RESUMEN
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-ß-glucosaminidase, naphthol-AS-BI-phosphohydrolase, and ß-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.
RESUMEN
The study of the physiological action of microorganisms in artistic materials is one of the most interesting topics in biodeterioration nowadays. Pathologies and illnesses of organic and inorganic materials provoked by microorganisms can be treated by experts by a variety of preventive interventions. Artistic medicine encompasses the monitoring of the exhibition and storage of art, as well as proper environmental conditions and the regular cleaning of museums. Biodeterioration control is essential in order to prevent fungal and bacterial contamination in artwork. Biodeterioration of canvas paintings is a complex phenomenon, not well-known at the moment. Canvas paintings are created by several artistic techniques on textile supports that are not always kept in the best conditions, and the best parameters of preventive conservation are often not applied. Therefore, we need to research the agents and the main causes that provoke canvas painting biodeterioration. By applying new methodologies, we can identify the alterations and the treatments needed in order to manage the diverse materials employed in artwork correctly. Herein, we review the causes of biodeterioration that affect artwork, especially art created on textile supports. We also study the alterations of the natural filmogenic materials employed in traditional pictorial techniques, such as agglutinants and protection layers, and the biodeterioration agents that impact them. Additionally, we review current scientific methods employed for the identification of microbial species, and the types of alterations of the materials where the organisms grow. Finally, we summarize the different biocides and preventive conservation treatments that are currently employed.