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Per- and polyfluoroalkyl substances (PFAS), particularly the perfluorinated ones, are recalcitrant to biodegradation. By integrating a reductively defluorinating enrichment culture with biocompatible electrode materials in an electrochemical system, deeper defluorination of a C6 perfluorinated unsaturated PFAS was achieved compared to the biological or electrochemical system alone. Two types of synergies in the bioelectrochemical system were identified: (i) the microbial-electrochemical in-series defluorination and (ii) the electrochemically enabled microbial defluorination of intermediates at the cathode. Specific cathode microorganisms were enriched, which likely involved in the electrochemically enhanced biodefluorination. The synergies at the material-microbe interface surpassed the limitation of microbial defluorination and further turned the biotransformation end-products into deeper defluorination products, which could be more biodegradable in the environment. It reveals a strong promise of the sustainable material-microbe hybrid system, which could be driven by renewable electricity in PFAS bioremediation and warrants future research to optimize the system and maximize its performance.

Fluorinated organic compounds have emerged as environmental constituents of concern. We demonstrate that the alkane degrader Pseudomonas sp. strain 273 utilizes terminally monofluorinated C7-C10 alkanes and 1,10-difluorodecane (DFD) as the sole carbon and energy sources in the presence of oxygen. Strain 273 degraded 1-fluorodecane (FD) (5.97 ± 0.22 mM, nominal) and DFD (5.62 ± 0.13 mM, nominal) within 7 days of incubation, and 92.7 ± 3.8 and 90.1 ± 1.9% of the theoretical maximum amounts of fluorine were recovered as inorganic fluoride, respectively. With n-decane, strain 273 attained (3.24 ± 0.14) × 107 cells per μmol of carbon consumed, while lower biomass yields of (2.48 ± 0.15) × 107 and (1.62 ± 0.23) × 107 cells were measured with FD or DFD as electron donors, respectively. The organism coupled decanol and decanoate oxidation to denitrification, but the utilization of (fluoro)alkanes was strictly oxygen-dependent, presumably because the initial attack on the terminal carbon requires oxygen. Fluorohexanoate was detected as an intermediate in cultures grown with FD or DFD, suggesting that the initial attack on the fluoroalkanes can occur on the terminal methyl or fluoromethyl groups. The findings indicate that specialized bacteria such as Pseudomonas sp. strain 273 can break carbon-fluorine bonds most likely with oxygenolytic enzyme systems and that terminally monofluorinated alkanes are susceptible to microbial degradation. The findings have implications for the fate of components associated with aqueous film-forming foam (AFFF) mixtures.