Acetoclastic Methanosaeta area dominant methanogens in organic-rich Antarctic marine sediments

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doi: 10.1038/ismej.2017.150
Author(s): Carr, Stephanie A.; Schubotz, Florence; Dunbar, Robert B.; Mills, Christopher T.; Dias, Robert; Summons, Roger E.; Mandernack, Kevin W.
Author Affiliation(s): Primary:
Bigelow Laboratory for Ocean Sciences, East Boothbay, ME, United States
University of Bremen, Germany
Stanford University, United States
U. S. Geological Survey, United States
Massachusetts Institute of Technology, United States
Indiana University-Purdue University Indianapolis, United States
Volume Title: ISME Journal
Source: The ISME Journal, 12(2), p.330-342. Publisher: Nature Publishing Group, London, United Kingdom. ISSN: 1751-7362
Note: In English. Based on Publisher-supplied data. 63 refs.; illus.
Summary: Despite accounting for the majority of sedimentary methane, the physiology and relative abundance of subsurface methanogens remain poorly understood. We combined intact polar lipid and metagenome techniques to better constrain the presence and functions of methanogens within the highly reducing, organic-rich sediments of Antarctica's Adelie Basin. The assembly of metagenomic sequence data identified phylogenic and functional marker genes of methanogens and generated the first Methanosaeta sp. genome from a deep subsurface sedimentary environment. Based on structural and isotopic measurements, glycerol dialkyl glycerol tetraethers with diglycosyl phosphatidylglycerol head groups were classified as biomarkers for active methanogens. The stable carbon isotope (δ13C) values of these biomarkers and the Methanosaeta partial genome suggest that these organisms are acetoclastic methanogens and represent a relatively small (0.2%) but active population. Metagenomic and lipid analyses suggest that Thaumarchaeota and heterotrophic bacteria co-exist with Methanosaeta and together contribute to increasing concentrations and δ13C values of dissolved inorganic carbon with depth. This study presents the first functional insights of deep subsurface Methanosaeta organisms and highlights their role in methane production and overall carbon cycling within sedimentary environments.
Year of Publication: 2018
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 07 Marine Geology and Oceanography; Adelie Basin; Adelie Coast; Aliphatic hydrocarbons; Alkanes; Antarctica; Bacteria; Biochemistry; Biomarkers; C-13/C-12; Carbon; Hydrocarbons; Integrated Ocean Drilling Program; Isotope ratios; Isotopes; Lipids; Marine sediments; Methane; Methanosaeta; Organic compounds; Sediments; Southern Ocean; Stable isotopes; Wilkes Land
Record ID: 2018049218
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute.

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