EcoEnergeticS 2

Zellökonomische und bioenergetische Implikationen mikrobieller Kooperation in Böden

01.01.2025 bis 31.12.2028

Soil microorganisms are the principal actors in soil organic matter turnover, and determine the fate of carbon in soils. Their energetic and material efficiency therefore greatly influence soil health and the global climate. However, microbial diversity, and the myriad possible interactions between these organisms, challenge our ability to relate community structure to carbon and energy-use efficiency (CUE and EUE). This project investigates the cooperative interactions that are increasingly recognized as crucially important in microbial communities. We target two specific cases in soil: “Metabolic cross-feeding” refers to one microorganism consuming a metabolic intermediate produced by another. “Enzyme sharing” occurs when extracellular enzymatic depolymerization releases resources that are then also available to other community members, which do not synthesize that enzyme themselves.
Our overarching hypotheses are that (a) cross-feeding increases CUE and EUE by reducing the need for a broad portfolio of intracellular enzymes to carry out all metabolic pathways within each cell. Instead, individual taxa can specialize in particular metabolic pathways and thereby achieve higher efficiencies; and (b) enzyme sharing increases CUE and EUE by reducing the need for multiple extracellular isoenzymes that degrade the same complex, polymeric resources. Instead, each polymer is degraded by a small range of highly efficient enzymes. The project will proceed through five work packages (WPs).
WP1 will distinguish these two mechanisms and their responses to agricultural practices, while generating deep metagenomic data to support subsequent WPs. WP2 will couple characterization of cooperation with detailed analysis of CUE, EUE and substrate-use efficiency (SUE) and determine their relationship to substrate complexity. WP3 will harness methods of metabolic flux analysis (MFA), developed in Phase 1 of this SPP, alongside DNA and RNA stable isotope probing, to verify the mechanisms underlying phenomena revealed in the first two WPs. WP4 will take a community coalescence approach to the central experiment on functional complexity, in which communities of different complexities will be assembled. Time-series measurements will examine the development of cooperation and the relative importance of trait diversity versus community cooperation as determinants of CUE and EUE. Finally, WP5 will contribute to the central experiment by performing MFA to determine the biochemical CUE and characterizing the degree of cooperation as a key factor shaping the response of microbial efficiencies to disturbance.
This project will provide unprecedented insight into the relationship between microbial interactions and carbon cycling in soil. This will contribute a focused yet integrative ecological perspective to the SPP, while generating results of wide significance to the understanding and steering of microbiome function in and beyond soil ecosystems.