EXCRETION OF ORGANIC-ACIDS BY FUNGAL STRAINS ISOLATED FROM DECAYED SANDSTONE

A study of the presence of fungi on weathered sandstone from the Churc h of Carrascosa del Compo (Spain) was accomplished. Fungi were test fo r their capacity for excreting organic acids when cultured in Czapek-D ox broth as well as in the presence of algal biomass. Strains of the g enera Penicillium and Fusarium excreted oxalic, fumaric and succinic a cids with corrosive effects on the stony materials. Moreover, P. coryl ophilum was able to produce oxalic acid when cultured in the presence of the algae M. braunii as the only source of carbon and nitrogen. S.E .M. observations showed that fungal spores inoculated together with al gal biomass on sand-stone cubes, germinated and resumed a regular grow th.