EGU22-2909, updated on 27 Mar 2022
https://doi.org/10.5194/egusphere-egu22-2909
EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Microbial survival through high metabolic rates in a deep and hot subseafloor environment

Florian Schubert2, Felix Beulig1, Rishi Ram Adhikari3, Clemens Glombitza4, Verena Heuer3, Kai-Uwe Hinrichs3, Kira Homola5, Fumio Inagaki6,7, Bo Barker Jørgensen1, Jens Kallmeyer2, Sebastian Krause8, Yuki Morono6, Justine Sauvage5,9, Arthur Spivack5, and Tina Treude8,10
Florian Schubert et al.
  • 1Center for Geomicrobiology, Department of Bioscience, Aarhus University, Ny Munkegade 114, 8000 Aarhus C, Denmark
  • 2GFZ German Research Center for Geosciences, Section 3.7 Geomicrobiology, Telegrafenberg, 14473 Potsdam, Germany (florian.schubert@gfz-potsdam.de)
  • 3MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Strasse 8, 28359 Bremen, Germany
  • 4Department of Environmental Systems Science, ETH Zürich, Universitätstrasse 16, 8092 Zürich, Switzerland
  • 5Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, 215 South Ferry Road, RI 02882, USA
  • 6Kochi Institute for Core Sample Research, Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Nankoku, Kochi 783-8502, Japan
  • 7Mantle Drilling Promotion Office, Institute for Marine-Earth Exploration and Engineering, JAMSTEC, Yokosuka 237-0061, Japan
  • 8Department of Earth, Planetary and Space Sciences, University of California Los Angeles, Los Angeles, CA 90095, USA
  • 9Department of Marine Sciences, University of Gothenburg, Carl Skottsbergs gata 22B, 413 19 Göteborg, Sweden
  • 10Department of Atmospheric and Oceanic Sciences, University of California Los Angeles, Los Angeles, CA 90095, USA

A fourth of the global seabed sediment volume is buried at depths where temperatures exceed 80 °C, a previously proposed thermal barrier for life in the subsurface. Here, we demonstrate, utilizing an extensive suite of radiotracer experiments, the prevalence of active methanogenic and sulfate-reducing populations in deeply buried marine sediment from the Nankai Trough subduction zone, heated to extreme temperature (up to ~120 °C). Sediment cores were recovered during International Ocean Discovery Program (IODP) Expedition 370 to Nankai Trough, off the cost of Moroto, Japan. The steep geothermal gradient of ~100 °C km-1 allowed for the exploration of most of the known temperature range for life over just 1 km of drill core. Despite the high temperatures, microbial cells were detected almost throughout the entire sediment column, albeit at extremely low concentration of <500 cells per cm³ in sediment above ~50 °C. In millions of years old sediment a small microbial community subsisted with high potential cell-specific rates of energy metabolism, which approach the rates of active surface sediments and laboratory cultures. Even under the most conservative assumptions, potential biomass turnover times for the recovered sediment ranges from days to years and therefore many orders of magnitude faster than in colder deep sediment.

Our discovery is in stark contrast to the extremely low metabolic rates otherwise observed in the deep subseafloor. As cells appear to invest most of their energy to repair thermal cell damage in the hot sediment, they are forced to balance delicately between subsistence near the upper temperature limit for life and a rich supply of substrates and energy from thermally driven reactions of the sediment organic matter.

How to cite: Schubert, F., Beulig, F., Adhikari, R. R., Glombitza, C., Heuer, V., Hinrichs, K.-U., Homola, K., Inagaki, F., Jørgensen, B. B., Kallmeyer, J., Krause, S., Morono, Y., Sauvage, J., Spivack, A., and Treude, T.: Microbial survival through high metabolic rates in a deep and hot subseafloor environment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2909, https://doi.org/10.5194/egusphere-egu22-2909, 2022.

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