Autor:innen:
Laurent K. Kidinda | Chair of Soil Resources and Land Use, Institute of Soil Science and Site Ecology, TU Dresden, Dresden, Germany | Germany
Dr. Doreen Babin | Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany | Germany
Prof. Dr. Sebastian Doetterl | Soil Resources, ETH Zurich, Zurich, Switzerland | Switzerland
Prof. Dr. Karsten Kalbitz | Chair of Soil Resources and Land Use, Institute of Soil Science and Site Ecology, TU Dresden, Dresden, Germany
Benjamin Bukombe | Institute of Geography, Augsburg University, Augsburg, Germany
Dr. Kornelia Smalla | Julius Kühn Institute (JKI), Federal Research Centre for Cultivated Plants, Institute for Epidemiology and Pathogen Diagnostics, Braunschweig, Germany | Germany
Prof. Dr. Basile B. Mujinya | Biogeochemistry and Ecology of Tropical Soils and Ecosystems, University of Lubumbashi, Lubumbashi, DR Congo
Dr. Cordula Vogel | Chair of Soil Resources and Land Use, Institute of Soil Science and Site Ecology, TU Dresden, Dresden, Germany
Extracellular polymeric substances (EPS) that form microbial biofilms in soil can serve as a nutrient sink or source, depending on the geochemical environment and the physiological needs of the microbes. However, it is not clear how concentrations of the major components of EPS (i.e., proteins and polysaccharides) relate to microbial community composition and microbial investment in nutrient acquisition in deeply weathered (old) soils, whose physicochemical properties differ greatly from better-studied less weathered (younger) soils. Here, we evaluate these relationships using top- (0-10 cm) and subsoils (30-70 cm) from tropical montane forests and croplands that represent a gradient in rock-derived nutrient content and organic carbon stabilization potential. We measured EPS, microbial community composition (bacterial 16S rRNA gene and fungal ITS), extracellular enzyme activity, and microbial biomass at the end of a 70- to 120-day incubation experiment. In addition, we evaluated microbial investment in nutrient acquisition using vector analysis based on ecoenzymatic stoichiometry. We show that high microbial investment in nutrient acquisition is associated with high EPS production efficiency (EPS per unit microbial biomass), while high nutrient availability is associated with low EPS production efficiency. Ongoing analysis of high-throughput amplicon sequencing will allow us to determine whether EPS concentrations are associated with specific fungal or bacterial taxa across soil depths, land use types and soil types.