Genetic fingerprint of microorganisms associated with the deterioration of an historical tuff monument in Italy.

Monuments, works of art, and other cultural heritage are affected by microbial colonization that can, togetherwith physical and chemical factors, cause serious structural and aesthetic damage. This is because cultural artifacts provide an inviting range of elements which microorganisms use in their metabolism through biosolubilization, e.g., elements such as calcium, aluminum, silicon, iron and potassium.Microorganisms can induce unsightly discolouration of buildingmaterial and frescoes, formation of pigmented biofilms, biomineralization and degradation of organic binders leading to structural damage (Herrera et al. 2004). Microbial solubilization ofmaterials involves the production of organic and inorganic acids by metabolic activity and is one of the leading biogeochemical mechanisms of rock decay. The bioreceptivity of a stone depends on its structure and chemical composition, air pollutants, moisture, and the varied elemental compositions of the stones provide a suitable environment for the microorganisms to develop. Moreover, phototrophic microorganismsmay grow on the stone surface or may penetrate some millimetres into the rock pore system. These organisms can potentially contribute to the breakdown of rock crystalline structures. With time, the developing microorganisms cause the deterioration of the stones on which they reside by secreting enzymes and activating other metabolic activities by providing a suitable medium for their growth on the stone pores and surfaces (Dornieden et al. 2000;Warscheid and Braams 2000).