The Apparent Involvement of ANMEs in Mineral Dependent Methane Oxidation, as an Analog for Possible Martian Methanotrophy

Journal Article · Fri Nov 18 00:00:00 EST 2011 · Life

DOI:https://doi.org/10.3390/life1010019· OSTI ID:1629950

House, Christopher H. ^[1]; Beal, Emily J. ^[2]; Orphan, Victoria J. ^[3]

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1. Pennsylvania State Univ., University Park, PA (United States); DOE/OSTI
2. Pennsylvania State Univ., University Park, PA (United States)
3. California Institute of Technology (CalTech), Pasadena, CA (United States)

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 ¹³C and ¹⁵N 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 10²⁰ microbial cells could be supported through methanotrophy with the cells concentrated in regions of methane release.

• Research Organization: California Institute of Technology (CalTech), Pasadena, CA (United States)
• Sponsoring Organization: National Aeronautics and Space Administration (NASA); National Science Foundation (NSF); USDOE Office of Science (SC), Biological and Environmental Research (BER). Earth and Environmental Systems Science Division
• Grant/Contract Number: SC0004949
• OSTI ID: 1629950
• Journal Information: Life, Journal Name: Life Journal Issue: 1 Vol. 1; ISSN 2075-1729
• Publisher: MDPI
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
Archaea
Mars
methane
methanotrophy
subsurface biosphere