Riding the wave: Response of bacterial and fungal microbiota associated with the spread of the fairy ring fungus Calocybe gambosa

The regular configuration of fungal basidiomycetous fronts in fairy rings allows a thorough scrutiny of associated soil changes. Here, we studied the soil chemistry and the microbiota modifications induced by the passage of Calocybe gambosa fairy rings in a botanical garden. Significant changes in soil physicochemical properties and microbiota were observed in correspondence of active fungal mycelium, where an accumulation of nutrients, an increase in hydrophobicity, and a decrease in pH were recorded. In addition, on one hand, a sharp decline of fungal diversity in soil occurred in association with C. gambosa colonization. On the other hand, the bacterial community showed a variable taxon-specific response, with taxa within Bacteroidetes and Proteobacteria being able to thrive in association with C. gambosa.