Defluorination of per- and polyfluoroalkyl carboxylic acids (PFCAs) by wood decomposer fungi

Large-scale manufacturing and disposal of fluorinated chemicals have led to global pollution by per- and polyfluoroalkyl substances (PFAS) that will require novel remediation techniques and investigation for their environmental fates. Fungi are dominant carbon nutrient recyclers in ecosystems, but their roles in responding to and degrading these persistent fluorocarbons remain largely untapped. Here, we investigated the fungal species' responses to perflouroalkyl carboxylic acid (PFCA) chemicals and their capacities in breaking down C-F bonds for defluorination (deF) by using the ion-selective electrode for quantifying free fluoride anions and the 19F nuclear magnetic resonance (NMR) for monitoring PFAS removal in fungal cultures. Cytotoxicity assays showed that taxa within a unique class of fungi that cause "white rot" type of wood decay have developed an inherent defense mechanism for fluoride and fluorocarbon chemicals, setting off a basis for further investigating their deF phenotype. Although the current test did not evidence clear deF in legacy PFAS, including perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), it identified dehalogenated PFCA structures associated with an electron-attracting alkenyl group that provokes C-F cleavage. Our research, therefore, set a foundation for further unraveling the fungal deF mechanisms, and it also highlighted that future research should give sufficient attention to resident fungal communities in impacted environments due to their potential to recycle fluorinated compounds.