Microbes Degrading History: A 50-Year Systematic Review of Microbial Threats to Archival Documentary Heritage

This work critically examines studies of microbial threats in archival environments and their consequences. The literature search was conducted in three scientific databases and included publications from 1975 to 2025. After applying the eligibility criteria, 32 interdisciplinary studies were grouped into five categories: microbial characterization of documentary media (11), environmental monitoring (6), combined approaches (10), health risks (2), and preservation innovations (3). The studies analyzed air and documentary media samples, mainly paper-based and cellulosic materials, and correlated biodeterioration with physicochemical, thermohygrometric, and microbiological parameters using culture-dependent and culture-independent methods. Nine categories of damage and related phenomena were identified. Although 209 taxa were reported, the diversity documented varied among studies and was influenced by seasonal conditions. The most frequently reported potentially biodeteriogenic microorganisms included bacteria (Bacillus, Staphylococcus, and Streptomyces) and fungi (Penicillium, Aspergillus, Cladosporium, Alternaria, and Fusarium), some of which may have clinical relevance. Thermohygrometric parameters were key factors associated with microbial colonization, reinforcing the importance of environmental monitoring, hygiene protocols, and preventive conservation strategies.