Implications of energy and matter fluxes on microbial diversity and complexity in soil systems

• Applicant: Professor Christoph Tebbe, Ph.D.
• Subject Area: Soil Sciences ; Microbial Ecology and Applied Microbiology
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 500452744

Microbial communities can be considered as the central engine promoting the turnover of soil organic matter (SOM), thereby sustaining biogeochemical cycles and other important ecosystem services. However, the importance of biodiversity for providing these services is still poorly understood. The objective of this research project is to characterize the implications of energy and matter fluxes on microbial diversity and community complexity in order to gain a systems understanding of how energy and matter are processed in soil. The experimental studies of this project are especially linked to the three newly interdisciplinary central platform experiments of the DFG SPP2322 established to elucidate the implications of different soils, substrates and boundary conditions (water potential, temperature) on energy and matter fluxes. We will characterize the abundance and diversity of microbial populations (Bacteria, Archaea, Fungi) from DNA of soil samples and individual soil aggregates by PCR and determine their diversity and composition by sequencing 16S rRNA gene and ITS amplicons. Based on these data, we will characterize substrate-induced temporal and spatial changes of the microbiome. Furthermore, we will link information on the microbiome to matter and energy fluxes, microbial metabolism, biomass and necromass pools. Our data will support model data integration by adding information about the abundance, diversity and dynamics of soil microbial communities. We will test five hypotheses to establish the link between microbial diversity and the Gibbs energy and molecular structure of the substrates within different soils and under variation of water potential and temperature. We suspect that bacterial and fungal communities show distinct responses to energy and matter inputs, thus representing different thermodynamic energy flux channels. This equally applies to oligotrophic and copiotrophic bacteria. Utilizing our new protocol of analysing the microbial metagenome of individual soil aggregates, we will try to unveil patterns of potential community interactions by means of network analyses. Furthermore, following a mm-depth gradient from litter into deeper soil layers, we will test if the diffusion of dissolved organic carbon through the detritussphere creates a gradient with an increasing contribution of microbiomes to the decomposing necromass. Finally, we will utilize a clay gradient in experimental soils to reduce the bioavailability of chitin as a necromass-typical substrate, thereby modifying to energy use and shifting from inter-aggregate to intra-aggregate microbial metabolism. – Overall the results of this project should enhance our understanding how energy and substrates shape the soil microbiome and their efficiency in contributing to the turnover of SOM.

• DFG Programme: Priority Programmes
• Subproject of: SPP 2322: Systems ecology of soils – Energy Discharge Modulated by Microbiome and Boundary Conditions (SoilSystems)
• Co-Investigator: Damien Finn, Ph.D.