P17 - Microbial networks

Self-organized microbial networks in soil aggregates and their dynamics in the root soil continuum

Association network of soil bacterial community members (OTUs depicted as circles) and soil organic carbon fractions (hexagons). Green lines are positive, red lines negative associations. OTU nodes are sized by their relative abundances and colored according to their phylum-level classification

Plants roots provide soils with large amounts of energy rich carbon (C) sources which trigger a cascade of abiotic and biotic reactions with consequences for soil structure. Soil microorganisms are the most important biological players in this process. The objective of this project is to characterize the microbial community dynamics as induced by root released plant products from roots across the rhizosphere into the bulk soil, i.e., the root soil continuum, and identify interaction rules which shape microbial diversity and community function at the soil aggregate level. We suspect that in an agricultural setting the root soil continuum is characterized by two contrasting gradients: a decline of energy rich C-sources, and a relative increase of N with increasing distance from the root surface. The different CN ratios impose selective pressure on the self-organization of microbial communities in aggregates, which emerge as structurally and functionally distinct entities. We hypothesize that with increasing distance from the roots, the diversity of microbial communities as well as the carbon use efficiency in soil aggregates will increase. The rules of interactions change: While the presence of easily available C- sources under the limitation of N will favor competition between community members in the rhizosphere, further away from the roots, the more complex carbons sources will foster cooperation. These contrasting organization patterns should become evident by network analysis.

Link to English scientific abstract

Link to German scientific abstract