The chemical structure of fungal melanins and their possible contribution to black stains in stone monuments

Five fungal melanins extracted either from spores, fruiting bodies or culture media, soluble in alkali and precipitated by acid, were characterized by analytical pyrolysis. These melanin fractions were found to be complex mixtures of polysaccharides, proteins, lipids, nucleic acid derivatives and aromatic compounds. The part resistant to either acid hydrolysis or persulphate oxidation represented a small fraction of most of the fungal melanins studied, the exception being those of Aspergillus sydowi and Stachybotrys atra. The possible role of fungal melanins in the formation of black stains on monuments is discussed.