More microbial taxa start growing with soil warming Raw sequence reads

Soil microorganisms control the fate of soil organiccarbon. Warming accelerates their activities putting large carbonstocks at risk of decomposition. Existing knowledge about microbialresponses to warming is based on community-level measurements, leavingthe underlying mechanisms unexplored and hindering predictions. In along-term soil warming experiment in a Subarctic grassland, weinvestigated how active populations of microorganisms responded toelevated soil temperatures (+6C) and the influence of plant roots,by measuring taxon-specific growth rates using stable isotope probingand 18O water vapor equilibration. Contrary to prior assumptions,increased community growth was due to a greater number of active taxa,not to higher growth rates. We also found that root presence enhancedmicrobial growth at ambient temperatures but not at elevatedtemperatures, indicating a shift in plant-microbe interactions. Ourresults, thus, reveal a novel mechanism of how microorganisms respondto warming, that cannot be inferred from community-level measurements. Sequencing was performed at the Joint Microbiome Facility of the Medical University of Vienna and the University of Vienna under the project ID JMF-2107-05.