28] Studying phototrophic and heterotrophic microbial communities on stone monuments

Abstract

Publisher Summary This chapter discusses the studying of phototrophic and heterotrophic microbial communities on stone monuments. Stone monuments dating back to prehistory and history that is more recent have been built up and decorated with a multitude of materials, the majority of which consisted of rocky and mineral components. Organic compounds have been used, particularly in the case of wall paintings and frescoes, the metabolic activity of microorganisms has resulted in the biomineralization of these types of substrata. Therefore, stone monuments are, in general terms, considered as built up by inorganic materials. In this type of manmade terrestrial environment, most of the organism settlement occurs at the surface and results in the formation of more or less thick biofilms that originate from the development of air-borne cells and spores. However, microbial colonization may produce different patterns and appear as a patchy distribution of ceils that accumulate in fissures, cracks, or in subsurface and deep layers, depending on the porosity and state of conservation of the material as well as on the ecological requirement of individual species. Therefore, according to the distribution on or within the substratum, colonizing microorganisms can be distinguished in epilithobionts and endolithobionts, respectively. This chapter deals with the most recent methodologies that have been applied to the study of phototrophic and heterotrophic microorganisms by researchers working in the field of conservation of cultural heritage.