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

Emerging properties of microbial communities are a result of the functional potentials of their constituting members. The specific conditions in the rhizosphere select for microorganisms that, on one side, support plant growth in return for receiving energy rich carbon sources from rhizodepositions, and, on the other side, compete with plant roots for growth nutrients, especially soil nitrogen (N) and phosphorous (P). These can be considered as positive and negative feedbacks between the plant and the rhizosphere microbial community, respectively. During the 1st phase of this SPP 2089, we established a protocol for extracting from individual aggregates and characterized the bacterial community composition by DNA 16S rRNA PCR amplicon sequencing. Networks between bacterial community members obtained with aggregate DNA indicated a strong effect of root hairs not seen with alpha-diversity measurements. For the 2nd phase we take this approach further and characterize the aggregates at the level of their microbial functional potentials, based on studying the diversity of alternative genetic versions of microbial key functions contributing to soil N transformation and P mobilisation. We will combine our molecular microbial community results with information on the aggregates’ 3D architecture and other physico-chemical aggregate properties, as provided from SPP partners. In addition, functional adaptations will be studied by shotgun metagenomics of individual soil aggregates.

Link to English scientific abstract

Link to German scientific abstract