Optimizing a MALDI-TOF MS database for detection of xerophilic fungi across environments

Xerophilic fungi can proliferate in dry and water limited conditions and have been detected in museums, libraries, and other cultural heritage site Xerophilic fungi can proliferate in dry and water limited conditions and have been detected in museums, libraries, and other cultural heritage sites – some despite stringent climate-controlled indoor environments. In order to protect the staff from fungal exposure and ensure the preservation of heritage collections, further research must be placed in improving rapid detection protocols of xerophilic fungi. MALDI-TOF MS provides a fast and efficient method for detection and identification of fungal isolates, however, species identification is highly dependent on the reference database.The aim of this study was to develop a supplementary MALDI-TOFMS database of 19 xerophilic Aspergillus species and use this to complement the current Bruker database, in screening various environments for xerophilic Aspergillus species. These environments included a warehouse, a museum, and 27 domestic homes.The xerophilic Aspergillus species included in the supplementary database, formed species-distinct groups, which also formed clade structures, with similar structures to published phylogeny data based on genomic data. In two environments, xerophilic Aspergillus species were identified using the supplementary database - Aspergillus conicus, Aspergillus dometicus, Aspergillus glabribes, and Aspergillus pseudogracilis. Xerophilic/xerotolerant fungi belonging to the Cladosporium and Penicillium genus, identified using the Bruker library, dominated all environments. Using low water-activity media had a profound effect on growth of these xerophilic Aspergillus species.This work exemplifies the durability and flexibility of using the MALDI-TOF MS platform for detection of specific fungi of interest and is to our knowledge, the first work using the MALDI-TOF MS platform to identify fungi in museums. s – some despite stringent climate-controlled indoor environments. In order to protect the staff from fungal exposure and ensure the preservation of heritage collections, further research must be placed in improving rapid detection protocols of xerophilic fungi. MALDI-TOF MS provides a fast and efficient method for detection and identification of fungal isolates, however, species identification is highly dependent on the reference database.