In:
Frontiers in Microbiology, Frontiers Media SA, Vol. 14 ( 2023-5-12)
Abstract:
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). Mcr A appears absent from sulfate-rich sediments that are devoid of methane, but mcr A 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 mcr A-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 CO 2 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 CO 2 reduction in both groups.
Type of Medium:
Online Resource
ISSN:
1664-302X
DOI:
10.3389/fmicb.2023.1192029
DOI:
10.3389/fmicb.2023.1192029.s001
Language:
Unknown
Publisher:
Frontiers Media SA
Publication Date:
2023
detail.hit.zdb_id:
2587354-4
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