Documentary heritage: fungal deterioration in Compact Discs

Abstract

In recent years, there has been an exponential growth in the use of digital media for data storage and the creation of museums, libraries and digital archives. In particular, Compact Discs Recordable (CD-R) have become one of the most used tools for archiving documents related to cultural heritage. Many authors have investigated only the CD longevity, but very few studies have focused on their biological deterioration. The aim of this work was to examine the CD-R biodeterioration following two ways: (1) search badly preserved CD-R, showing clear degradation spots and verify that it is fungal deterioration; (2) fungal inoculation tests on blank CD-R to verify their bioreceptivity. The analysis of a badly preserved CD-R showed clear degradation spots, highlighting, after cultural and molecular analysis, the presence on the surface of three different fungi: Chaetomium globosum, Trichoderma atroviride e Coniochaeta sp. For the in vitro inoculation tests we used conidia suspensions of Cladosporium cladosporioides and Penicillium chrysogenum, and we observed the growth for 6 months. At the end of experiment, both fungi colonized the CD-R surface with hyphae and mycelia clearly visible, causing also loss of material and fractal structure presence. For the CD-R use as cultural heritage archiving, the correct storage is an essential phase and, in light of the results obtained, it will be necessary not only to consider the environmental factors (temperature, relative humidity) but also the biological deterioration caused by airborne fungi. Therefore, effort needs to be taken to regularly monitor temperature and relative humidity and it is essential to periodically conduct cleaning of optical media.