Zonation of the active methane-cycling community in deep subsurface sediments of the Peru trench

Frontiers in Microbiology

Microbiology

Mark A. Lever¹  Marc J. Alperin²  Andreas Teske²  Kai-Uwe Hinrichs³ 

[1] Department of Marine Science, Marine Science Institute, University of Texas at Austin, Port Aransas, TX, United States;Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States;Earth, Marine and Environmental Sciences, University of North Carolina at Chapel Hill, Chapel Hill, NC, United States;Organic Geochemistry Group, MARUM-Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Bremen, Germany;

关键词: deep biosphere;    methanogenesis;    anaerobic oxidation of methane;    subseafloor sediment;    ocean drilling;    methane hydrate;    carbon isotopes;    mcrA;   

DOI  :  10.3389/fmicb.2023.1192029

 received in 2023-03-22, accepted in 2023-04-24,  发布年份 2023

来源: Frontiers

【 摘 要 】

The production and anaerobic oxidation of methane (AOM) by microorganisms is widespread in organic-rich deep subseafloor sediments. Yet, the organisms that carry out these processes remain largely unknown. Here we identify members of the methane-cycling microbial community in deep subsurface, hydrate-containing sediments of the Peru Trench by targeting functional genes of the alpha subunit of methyl coenzyme M reductase (mcrA). The mcrA profile reveals a distinct community zonation that partially matches the zonation of methane oxidizing and –producing activity inferred from sulfate and methane concentrations and carbon-isotopic compositions of methane and dissolved inorganic carbon (DIC). McrA appears absent from sulfate-rich sediments that are devoid of methane, but mcrA sequences belonging to putatively methane-oxidizing ANME-1a-b occur from the zone of methane oxidation to several meters into the methanogenesis zone. A sister group of ANME-1a-b, referred to as ANME-1d, and members of putatively aceticlastic Methanothrix (formerly Methanosaeta) occur throughout the remaining methanogenesis zone. Analyses of 16S rRNA and mcrA-mRNA indicate that the methane-cycling community is alive throughout (rRNA to 230 mbsf) and active in at least parts of the sediment column (mRNA at 44 mbsf). Carbon-isotopic depletions of methane relative to DIC (−80 to −86‰) suggest mostly methane production by CO2 reduction and thus seem at odds with the widespread detection of ANME-1 and Methanothrix. We explain this apparent contradiction based on recent insights into the metabolisms of both ANME-1 and Methanothricaceae, which indicate the potential for methanogenetic growth by CO2 reduction in both groups.

【 授权许可】

Unknown   
Copyright © 2023 Lever, Alperin, Hinrichs and Teske.

【 图 表 】

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