Large reservoirs of natural gas in the oceanic subsurface sustain complex communities of anaerobic microbes, including archaeal lineages with potential to mediate oxidation of hydrocarbons such as methane and butane. Here we describe a previously unknown archaeal phylum, Helarchaeota, belonging to the Asgard superphylum and with the potential for hydrocarbon oxidation. We reconstruct Helarchaeota genomes from metagenomic data derived from hydrothermal deep-sea sediments in the hydrocarbon-rich Guaymas Basin. The genomes encode methyl-CoM reductase-like enzymes that are similar to those found in butane-oxidizing archaea, as well as several enzymes potentially involved in alkyl-CoA oxidation and the Wood-Ljungdahl pathway. We suggest that members of the Helarchaeota have the potential to activate and subsequently anaerobically oxidize hydrothermally generated short-chain hydrocarbons.
Bibliographical noteFunding Information:
This study was supported in part by an Alfred P. Sloan Foundation fellowship (FG-2016-6301) and National Science Foundation Directorate of Biological Sciences (Systematics and Biodiversity Sciences) (Award 1737298) to B.J.B. Sampling in Guaymas Basin and post-cruise work was supported by NSF Awards OCE-0647633 and OCE-1357238 to APT, respectively. The work conducted by the U.S. Department of Energy Joint Genome Institute, a DOE Office of Science User Facility, is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 provided to N.D. A.S. was supported by a Marie Curie IEF European grant (625521), a VR starting grant (2016-03559) and a WISE fellowship by the NWO-I Foundation of the Netherlands Organisation for Scientific Research. L.E. was funded by the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 704263. This work was supported by grants of the European Research Council (ERC Starting grant 310039-PUZZLE_CELL), the Swedish Foundation for Strategic Research (SSF-FFL5) and the Swedish Research Council (VR grant 2015-04959) to T.J.G.E.