Enzymatic bioremediation of cultural heritage materials stained with organic pigments.

Bio-cleaning technologies utilizing enzymes are used in restoration of historical artifacts and monuments. Darkening of stones, paintings, tissues and papers surfaces is frequently due to the presence of melanin produced by Aspergillus niger, under high humidity conditions. Melanin is a brown pigment, with a high molecular weight, insoluble in water and many organic solvents. Studies about melanin degradation have been performed in buffered solutions, at different pH and temperature, utilizing the laccase, enzyme produced by white rot fungi. Results show that 25°C and pH 6 are the best operating conditions for a reduction (36%) of melanin.