Using metagenomic tools for biocontrol: analysis of moss- and lichen-associated microbial communities.

Bryophytes and lichens represent interesting bio-resources; their intense interaction with microorganisms is only partly understood. Recently, it was shown that both groups of cryptogams are colonized at high abundances by specific microbial communities. They are involved in important functions for the moss plantlets as well as for the lichen symbiosis. To characterize biodiversity of associated microbial communities, we applied a combination of methods: phylogenetic diversity, spatial organization and specificity were assessed using clone libraries, fluorescent in-situ hybridization (FISH) and SSCP fingerprinting. These data were placed into an ecological context by multivariate analysis using CANOCO software. Furthermore, metagenomic and metaproteomic data sets were explored. In addition, isolates were investigated regarding their interaction with plants. According to our results, cryptogam-associated microbial communities comprise a unique pool of highly diverse, mostly uncultivable and host-specific microorganisms. Structure of the communities is strongly dependent on a-biotic and biotic factors. Associated bacteria have a function for nutrient supply and pathogen defence. Knowledge about diversity and function was used to isolate bacteria for biotechnological applications. A high proportion of isolates showed antifungal activities and a remarkable plant growth promotion by nitrogen fixation, phosphate solubilisation and production of phytohormons as well as an extraordinarily high biocontrol potential.