A lichen is a symbiotic organism composed of a fungal partner, the mycobiont, and a photosynthetic partner, the photobiont, which can be an alga and/or a cyanobacterium (Armaleo & Clerc, 1991;Schwendener, 1868). Occurrences of various bacteria, fungi and algae on and within lichen thalli have been described in recent years, demonstrating that lichens essentially are complex meta-