiative for Education (BRIE) funded by NSF (IGERT) Grant DGE-9972759.The UCLA ion Microprobe is partially supported by a grant from the National Science Foundation Instrumentation and Facilities Program.|
|PubMed Central ID:||PMC4187123|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||13 Nov 2014 19:42|
|Last Modified:||09 Jan 2016 03:40|
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