Ascomycete fungi on dimension stone of the Burg Gleichen, Thuringia

In the present study, the diversity of ascomycete fungi was investigated on two wall areas of the Burg Gleichen, Thuringia (Germany), made of various types of sandstones, travertine and Grenzdolomit. From a W-exposed, shaded wall area, free-living ascomycetes (mainly black fungi) and green algae could be retrieved from sandstone lithologies. Sandstone from an ESE-exposed area was mainly colonized by lichen ascomycetes and the lichen alga Trebouxia. Both areas share a small number of generalist species, related to the ascomycete black fungi Sarcinomyces petricola, Phaeococcomyces chersonesos and Stichococcus mirabilis. Free-living black fungi were isolated and characterized with respect to cell wall morphology and melanin content. A remarkably rigid melanin layer, incorporated in the cell wall of a Cladosporium isolate is presented in detail.