Exophiala as a polyextremotolerant fungal model: Ecology, adaptive strategies, and the emergence of “urban oligotrophic specialists”

The genus Exophiala , a group of black yeasts, exemplifies the resilience of polyextremotolerant fungi, which thrive in diverse habitats, including polluted industrial sites, saline waters, and human-associated environments. Characterized by their ability to overcome fluctuations in pH, high salinity, temperature extremes, chaotropic conditions, and nutrient scarcity, Exophiala species serve as models for understanding fungal adaptations to polyextreme conditions. This perspective article reviews current knowledge on the Exophiala genus, highlighting key adaptations, including melanin-mediated protection against radiation and oxidative stress, the emerging role of extracellular vesicles in cellular communication, the influence of polymorphic transitions on environmental resilience and pathogenicity, and the molecular basis of Exophiala 's adaptability and resilience. A central focus of this work is E . dermatitidis , which we propose as a model species for studying fungal adaptation to both natural and anthropogenic environments. Here, we introduce the concept of “urban oligotrophic specialist” to describe E. dermatitidis , emphasizing its ability to thrive in nutrient-limited human-made environments, including kitchens, dishwashers, bathrooms, and hydrocarbon-polluted sites. This unique ecological positioning reflects its adaptation to the Anthropocene, where increasing urbanization, pollution, and climate change are creating novel habitats for fungi. Its thermotolerance, biofilm formation ability, and hydrocarbon metabolism place E. dermatitidis at the intersection of polyextremotolerance and pathogenicity, raising concerns about its potential expansion in response to global environmental challenges. Understanding the biology of the genus Exophiala not only enhances our knowledge of fungal polyextremotolerance but also provides new perspectives into its implications for bioremediation, pathogenicity, and survival in extreme and anthropogenic environments.