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Methyl sulfides as intermediates in the anaerobic oxidation of methane

Moran, James J. and Beal, Emily J. and Vrentas, Jennifer M. and Orphan, Victoria J. and Freeman, Katherine H. and House, Christopher H. (2008) Methyl sulfides as intermediates in the anaerobic oxidation of methane. Environmental Microbiology, 10 (1). pp. 162-173. ISSN 1462-2912. https://resolver.caltech.edu/CaltechAUTHORS:20130327-081544064

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Abstract

While it is clear that microbial consortia containing Archaea and sulfate-reducing bacteria (SRB) can mediate the anaerobic oxidation of methane (AOM), the interplay between these microorganisms remains unknown. The leading explanation of the AOM metabolism is ‘reverse methanogenesis’ by which a methanogenesis substrate is produced and transferred between species. Conceptually, the reversal of methanogenesis requires low H_2 concentrations for energetic favourability. We used ^(13)C-labelled CH_4 as a tracer to test the effects of elevated H_2 pressures on incubations of active AOM sediments from both the Eel River basin and Hydrate Ridge. In the presence of H_2, we observed a minimal reduction in the rate of CH_4 oxidation, and conclude H_2 does not play an interspecies role in AOM. Based on these results, as well as previous work, we propose a new model for substrate transfer in AOM. In this model, methyl sulfides produced by the Archaea from both CH_4 oxidation and CO_2 reduction are transferred to the SRB. Metabolically, CH_4 oxidation provides electrons for the energy-yielding reduction of CO_2 to a methyl group (‘methylogenesis’). Methylogenesis is a dominantly reductive pathway utilizing most methanogenesis enzymes in their forward direction. Incubations of seep sediments demonstrate, as would be expected from this model, that methanethiol inhibits AOM and that CO can be substituted for CH_4 as the electron donor for methylogenesis.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1111/j.1462-2920.2007.01441.xDOIArticle
http://onlinelibrary.wiley.com/doi/10.1111/j.1462-2920.2007.01441.x/abstractPublisherArticle
ORCID:
AuthorORCID
Orphan, Victoria J.0000-0002-5374-6178
Freeman, Katherine H.0000-0002-3350-7671
House, Christopher H.0000-0002-4926-4985
Additional Information:© 2007 The Authors. Journal compilation © 2007 Society for Applied Microbiology and Blackwell Publishing Ltd. Received 15 April, 2007; accepted 11 August, 2007. Article first published online: 30 Sep. 2007. We thank Dr Michael Arthur for the use of his mass spectrometer, Denny Walizer for valuable technical assistance, Dr Shana Goffredi for assistance with the T-RFLP analysis and Dr Lisa Levin for providing samples from Hydrate Ridge. Graduate support for this project was provided by the Penn State Biogeochemical Research Initiative for Education (BRIE) funded by NSF (IGERT) Grant DGE-9972759. This work was also funded by the Penn State Astrobiology Research Center (through the National Astrobiology Institute), NOAA-NURP (UAF 05-0132) and the National Science Foundation (MCB-0348492).
Funders:
Funding AgencyGrant Number
Penn State Biogeochemical Research Initiative for Education (BRIE)UNSPECIFIED
NSFDGE-9972759
Penn State Astrobiology Research Center (PSARC)UNSPECIFIED
National Oceanic and Atmospheric Administration (NOAA)UAF 05-0132
NSFMCB-0348492
Issue or Number:1
Record Number:CaltechAUTHORS:20130327-081544064
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20130327-081544064
Official Citation:Moran, J. J., Beal, E. J., Vrentas, J. M., Orphan, V. J., Freeman, K. H. and House, C. H. (2008), Methyl sulfides as intermediates in the anaerobic oxidation of methane. Environmental Microbiology, 10: 162–173. doi: 10.1111/j.1462-2920.2007.01441.x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:37640
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:09 May 2013 19:43
Last Modified:09 Mar 2020 13:18

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