Novel approach using substrate-mediated radiolabelling of RNA to link metabolic function with the structure of microbial communities.

A novel concept was developed applying radioisotope-labelled substrate incorporation into the biomass. The resulting radiolabelled RNA was used both as an indicator of activity and as a template for gaining structural and functional information about a substrate-utilizing microbial community. Sequences of PCR products are separated via cloning or using molecular fingerprinting techniques. Nucleic acids from predominant clones or the whole molecular fingerprinting pattern are transferred to a membrane and hybridized with the radiolabelled sample RNA. Scanning of the hybridized blots for radioactivity indicates the members involved in the utilization of the substrate. This novel 'random walk' approach using radioisotope probing was evaluated in a model community experiment.