Fungal diversity on archival audio-visual materials

Abstract

The biodeterioration of cultural heritage objects is often attributed to microscopic fungi and their metabolic activity. These fungi often produce pigments that result in aesthetic alterations. Furthermore, through physical mechanisms like hyphal penetration and chemical mechanisms such as the production of acids or other harmful substances, they can degrade the integrity and structure of a wide range of materials. It is therefore necessary to identify these microorganisms as an initial step towards preserving cultural heritage objects for future generations. This study aims to identify the fungi present on audio-visual materials stored in two Czech Republic archives. Employing both a culture-dependent approach, using four different cultivation media, and a culture-independent approach with Illumina MiSeq sequencing, comprehensive fungal identification was conducted. The culture-dependent method yielded the identification of only 11 isolates from 7 genera, highlighting the necessity to enhance fungal capture efficiency, with the MEA medium proving the least suitable. In contrast, 75 genera were identified by the culture-independent approach. However, minimal overlap in results between the approaches, with only the Aspergillus and Bjerkandera genera in common, emphasises the significance of employing both methods. Next, analysis in two different archives suggested a potential association of 16 genera directly with audio-visual materials rather than storage conditions, including the genera Filobasidium, Naganishia, Sporobolomyces, or Wallemia. Furthermore, factors influencing the composition of fungal communities on audio-visual materials were investigated, of which locality proved to be statistically significant.