Identifying specialisation of pathogenic trade-offs in metacommunities of fungi exposed to pentachlorophenol

The impacts of man-made chemicals, in particular of persistent organic pollutants, are multifactorial as they may affect the integrity of ecosystems, alter biodiversity and hinder the health of most organisms. We have demonstrated previously that the belowground mycobiota of forest soils acts as a buffer against the pollution provoked by the biocide pentachlorophenol. However the trade-offs of the mitigation of the pollutant remain cryptic. To address this question we scrutinised the key changing aspects of a metacommunity of fungi when confronted (or not) with the biocide, comprising taxonomic and functional levels, as well as the identification of the major pollutant degraders within the metacommunity. Exposure to the biocide led to alterations in the metacommunity composition and functioning, many of which were not fully alleviated when most of the biocide was degraded, especially the dysregulation of the carbon and nitrogen metabolisms. The last is possibly linked to the higher pathogenic potential of the metacommunity after exposure to the biocide, supported by the secretion of proteins related to pathogenicity and reduced susceptibility to a standard fungicide. Our findings provide additional evidence for the silent risks of environmental pollution, particularly as it may favour the development of pathogenic trade-offs in fungi, which may impose serious threats to animals and plant hosts.