Influence of several metabolites excreted by microorganisms on building stone deterioration

Abstract

One of the most important weathering factors of building stone, besides the meteorological phenomena (rain, snow, drought, hail…) is the biodeterioration produced by micro-organisms. In situations of water stress or extreme temperatures, microorganisms respond with the excretion of several metabolites that can affect stone. The effect of some metabolites (citric acid, ascorbic acid, oxalic acid, glucose and glycerol) has been evaluated on two types of stone with dissimilar porosity, limestone and Macael marble. The samples have been subjected to several cycles of exposure to metabolites, followed by freezing and desiccation as well as other cycles without exposure. The deterioration of the stones has been quantitatively evaluated by physical properties (bulk density, porosity, absorption and capillary water absorption). This study has concluded that deterioration depends on the nature of the stone, the presence or absence of metabolite and its chemical nature. The control of microorganisms present on building stone is essential for its conservation.