PHOTOTROPHIC BIODETERIOGENS ON LITHOID SURFACES - AN ECOLOGICAL STUDY

For two strains, the green alga Pleurococcus CVB4 and the cyanobacteri um Lyngbya CCB2, isolated from the pioneering algal biocoenosis presen t on a marble statue, we determined the optimum range of growth in sel ective cultural media in relation to pH, light intensity, and temperat ure, together with the ability of these organisms to colonize stone su rfaces that differed either in the structure-texture or in the physico -chemical composition of the various lithotypes. The results showed a higher capacity of the green alga to withstand environmental factor ch anges. For both organisms the preferential colonization of the stone s urface was correlated primarily, together with the environmental facto rs (pH, temperature, irradiance), to the physical characteristics (rou ghness and porosity) and secondarily to the chemical composition of th e assayed lithotypes.