Diversity and Metabolic Activity of Fungi Causing Biodeterioration of Canvas Paintings

Abstract

Research into the biodeteriorative potential of fungi can serve as an indicator of the condition of heritage items. Biodeterioration of canvas paintings as a result of fungal metabolic activity is understudied with respect to both the species diversity and mechanisms involved. This study brings new evidence for the physiology of fungi biodeteriorative capacity of canvas paintings. Twenty-one fungal isolates were recovered from four oil paintings (The Art Museum, Cluj-Napoca) and one gouache painting (private collection), dating from the 18th to 20th centuries. The species, identified based on the molecular markers Internal Transcribed Spacer (ITS), beta-tubulin (tub2), or translation elongation factor 1 (TEF-1), are common colonisers of canvas paintings or indoor environments (e.g., Penicillium spp., Aspergillus spp., Alternaria spp.). Fungi enzymatic profiles were investigated by means of hydrolysable substrates, included in culture media or in test strips, containing components commonly used in canvas paintings. The pigment solubilisation capacity was assessed in culture media for the primary pigments and studied in relation to the organic acid secretion. Caseinases, amylases, gelatinases, acid phosphatase, N-acetyl-β-glucosaminidase, naphthol-AS-BI-phosphohydrolase, and β-glucosidase were found to be the enzymes most likely involved in the processes of substrate colonisation and breakdown of its components. Aureobasidium genus was found to hold the strongest biodeteriorative potential, followed by Cladosporium, Penicillium, Trichoderma, and Aspergillus. Blue pigment solubilisation was detected, occurring as a result of organic acids secretion. Distinct clusters were delineated considering the metabolic activities detected, indicating that fungi specialise in utilisation of certain types of substrates. It was found that both aged and modern artworks are at risk of fungal biodeterioration, due to the enzymatic activities’ diversity and intensity, pigment solubilisation capacity or pigment secretion.

Uncovering the Fungal Diversity and Biodeterioration Phenomenon on Archaeological Carvings of the Badami Cave Temples: A Microcosm Study

“…These substrates contained components typically encountered in historic canvas paintings. The study revealed that the genus Aureobasidium exhibited the highest level of biodeterioration potential, with Cladosporium, Penicillium, Trichoderma, and Aspergillus following in decreasing order of potential impact [50]. The formation of acid metabolites and solubilization of calcite in the case of fungal isolates indicated probable degradation.…”

The Decorated Garden Grotto of Condes de Basto Palace in Évora, Portugal: Microbial Community Characterization and Biocide Tests for Conservation

“…Ascomycota is one of the most diverse and ubiquitous phylum of eukaryotes, present in numerous ecological habitats [15]. More than 40% of all Ascomycota are lichenized and, according to the literature, as a result of their fungal metabolic activity and ability to hydrolyze short-chain fatty acids, in addition to amylolytic, and occasionally proteolytic and glycolytic activities, most of the fungal species that are involved in the deterioration of cultural heritage belong to this phylum [16,17]. Chlorophyta is a taxon of eukaryotic green algae that often assembles symbiotic relationships with fungi to form lichens.…”

Degradation Potential of Xerophilic and Xerotolerant Fungi Contaminating Historic Canvas Paintings

“…Also, conservation-restoration interventions use preferably organic materials [2]. Nevertheless, there is little information on microbial biodeterioration of these materials [2,3,7,[9][10][11]. Only a few studies so far have focused on the microbial enzymes responsible for degradation of canvas paintings [11][12][13], and they were based on rapid, low-cost plate assays [14,15].…”

“…Nevertheless, there is little information on microbial biodeterioration of these materials [2,3,7,[9][10][11]. Only a few studies so far have focused on the microbial enzymes responsible for degradation of canvas paintings [11][12][13], and they were based on rapid, low-cost plate assays [14,15]. The fungal genera recognized for their broad range of enzymatic activities were Aspergillus, Cladosporium, and Penicillium [14,15].…”

“…The fungal genera recognized for their broad range of enzymatic activities were Aspergillus, Cladosporium, and Penicillium [14,15]. In addition, representatives of the these genera can secrete organic acids and pigments [11,[14][15][16], which can irreversibly change the appearance and structure of canvas paintings [17,18].…”