Microbial Cleavage of C‒F Bonds in Per- and Polyfluoroalkyl Substances via Dehalorespiration

Regarding the emerging concerns of the widely occurred and environmentally persistent per- and polyfluoroalkyl substances (PFASs), one intriguing and unsolved scientific question for environmental microbiologists, chemists, and engineers is that whether microbial reductive defluorination of perfluorinated compounds exist in nature. Due to the strong dissociation energy of carbon‒fluorine (C‒F) bonds in PFASs, no convincing evidence for biological cleavage of C‒F bonds from > C₂ perfluorinated structures has ever been reported. We for the first time show C‒F bond cleavage via reductive defluorination by an organohalide-respiring microbial community for two PFASs, perfluoro(4-methylpent-2-enoic acid) and 4,5,5,5-tetrafluoro-4-(trifluoromethyl)-2-pentenoic acid. Comprehensive biotransformation pathways are further elucidated. This study brings valuable fundamental knowledge of microbial dehalorespiration, which opens avenues for the future exploration of PFAS environmental fate and bioremediation strategies.