Multifaceted Assessment of Fungal Diversity and Biodegradation Activity in Historical Library

Historical books are an irreplaceable part of cultural heritage. Unfortunately, their constituent materials are highly susceptible to microbial colonization, especially by fungi, which commonly leads to deterioration through growth and metabolic activity. This process, characterized by changes in color and texture culminating in material decomposition, is responsible for incalculable losses. This study investigated fungal communities present in the National Library of the Czech Republic, analyzing both book-associated fungi (blocks and covers) and airborne fungi through complementary approaches: culture-dependent methods utilizing multiple media (MEA, PDA, SDA, YGC) and culture-independent DNA/RNA-based Illumina MiSeq sequencing. An integral part involved assessing the degradation potential of the most prevalent isolates to determine their threat to the books. The culture-dependent analysis revealed Penicillium, Aspergillus, and Cladosporium as predominant genera across all media in both air and book samples. While no significant differences were observed between media types, each captured unique genera, making their combined use essential for comprehensive community analysis. The culture-independent sequencing identified additional abundant taxa, notably Cryptococcus and Saccharomyces, in both sample types. Despite the distinct properties of the examined cover materials (leather, textile, paper), no significant differences in fungal communities were observed. Further analysis revealed that while each environment maintained its unique populations, 15 genera were shared across all sample types. Enzymatic assays demonstrated widespread cellulolytic, amylolytic, and proteolytic capabilities, particularly among Penicillium and Aspergillus species, which also demonstrated remarkable adaptability to diverse nutrient conditions. Notably, culture-dependent methods identified a wider range of genera than molecular approaches, challenging common assumptions about detection capabilities.