Till now, a major unsolved question in the environmental chemistry and microbiology is whether microbial defluorination of per- and polyfluoroalkyl substances exist in nature. Due to the strong dissociation energy of carbon-fluorine (C-F) bonds in such fluorinated substances, biological cleavage of the C-F bonds rarely occur. In this presented study, we discovered reductive defluorination of two structure similar per- and polyfluoroalkyl substances in an anaerobic dechlorinating microbial community when the compounds were added as the sole electron acceptor with lactate provided as the primary electron donor, suggesting the presence of organofluoride respiration. By LC-high resolution MS/MS, we elucidated plausible transformation product structures. Moreover, we proposed the underlying biotransformation pathways, including reductive defluorination, hydrogen-fluorine (HF) elimination, hydrogenation, decarboxylation and conjugation reactions. We demonstrated that the reductive defluorination was carried out by other microbial groups than the commonly known dechlorinators <i>Dehalococcoides</i> spp. These findings shed light on both organohalide respiration and global halide cycle, which provide critical fundamental knowledge for future explorations of per- and polyfluoroalkyl substances bioremediation.

Reductive defluorination of per- and polyfluoroalky substances by a dechlorinating microbial community

2019 Fall National Meeting

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