The Control of Cultural Heritage Microbial Deterioration

Abstract

The microbial deterioration of cultural heritage includes physical and chemical damage as well as aesthetic alteration. With the technological advancement, a plethora of techniques for removing unwanted microorganisms have opened up new opportunities for microbiologists and conservators. This article reviews the most applied, up-to-date, and sustainable techniques developed for the control of cultural heritage microbial deterioration presenting noteworthy case studies. These techniques include chemical methods, i.e., traditional biocides and nanoparticles; physical methods, such as mechanical removal, UV irradiation, gamma radiation, laser cleaning, heat shocking, microwaves, and dry ice treatment; and biological methods, such as natural molecules with biocidal activity, enzymes, and microorganisms. The application of control systems requires the comprehension of their behavior toward the unwanted microorganisms and possible interactions with the heritage materials. This overview shows also the control methods drawbacks for the purpose of creating awareness in selecting the most suitable technique or combination of techniques.

UV-C Irradiation as a Tool to Reduce Biofilm Growth on Pompeii Wall Paintings

“…The chemical compounds normally used to inhibit the proliferation of stone colonizing microorganisms, although harmless for the surfaces of interest, may pose a serious threat to the surrounding ecosystems. In fact, these biocides are characterized by a long durability, which, together with the phenomenon known as “lixiviation” (i.e., water running on stone surfaces extracting these compounds and depositing them into water ways), makes them harmful for the environment [ 7 ].…”

“…The first experimentations of this method were carried out in 1995, both on mural paintings [ 29 ] and on mosaics [ 30 , 31 ], but ultimately disregarded until several years later when subsequent experimentations were carried out by French research teams on specimens collected from the lampenflora of Dordogne caves [ 3 , 5 , 7 , 21 ].…”

“…In fact, UV-C irradiation has been applied to stone surfaces as early as the 1960s; Dobatenvis used ultraviolet rays to remove the phototrophic microorganisms; later Borderie et al 2011 [ 5 ] showed that UV-C treatment is useful in the elimination of biofilm in caves. Pfendleret al [ 6 ] indicated that in situ UV-C treatment is efficient, faster, cheaper, and more environmentally friendly when compared to chemicals [ 7 ]. Recently, a renewed attention towards some cave paintings found inside caverns located in South-Western France has led to the installation of UV-C lamps for conservative purposes [ 3 , 5 , 7 ].…”

“…Pfendleret al [ 6 ] indicated that in situ UV-C treatment is efficient, faster, cheaper, and more environmentally friendly when compared to chemicals [ 7 ]. Recently, a renewed attention towards some cave paintings found inside caverns located in South-Western France has led to the installation of UV-C lamps for conservative purposes [ 3 , 5 , 7 ]. Not unlike the French caves, Pompeii also represents an ideal condition for the development of autotrophic biofilms, being an archaeological site with variable atmospheric conditions, exposure to artificial lighting and the almost daily presence of visitors.…”

The Application of the Essential Oils of Thymus vulgaris L. and Crithmum maritimum L. as Biocidal on Two Tholu Bommalu Indian Leather Puppets

“…These products are usually toxic for humans and the environment. Hence, in the last decade, essential oils have been applied in order to combat cultural heritage biodeterioration as an eco-friendly solution [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. To prevent biodeterioration caused by fungi and bacteria, objects must first be disinfected.…”