Antarctic rocks from continental Antarctica as source of potential human opportunistic fungi.

We assessed the diversity of culturable fungi associated with rocks of continental Antarctica to evaluate their physiological opportunistic virulence potential in vitro. The seventy fungal isolates obtained were identified as nine species of Acremonium, Byssochlamys, Cladosporium, Debaryomyces, Penicillium, and Rhodotorula. Acremonium sp., D. hansenii, P. chrysogenum, P. citrinum, P. tardochrysogenum, and R. mucilaginosa were able to grow at 37 °C; in addition, B. spectabilis displayed a high level of growth at 37 and 45 °C. Thirty-one isolates of P. chrysogenum, P. citrinum, and P. tardochrysogenum were able to produce partial haemolysis on blood agar at 37 °C. Acremonium sp., P. citrinum, and P. tardochrysogenum showed spore sizes ranging from 2.81 to 5.13 µm diameters at 37 °C. Of these, P. chrysogenum and P. tardochrysogenum displayed macro- and micro morphological polymorphism. Our results suggest that rocks of the ultra-extreme cold and dry environment of Antarctica harbour cryptic fungi phylogenetically close to opportunistic pathogenic and mycotoxigenic taxa with physiologic virulence characteristics in vitro.