Fungal representation in the environment of penguin communities in the French Southern territories.

Penguins are highly susceptible to airborne mycoses, and aspergillosis due to Aspergillus fumigatus (recently classified as priority pathogen by WHO) is common in captivity; however, environmental fungal diversity and exposure risk in natural, non-temperate breeding habitats remain poorly described. We aimed to characterize the seasonal burden and diversity of culturable fungi in wild king penguin (Aptenodytes patagonicus) colonies and to assess A. fumigatus diversity and phenotypes. During one year, monthly environmental sampling was performed from four different soils of Crozet archipelago, in French Southern Territories, around three penguin colonies. Samples were cultured on malt extract agar at 35 ± 2°C. Isolates were quantified (CFU) and identified by microscopy, MALDI-TOF MS, and DNA sequencing. A. fumigatus isolates underwent genotyping and phenotyping for antifungal susceptibility, as well as for tolerance to high salinity and extreme temperatures. Overall, fungal loads in penguin environments showed marked seasonality (3-1 100 CFU/month), peaking during breeding/chick rearing summer period (∼22% positive sites). After April, fungal burden declined (mean 150 CFU/month; 8.8% positive sites). Aspergillus section Fumigati represented 21-100% of isolates (150-950 CFU/month). A. fumigatus genotypes were diverse, with no detected antifungal resistance or extreme growth phenotypes. Fungal burden in penguin natural habitats was closely linked to bird presence and breeding activity. These findings provide new insights into fungal exposure in wild groups and emphasize the importance of a One Health approach to better understand the interactions between environment, wildlife, and infectious disease risk in fragile ecosystems.