Poorly known microbial taxa dominate the microbiome of permafrost thaw ponds. Permafrost_thaw_ponds

In the transition zone of the shifting permafrost border, thaw ponds emerge as hotspots of microbial activity, processing the ancient carbon freed from the permafrost. We analysed the microbial succession within a gradient of 12 emerging to old ponds, for which we applied one universal, one bacterial, and one fungal molecular marker. Age was a major modulator of the microbial community of the thaw ponds. Surprisingly, typical freshwater taxa comprised only a small fraction of the community, while thaw ponds of all age classes were dominated by enigmatic bacterial and fungal phyla. Our results on permafrost thaw ponds lead to a revised perception of the thaw pond ecosystem and their microbes, with potentially far-reaching implication for carbon and nutrient cycling.