Monitoring of Fungal Diversity and Microclimate in Nine Different Museum Depots

Within museum depots, the largest part of all heritage collections is stored. Often, the preservation of highly sensitive objects is an ongoing challenge, as the materials are constantly subjected to and influenced by ever-present environmental factors-above all the surrounding climate and other physicochemical processes. Biological degradation is also a major risk for collections. Fungal infestation poses a particular threat, in many regions increasingly the result of climate change. Models for damage prediction and risk assessment are still underdeveloped and require a more substantial database. Approaching this need, nine museum depots and archives were selected in this study. Two years of monitoring the indoor microclimate with thermohygrometric sensors, investigating fungal abundance and diversity through culture-dependent and -independent (metagenomics) approaches, and the collection of relevant additional information resulted in a vast amount of diverse data. The main fungal genera identified through cultivation were Cladosporium, Penicillium, Aspergillus, Alternaria and Epicoccum. The cultivation-independent approach identified Aspergillus, Pyronema, Penicillium, Xenodidymella and Blumeria as the main taxa. Data analyses indicated that key drivers involved in similarities, patterns and differences between the locations were their geographic location, immediate outdoor surroundings and indoor (micro)climatic fluctuations. The study also sheds light on a possible shift in focus when developing strategies for preventing mold growth in collection depots beyond the prevailing path of tightest possible climate control.