Back to the past—forever young: cutting-edge biochemical and microbiological tools for cultural heritage conservation

Abstract

Ancient documents and milestones of human history such as manuscripts and textiles are fragile and during aging undergo chemical, physical, and biological deterioration. Among the different causes of damage, also human intervention plays a role since some restoration strategies proved to be transient and/or they generated further damage. Outdoor monuments undergo deterioration since they are exposed to pollution, weathering, microbial attack (giving rise to undesired pigmentation, discoloration or true dissolution, corrosion, and overall decay), as well as man-made damage (i.e., graffiti). This review article reports the best-fitting strategies used to restore wall paintings, outdoor monuments, textiles, and paper documents to their ancient beauty by employing "soft" biobased approaches such as viable bacteria or suitable enzymes.

Ancient Textile Deterioration and Restoration: Bio-Cleaning of an Egyptian Shroud Held in the Torino Museum

“…Agents Humidity and relatively high temperatures favor the growth of microbial species, both bacteria and fungi, thus opening the way for release of molecules that can damage textiles (Mazzoli et al 2018b). Among them, catabolites (surfactants, solvents, acids), secondary metabolites (pigments) and enzymes (proteases, lipases, and glycosidases) play a major role.…”

“…The idea of using an enzyme-enriched poultice was developed to treat starch-damaged paper materials (Schwarz et al 1999) and successfully translated to textiles. As far as enzyme immobilization is concerned, it has to be underlined that preliminary tests should be performed to evaluate (i) the immobilization yield (amount of enzyme really attached to the chosen surface); (ii) the catalytic activity after immobilization (K m , V max , K cat ); and (iii) the overall efficacy of the immobilized system to remove glue (Ferrari et al 2017;Mazzoli et al 2018b).…”

Biocleaning of starch glues from textiles by means of α-amylase-based treatments

“…Glues based on starch, collagen or casein have been widely used to consolidate brittle fibres in historic and archaeological textiles. However, these glues tend to undergo hydrolysis/oxidation and crosslinking reactions, becoming insoluble and leading to discoloration, biodeterioration, and formation of cracks and tensions in the fibres (Mazzoli et al 2018). For the preservation of textile artefacts, therefore, it is essential to remove completely aged consolidants and glues.…”

“…For the preservation of textile artefacts, therefore, it is essential to remove completely aged consolidants and glues. In this context, the hydrolytic action of enzymes is very promising, as they exhibit great selectivity in the cleaning of unwanted materials, without compromising the historic and artistic substrates (Bosch-Roig and Ranalli 2014;Cremonesi 2013;Decoux 2002;Mazzoli et al 2018;Palla and Barresi 2017). Due to their negligible toxicity, their use as substitutes of organic solvents is widely reported on different substrates, such as wall paintings (Beutel et al 2002;Ranalli et al 2005), paintings on canvas (Pereira et al 2013), paper (Decoux 2002;Mazzuca et al 2014Mazzuca et al , 2017Schwarz et al 1999), textiles (Ahmed and Kolisis 2011;Bott 1990;Chapman 1986;Ferrari et al 2017;Shibayama and Eastop 1996), stones (Valentini et al 2010(Valentini et al , 2012, and acrylic-based graffiti and coatings (Bellucci et al 1999;Germinario et al 2017).…”

Immobilized Enzymes on Gold Nanoparticles: From Enhanced Stability to Cleaning of Heritage Textiles

“…Current research focuses on the development of innovative cleaning materials, including microemulsions, solvents and rigid gels [12][13] , and biological cleaning methods such as microorganisms and hydrolytic enzymes. [14][15][16][17][18][19] Enzymes exhibit exquisite molecular recognition 15,[19][20] , and have been used to remove starch paste 18,[21][22][23] , protein-based glues and adhesives 18,24 , lipid-based compounds 25 , and aged acrylic coatings and inks 26 from historic textiles, paper and prints, wall-paintings and ceramic materials.…”