The investigation of microorganisms from so far unexplored ecological niches has become an exciting subject in recent years. Lichens are ecologically highly adapted and also unique because the physiological integration of organisms provides conditions for persistence under extreme environmental conditions. Lichens are generally considered as symbiosis between fungi and green algae or cyanobacteria. These partnerships give raise to light-exposed and long-living joint structures, and the unique organization of lichens provides still unexplored environments for microbial communities. Recent studies showed that lichens harbour high abundances and diversity of bacteria but their exact location, ecology and biotechnological potential are still unexplored. The present paper summarizes briefly and gives an overview about the most important topics related to the study of the microbial community inhabiting the lichen thalli.Â
