Biodeteriogenic fungi isolated from historic window glass in Certosa di Pavia (Italy).

Fungi use, above all, organic matter but it appears that they can also degrade inorganic matter such as stone or glass. The aim of our research was to detect mycofl ora present on three of the historical windows located in the famous monastery complex of Certosa di Pavia, built between 1436 and 1507, and to evaluate the biodeterioration activity of the isolated strains. A total of 31 fungal strains was identified. Ten strains were tested on a saline medium (Czapeck) dosed with four different calcium carbonate concentrations. Three of them (Aspergillus ochraceus, A. niger and Eurotium herbariorum) were able to transform completely the calcium carbonate into two different crystal forms of calcium oxalate( whewellite and weddellite). Microscopial investigations by SEM have shown that all the tested species were able to grow on the glass model samples and to produce many crystalline forms of calcium oxalate, but none caused any kind of crack. We hypothesise that strains able to dissolve calcium carbonate in vitro could be responsible in the long term for glass cracking.