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Monodeuterated Methane, an Isotopic Tool To Assess Biological Methane Metabolism Rates

Marlow, Jeffrey J. and Steele, Joshua A. and Ziebis, Wiebke and Scheller, Silvan and Case, David and Reynard, Linda M. and Orphan, Victoria J. (2017) Monodeuterated Methane, an Isotopic Tool To Assess Biological Methane Metabolism Rates. mSphere, 2 (4). Art. No. e00309. ISSN 2379-5042. PMCID PMC5566838. https://resolver.caltech.edu/CaltechAUTHORS:20170914-133025440

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Abstract

Biological methane oxidation is a globally relevant process that mediates the flux of an important greenhouse gas through both aerobic and anaerobic metabolic pathways. However, measuring these metabolic rates presents many obstacles, from logistical barriers to regulatory hurdles and poor precision. Here we present a new approach for investigating microbial methane metabolism based on hydrogen atom dynamics, which is complementary to carbon-focused assessments of methanotrophy. The method uses monodeuterated methane (CH_3D) as a metabolic substrate, quantifying the aqueous D/H ratio over time using off-axis integrated cavity output spectroscopy. This approach represents a nontoxic, comparatively rapid, and straightforward approach that supplements existing radiotopic and stable carbon isotopic methods; by probing hydrogen atoms, it offers an additional dimension for examining rates and pathways of methane metabolism. We provide direct comparisons between the CH_3D procedure and the well-established ^(14)CH_4 radiotracer method for several methanotrophic systems, including type I and II aerobic methanotroph cultures and methane-seep sediment slurries and carbonate rocks under anoxic and oxic incubation conditions. In all applications tested, methane consumption values calculated via the CH_3D method were directly and consistently proportional to ^(14)C radiolabel-derived methane oxidation rates. We also employed this method in a nontraditional experimental setup, using flexible, gas-impermeable bags to investigate the role of pressure on seep sediment methane oxidation rates. Results revealed an 80% increase over atmospheric pressure in methanotrophic rates the equivalent of ~900-m water depth, highlighting the importance of this parameter on methane metabolism and exhibiting the flexibility of the newly described method.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1128/mSphereDirect.00309-17DOIArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5566838/PubMed CentralArticle
ORCID:
AuthorORCID
Scheller, Silvan0000-0002-0667-9224
Orphan, Victoria J.0000-0002-5374-6178
Additional Information:© 2017 Marlow et al. This is an open-access article distributed under the terms of the Creative Commons Attribution 4.0 International license. Received 18 July 2017; Accepted 31 July 2017; Published 23 August 2017. We thank the captains, crew, Alvin group, Jason group, and Science party members from the RV Atlantis on legs AT-15-68 and AT-18-10. Water analyzer measurements were conducted in the laboratory of Alex Sessions at the California Institute of Technology with technical support from Lichun Zhang. We are indebted to William Berelson at the University of Southern California and Nick Rollins for use of their pressure chambers and assistance with the incubation experiments. We thank Alex Sessions, Woodward Fischer, Dianne Newman, Tori Hoehler, Amy Rosenzweig, and Daniel Stolper for helpful conversations during the preparation of the manuscript. This study was funded by grants from the U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research (DE-SC001057), and the NASA Astrobiology Institute (award number NNA13AA92A) and by support from the Gordon and Betty Moore Foundation through grant GBMF3780 (to V.J.O.). J.J.M. was supported by a National Energy Technology Laboratory Methane Hydrate Research Fellowship funded by the National Research Council of the National Academies. This research used resources of the Oak Ridge Leadership Computing Facility. Oak Ridge National Laboratory is supported by the Office of Science of the U.S. Department of Energy. We declare no conflict of interest.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC001057
NASANNA13AA92A
Gordon and Betty Moore FoundationGBMF3780
National Research CouncilUNSPECIFIED
Issue or Number:4
PubMed Central ID:PMC5566838
Record Number:CaltechAUTHORS:20170914-133025440
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20170914-133025440
Official Citation:Monodeuterated Methane, an Isotopic Tool To Assess Biological Methane Metabolism Rates Jeffrey J. Marlow, Joshua A. Steele, Wiebke Ziebis, Silvan Scheller, David Case, Linda M. Reynard, Victoria J. Orphan mSphere Aug 2017, 2 (4) e00309-17; DOI: 10.1128/mSphereDirect.00309-17
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:81447
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Sep 2017 21:47
Last Modified:03 Oct 2019 23:46

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