Study of metabolites from lichen-associated bacterial communities

Lichens are complex organisms resulting from the symbiosis between fungus, microalga and/or cyanobacteria and are source of metabolites of interest. As other living organisms harboring bacterial communities they could be considered as a mini-ecosystem. These bacterial communities most often belong to different phyla: Actinobacteria, Proteobacteria, with a dominance of Alphaproteobacteria and Firmicutes. In this study, we focused on the bacterial communities present on six lichens from Brittany coast (France) (Roccella fuciformis, R. phycopsis, Lichina confinis, L. pygmaea, Xanthoria aureola and X. calcicola). Abundance and diversity of these communities are dependent on several extrinsic factors (environmental) and/or intrinsic parameters including the chemical composition of their substrates (lichens). So, our aims are to elucidate the chemical composition of the studied lichens (extraction, isolation and structural identification) as well as those of associated bacterial communities. Some bacterial species were isolated from these lichens, identified by molecular fingerprints and their culture were optimized (media composition, pH and temperature). Due to the existence of chemical interactions between symbionts we target molecules with antibiotic properties.