Functional partitioning of prokaryotic diversity under different land-use regimes

ProFunD focuses on the study of bacterial species involved in the degradation of root exudates and plant litter in different soil compartments. The aim is to understand the relationship between functional bacterial biodiversity, plant diversity and productivity, soil parameters and land use.

Bacteria account for up to 60-80% of all soil organisms and therefore represent important control points of the biogeochemical nutrient cycle, soil fertility and pest control. The specific composition of the bacterial community therefore controls key ecosystem processes. It has been shown that acidobacteria, actinobacteria and alphaproteobacteria are not randomly distributed in the soil but preferentially colonise different soil compartments. Differences in bacterial community composition drive organic carbon sequestration, nutrient regeneration and the bacterial food chain. Nevertheless, the distribution of different species of these bacterial groups, their influence by biotic and abiotic parameters, and the functional consequences of these parameters on nutrient cycling is still under-researched.

In this project we will examine the partitioning of active members of Acidobacteria, Actinobacteria and Alphaproteobacteria between the rhizosphere of different dominant plant species and the surrounding soil particles, as well as the function of these dominant groups on carbon cycling under different ecological conditions.

• We will look at the spatial distribution of Acidobacteria, Actinobacteria and Alphaproteobacteria between rhizosphere and soil particles at the taxonomic level of species using Illumina high-throughput sequencing of 16S rRNA and correlate species abundances with the specific composition of plant exudates, other plant properties, soil physicochemical parameters and land-use gradients.

• We will analyse the contribution of different bacteria to carbon and nitrogen transfer from plant roots (respectively plant litter) to soil in functional mesocosms. To do this, we will use a combination of different isotope labels in techniques such as 13C/ 15N-RNA Stable Isotope Probing (SIP) and 13C-RNA Captured RNA Isotope Probing (CARIP).
• In addition, we will determine the relative abundance of Acidobacteria, Actinobacteria and Alphaproteobacteria at different taxonomic resolution levels (species, genus, family, order, class, phylum) using Illumina high-throughput sequencing of 16S rRNA. This will provide a deeper understanding of the relationship between bacterial diversity, functional bacterial biodiversity, plant diversity and productivity, soil parameters and land use.