Household Appliance Seals as Niches for Fungal Growth: The Role of Anthropogenic Factors and Appliance Age

Household appliances may serve as reservoirs of fungi, including species pathogenic to humans. The present study aimed to characterize the diversity of fungal communities inhabiting the door seals of 40 household appliances (refrigerators, dishwashers, and washing machines). Fungi were cultured using two media, three temperatures and identified by phenotypic and molecular methods. Incubation temperature was a key factor in the efficiency of fungal isolation. The highest species richness (n = 23) was achieved at 25°C, while 37°C resulted in lower efficiency (n = 10). The choice of culture medium allowed for the recovery of a comparable number of species. The results revealed distinct fungal communities associated with different types of appliances, dominated by Ascomycota fungi (including the genera Penicillium , Aspergillus , and Cladosporium ) and identified several fungal species of potential clinical significance (e.g., Aspergillus fumigatus , Cladosporium halotolerans , and Rhodotorula mucilaginosa ). Overall, thirty-one fungal species were obtained, and the highest number was recovered from refrigerators (n = 25), whereas the lowest was detected in dishwashers (n = 8). Additionally, the relationships between appliance characteristics and fungal contamination were evaluated. Overall, no significant correlations were detected, with the exception of refrigerators, where the number of fungal species decreased with increasing frequency of use (r = -0.71, p < 0.001) and shorter time since last use (r = -0.64, p < 0.001). These findings expand current knowledge of fungal communities inhabiting domestic environments and highlight the need for research on effective decontamination strategies to reduce microbial exposure in households.