Metagenomic identification of active methanogens and methanotrophs in serpentinite springs of the Voltri Massif, Italy

William J Brazelton; Christopher N Thornton; Alex Hyer; Katrina I Twing; August A Longino; Susan Q Lang; Marvin D Lilley; Gretchen L Früh-Green; Matthew O Schrenk

doi:10.7717/peerj.2945

Metagenomic identification of active methanogens and methanotrophs in serpentinite springs of the Voltri Massif, Italy

PeerJ. 2017 Jan 26:5:e2945. doi: 10.7717/peerj.2945. eCollection 2017.

Authors

William J Brazelton¹, Christopher N Thornton¹, Alex Hyer¹, Katrina I Twing², August A Longino¹, Susan Q Lang³, Marvin D Lilley⁴, Gretchen L Früh-Green⁵, Matthew O Schrenk²

Affiliations

¹ Department of Biology, University of Utah , Salt Lake City , UT , United States.
² Department of Earth and Environmental Sciences, Michigan State University , East Lansing , MI , United States.
³ Department of Earth and Ocean Sciences, University of South Carolina, Columbia, SC, United States; Department of Earth Sciences, ETH Zurich, Zurich, Switzerland.
⁴ School of Oceanography, University of Washington , Seattle , WA , United States.
⁵ Department of Earth Sciences, ETH Zurich , Zurich , Switzerland.

Abstract

The production of hydrogen and methane by geochemical reactions associated with the serpentinization of ultramafic rocks can potentially support subsurface microbial ecosystems independent of the photosynthetic biosphere. Methanogenic and methanotrophic microorganisms are abundant in marine hydrothermal systems heavily influenced by serpentinization, but evidence for methane-cycling archaea and bacteria in continental serpentinite springs has been limited. This report provides metagenomic and experimental evidence for active methanogenesis and methanotrophy by microbial communities in serpentinite springs of the Voltri Massif, Italy. Methanogens belonging to family Methanobacteriaceae and methanotrophic bacteria belonging to family Methylococcaceae were heavily enriched in three ultrabasic springs (pH 12). Metagenomic data also suggest the potential for hydrogen oxidation, hydrogen production, carbon fixation, fermentation, and organic acid metabolism in the ultrabasic springs. The predicted metabolic capabilities are consistent with an active subsurface ecosystem supported by energy and carbon liberated by geochemical reactions within the serpentinite rocks of the Voltri Massif.

Keywords: Metagenomics; Methanogenesis; Methanotrophy; Serpentinization.

Grants and funding

WJB received funding from a NASA Astrobiology Institute Postdoctoral Fellowship and University of Utah start-up funds. Additional funding to the Schrenk lab was provided by the Alfred P. Sloan Foundation’s Deep Carbon Observatory and the NASA Astrobiology Institute (NASA-CAN5 through the Carnegie Institution for Science). SQL and GLFG were funded by SNF Project 200020 14389. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.