Prokaryotic Diversity Changes and their Functional Interrelation to Land Use (ProFIL)

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So far, studies of the functional relevance of bacterial diversity have mostly been limited to a few groups of Proteobacteria involved in the N-cycle and to rhizosphere bacteria. Results of the preceding funding period revealed that Acidobacteria represent up to 64% of all bacteria in soils of the three exploratories and that the specific physiological activity of Acidobacteria is unexpectedly high particularly in soils from the Schwäbische Alb. Using a land use gradient across the three exploratories as the major variable, we propose to conduct a detailed study of the composition, physiological key traits and the functional implications of Acidobacteria diversity. In order to identify the determinants of Acidobacteria diversity and activity, deep sequencing of ribosomal RNA genes and quantification of the ribosome content will be conducted for samples from all 300 experimental plots and their correlation with environmental parameters will be investigated by multivariate statistical analyses. The effects of spatial and short-term temporal variability of the Acidobacteria community structure will be studied for a selected plot. Novel information on the metabolic traits of dominant soil Acidobacteria will be obtained by analyses of existing metagenomic libraries and by characterizing representative isolates. The functional diversity and role of Acidobacteria in the soil carbon and nitrogen cycles will be resolved using a combination of stable isotope probing and capture probing of incorporated carbon substrates.