Project Details
Projekt
Microheat-2: Carbon and energy turnover for complex substrates and intact soils
Subject Area
Soil Sciences
Microbial Ecology and Applied Microbiology
Microbial Ecology and Applied Microbiology
Term
since 2021
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 465122443
The efficiency of carbon turnover in soil depends on the initial substrate and on soil conditions, which together control the metabolic pathways and result in characteristic carbon and energy use efficiency. In the first project phase, the focus was on the utilization of simple substrates (glucose, cellobiose, cellulose) in homogenized soil, to facilitate a comprehensive characterization of substrate decomposition with activity measurements of specific enzymes and with calorespirometric measurements. This revealed interesting temporal patterns, such as the decoupling of the heat and CO2 flow peaks, and spatial effects, such as the change in decomposition kinetics with different degrees of substrate incorporation. We want to extend these findings in two main directions in the second phase. First, we are aiming for a broader selection of substrates with the same C content (6 C atoms; glucose, cellobiose, lysine, phenol) but varying combustion enthalpies and Gibbs energies to explore the influence of these substrate characteristics on the C and energy turnover, as well as enzyme activities and microbial communities in comparative incubations. This task is bundled in the core experiment "E-ComPLEX", in which several projects will participate and which will be carried out under the leadership of this project. The main objective of E-ComPLEX is to understand how efficiently the microbiome uses the primary substrate by fixing carbon and energy in its own biomass and by recycling building blocks from this secondary substrate. In addition to E-ComPLEX, we are conducting experiments with mixed substrates to investigate the influence of the stoichiometry of available nutrients in the soil, specifically the availability of nitrogen, on C and energy turnover during the utilization of C6 substrates. The other focus of the project in the second phase is on experiments with intact soil cores instead of homogenized soil. It is known that the position of the substrate in the pore space controls the accessibility for the microbiome as well as the supply of oxygen and nutrients and thus the turnover kinetics of the substrate. The project aims to investigate the influence of natural substrate distribution on C and energy turnover during the rewetting of dry soils. Although the initial substrates are unknown in intact soil, comparisons with repacked reference samples of the same storage, moisture, and labile C quantity are possible. With X-ray CT, the spatial heterogeneity can be detected and associated with differences in the turnover kinetics. The Microheat-2 project also provides important contributions to Priority Program 2322 in various ways: it carries out calorimeter measurements for other projects, contributes X-ray CT measurements and provides measurement data for modeling projects.
DFG Programme
Priority Programmes
