Microbial growth under drought is confined to distinct taxa and modified by potential future climate conditions

• Published in: Nature communications 2023-09, Vol.14 (1), p.5895-5895, Article 5895
• Main Authors: Metze, Dennis, Schnecker, Jörg, Canarini, Alberto, Fuchslueger, Lucia, Koch, Benjamin J., Stone, Bram W., Hungate, Bruce A., Hausmann, Bela, Schmidt, Hannes, Schaumberger, Andreas, Bahn, Michael, Kaiser, Christina, Richter, Andreas
• Format: Article
• Language: English
• Subjects: 49/22; 49/23; 631/158/2165; 631/158/2466; 631/158/855; 631/326/171/1818; Carbon cycle; Carbon dioxide; Carbon sequestration; Climate change; Climate-change ecology; Climatic conditions; Drought; Drought resistance; ENVIRONMENTAL SCIENCES; Exposure; Grasslands; Growth rate; High temperature; Humanities and Social Sciences; Microbial ecology; Microorganisms; multidisciplinary; Nutrient cycles; Science; Science (multidisciplinary); Soil microbiology; Soil microorganisms; Soils; Stable isotope analysis; Stable isotopes; Taxa; Water vapor
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-023-41524-y

Climate change increases the frequency and intensity of drought events, affecting soil functions including carbon sequestration and nutrient cycling, which are driven by growing microorganisms. Yet we know little about microbial responses to drought due to methodological limitations. Here, we estimate microbial growth rates in montane grassland soils exposed to ambient conditions, drought, and potential future climate conditions (i.e., soils exposed to 6 years of elevated temperatures and elevated CO 2 levels). For this purpose, we combined 18 O-water vapor equilibration with quantitative stable isotope probing (termed ‘vapor-qSIP’) to measure taxon-specific microbial growth in dry soils. In our experiments, drought caused >90% of bacterial and archaeal taxa to stop dividing and reduced the growth rates of persisting ones. Under drought, growing taxa accounted for only 4% of the total community as compared to 35% in the controls. Drought-tolerant communities were dominated by specialized members of the Actinobacteriota, particularly the genus Streptomyces . Six years of pre-exposure to future climate conditions (3 °C warming and + 300 ppm atmospheric CO 2 ) alleviated drought effects on microbial growth, through more drought-tolerant taxa across major phyla, accounting for 9% of the total community. Our results provide insights into the response of active microbes to drought today and in a future climate, and highlight the importance of studying drought in combination with future climate conditions to capture interactive effects and improve predictions of future soil-climate feedbacks. Climate change increases the frequency and intensity of drought events, affecting soil functions driven by microorganisms. Here, Metze et al. develop a method to estimate microbial growth rates in dry soils, and provide insights into the response of active microbes to drought today and in potential future climate conditions (high temperatures and CO2 levels).