Biocleaning of wall painting with microbial esterases immobilised in agarart

Biological cleaning of the restored of artworks is a green methodology which avoids the toxicity of solvents used in dry cleaning and protects restorers and environment. Biocleaning with viable bacteria cultures has been used successfully to remove black crust, mineral salts deposits, and organic matter residues, due to selective and specific metabolites proving to be more effective than chemical methods. Biocleaning treatments were applied for removing of the organic materials used in previous restoration or accidentally filed onto an artwork. Gels captured the attention of restorers and their applicability quickly extended to murals, stone, paper, even metals. Agarart hydrogel is recommended both for cleaning of artworks and as a delivery system. This study aimed to remove consolidants (acrylic resin Paraloid B72, Transparent Dispersion of Casein) and accidental organic deposits (beewax, sunflower oil and soot) from the surface of the murals with esterolytic enzymes produced by halotolerant bacteria Bacillus sp. BA N P3.3, applied directly or integrated in Agarart. The experiments were carried out on laboratory models aged by exposure to variations of temperature and humidity respectively to UV-A/UV-B radiation. Although biocleaning was achieved by applying of the esterolytic enzymes entrapped in Agarart gel (E-Agarart) or directly on the surface of organic deposit and then covered with Agarart gel (E+Agarart), to avoid the development of efflorescences, treatment with esterolytic enzymes integrated in Agarart gel is recommended.