1. Particular species of Acidobacteria and Actinobacteria catalyse the degradation of refractory organic carbon and plant litter, and dominate in bulk soil particles.
2. Specifically adapted Alphaproteobacteria constitute a dominant fraction within the plant rhizosphere and control the flux of organic carbon from plants to the soil environment.
3. Different species of Acidobacteria, Actinobacteria, and Alphaproteobacteria are adapted to and occur under different environmental conditions in bulk soils.
ProFunD focuses on bacterial species involved in the degradation of root exudates and leaf litter that dominate different soil compartments, with the aim to better understand the links between functional bacterial biodiversity, plant diversity and productivity, edaphic factors and land use.
Bacteria can constitute up to 60-80% of all soil microbiota and are important determinants of the biogeochemical cycling of nutrients, of soil fertility and pathogen control. The specific composition of soil bacterial communities is likely to control major ecosystem processes. Evidence has shown that members of the Acidobacteria, Actinobacteria and Alphaproteobacteria are distributed in the soil environment in a non-random fashion and preferentially colonize different compartments. Differences in the overall composition of the bacterial community across different soil compartments are expected to have major effects on organic carbon sequestration, nutrient regeneration and turnover, and on the microbial food chain. Yet, very little is known on the partitioning of different species of these bacterial groups in the soil environment, their abiotic and biotic controls, and the functional implications of these diversity patterns for the carbon and nutrient cycling.
This work intends to determine the partitioning of active Acidobacteria, Actinobacteria, and Alphaproteobacteria between the rhizosphere of dominant plant species and the bulk soil particles and to quantify the functions of dominant members of these three groups in the soil carbon fluxes under different ecological conditions.
- The distribution of individual species of Acidobacteria, Actinobacteria, and Alphaproteobacteria between the rhizosphere of six dominant plant species and bulk soil particles will be systematically studied by high throughput Illumina sequencing of the 16S rRNA and will then be related to the specific composition of plant exudates, specific plant traits, physicochemical soil parameters and land use.
- The contribution of bacteria affecting the C- and N-transfer from plant roots to bulk soil, and from plant litter to bulk soil, will be evaluated in a series of Functional Diversity Mesocosm experiments. We will apply a combination of 13C/ 15N-RNA Stable Isotope Probing (SIP) and 13C-RNA Captured RNA Isotope Probing (CARIP) to probe the assimilatory capabilities of these bacteria and deduce their different functions in soil.
- The relative abundance of Acidobacteria, Actinobacteria and Alphaproteobacteria in all 300 experimental plots (EPs) will be quantified by high throughput Illumina sequencing of the 16S rRNA, as a prerequisite for a better understanding of the interrelation between these bacteria, plant diversity, edaphic factors and land use.
Work will be conducted in close cooperation with several other microbiological projects, as well as with plant and soil-based studies to enable data integration and synthesis.
Further project contribution of Prof. Dr. Jörg Overmann, Dr. Johannes Sikorski: MicroSYSteM II
Previous project contribution of Prof. Dr. Michael Friedrich, Prof. Dr. Jörg Overmann, Dr. Johannes Sikorski, Dr. Tim Richter-Heitmann: ProFIL