Impact of a mixture of PFAS molecules on the activity and structure of soil microbial communities

PFAS compounds have emerged as a major concern, due to their effects on human health, widespread occurrence, complex physico-chemical behaviour, very low biodegradability and lack of removal/degradation technologies that could be effective for the very diverse members of this huge family of molecules. Unlike other organic compounds released in environment by anthropogenic activities, such as petroleum hydrocarbons, polychlorinated biphenyls or pesticides, PFAS compounds concentration in the environment is at the parts-per-billion (ppb) and parts-per-trillion (ppt) levels. As a consequence, the microbial communities of most environmental compartments were not exposed to high doses of PFAS, their adaptation strategies largely remain to be explored. They could give useful clues for a better description of the impacts of these molecules and for the development of models of their fate in environment including the biological compartment. Here, 4 different soils presenting contrasting physico chemical properties were artificially contaminated by a mixture of 4 PFAS molecules (PFOS, PFOA, PFHxS and PFBS), in concentrations fixed at 10 mg.kg-1 each and incubated. The impact of PFAS addition was monitored on carbon mineralization activity, enzymatic activities, and evolution of the structure and composition of bacterial, archaeal and fungal communities during 70 days of incubation. The PFAS concentrations were not significantly modified during the incubation, but the mixture of PFAS molecules affected the structure and activity of soil microbial communities differently depending on the type of soil.