EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Physiological responses of soil microorganisms to weeks, years, and decades of soil warming

Andrea Söllinger1, Joana Séneca2, Mathilde Borg Dahl3, Liabo L. Motleleng1, Judith Prommer2, Erik Verbruggen4, Bjarni D. Sigurdsson5, Ivan Janssens4, Josep Peñuelas6,7, Tim Urich3, Andreas Richter2, and Alexander T. Tveit1
Andrea Söllinger et al.
  • 1Department of Arctic and Marine Biology, UiT The Arctic University of Norway, Tromsø, Norway
  • 2Centre for Microbiology and Environmental Systems Science, University of Vienna, Vienna, Austria
  • 3Institute of Microbiology, University of Greifswald, Greifswald, Germany
  • 4PLECO, University of Antwerp, Antwerp, Belgium
  • 5Agricultural University of Iceland, Borgarnes, Iceland
  • 6CSIC, Global Ecology Unit CREAF-CSIC-UAB, Barcelona, Spain
  • 7CREAF, Barcelona, Spain

How soil microorganisms respond to global warming is a key question in microbial ecology and eminently relevant for soil ecosystems, the terrestrial carbon cycle, and the climate system. However, physiological responses of soil microorganisms – key to infer future soil-climate feedbacks – are poorly understood.

We here make use of the longest lasting in situ soil warming experiment worldwide, ForHot, in which an Icelandic subarctic grassland site has been exposed to natural geothermal soil warming for more than 50 years. Using a metatranscriptomics approach, allowing the comprehensive study of the entire active soil microbial community and their functions by analysing expressed genes, we revealed key physiological responses of soil Bacteria to medium- (8 years) and long-term (>50 years) soil warming of +6 °C.

Irrespective of the duration of warming, we observed a community-wide upregulation of central (carbohydrate) metabolisms and cell replication and a downregulation of the bacterial protein biosynthesis machinery in the warmed soils. This coincided with a decrease of microbial biomass, a decrease of total and biomass-specific RNA content, and lower soil substrate concentrations in the warmed soils. We conclude that higher biochemical reaction rates, caused by higher temperatures, allow soil Bacteria to reduce their cellular number of ribosomes, the macromolecular complexes carrying out protein biosynthesis. To further test this we revisited the site and conducted a short-term warming experiment (6 weeks, +6 °C), which supported our conclusion.

The downregulation of the protein biosynthesis machinery (i.e., the reduction of ribosomes) liberates energy and matter, leading to a resource re-allocation, and allows soil Bacteria to maintain high metabolic activities and cell division rates even after decades of warming.

How to cite: Söllinger, A., Séneca, J., Dahl, M. B., Motleleng, L. L., Prommer, J., Verbruggen, E., Sigurdsson, B. D., Janssens, I., Peñuelas, J., Urich, T., Richter, A., and Tveit, A. T.: Physiological responses of soil microorganisms to weeks, years, and decades of soil warming, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2657,, 2022.