Biodiversity of photosynthetic micro-organisms dwelling on stone monuments

A critical survey of literature data for the biodeteriogens acting on stone monuments was combined with the results of our investigations performed by traditional and biomolecular (ARDRA) methods. It was showed that the photosynthetic micro-organisms dwelling on stone monuments have a rather ample biodiversity, and this was also confirmed by our data on axenic cyanobacterial strains isolated from Italian monuments. The correlation between the literature data reporting the presence of photosynthetic micro-organisms, and the nature of the stone substrate showed that the cyanobacteria Chroococcus, Myxosarcina, Pleurocapsa and Scytonema, and the chlorophyta Apatococcus and Stichococcus were associated with calcareous substrates, while Nostoc spp. were more frequently associated with artificial substrates. We also demonstrated that Lyngbya B2 and Apatococcus B4, isolated from monuments inoculated on stone slabs differing in porosity and surface roughness, had a preference for calcareous lithotypes with high values of roughness and porosity.