Studies on the growth of selected fungal strains on limestones impregnated with silicone resins (Steinfestiger H and Elastosil E-41)

Growth and development of a variety of fungal strains on limestone samples impregnated with the commercially available rock consolidants Steinfestiger H and Elastosil E-41 was studied. It was found that treatment with silicone resins did not prevent fungal growth. On the contrary, growth was, in many instances, more intensive on Elastosil E-41 impregnated stones than on the untreated samples. Using scanning electron microscopy (SEM) it could be demonstrated that growth of mycelia and the sporulation of fungi took place on both freshly prepared rock surfaces and in the interior of the stone, including the films of resin themselves. Some of the fungi growing on treated surfaces caused a significant decrease or the complete loss of the water-repellent properties initially achieved by the impregnant. We could observe that some strains were involved in the degradation of limestone and in apatite biogenesis. The factors stimulating microbial growth on treated rocks are discussed.