Changes in the soil bacterial community across fairy rings in grasslands using environmental DNA metabarcoding

Fairy ring fungi are considered keystone species in grasslands due to their strong impact on soil physicochemical properties, but their effect on the associated bacterial community is poorly understood. Here, we analyze shifts in soil bacterial diversity and community composition across fairy rings using Illumina metabarcoding. A total of 254,135 MiSeq reads and between 405 and 1444 operational taxonomic units (OTUs) per soil sample were observed in a montane grassland in the Eastern Pyrenees. We found a strong reduction in all bacterial diversity indices inside the ring-affected zones compared to the outside grassland, especially in the stimulation (current ring) zone. The exception were Firmicutes, the dominant taxa in the grassland, which increased their relative abundance further in fairy ring-affected zones. The recovery of bacterial populations after the fungal front passage highlights the strong resilience of the bacterial communities to this biotic disturbance.