Polyfluoroalkylether substances (ether PFAS) are widely detected in the environment with limited knowledge of their environmental fate via biological processes. This study reports the microbial transformation of environmentally relevant ether PFAS and similar structures and important microbial groups involved in the anaerobic biotransformation process. The investigated ether PFAS include mono- and dichlorinated ones such as 6:2 chlorinated polyfluorooctane ether sulfonate (F53-B) and 6,7-dichloroperfluoro-5-oxaheptanoic acid, as well as unsaturated ones such as sodium p-perfluorous nonenoxybenzenesulfonate (OBS) and the Nafion Byproduct 1 (NBP1). The presence of chlorine-substitution and unsaturated carbon facilitated the biotransformation and defluorination of ether PFAS under anaerobic or aerobic conditions. For fully halogenated ether PFAS, biotransformation only occurred in anaerobic conditions via dechlorination (reductive, eliminative, and hydrolytic), hydrolytic O-dealkylation, and reductive defluorination, forming less fluorinated and shorter chain products. Strong evidence was obtained from community and pure culture experiments for the involvement of cobalt-enzyme-dependent microorganisms, such as Sporomusa sphaeroides, in the initial dechlorination step during the biotransformation of chlorinated ether PFAS. Meanwhile, microorganisms independent of cobalt-enzymes, such as Desulfovibrio aminophilus, were responsible for the biotransformation of non-chlorinated unsaturated ether PFAS (e.g., NBP1), especially for the hydrolytic O-dealkylation reaction. The findings provide significant insights of the fate of ether PFAS in anaerobic environments and underscore the cooperation of different microbial groups in a community to achieve further transformation and higher defluorination.

中文翻译：

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多氟烷基醚物质（醚 PFAS）的厌氧微生物脱氟：不同微生物的转化途径和作用


多氟烷基醚物质（醚 PFAS）在环境中被广泛检测到，但对其通过生物过程的环境归宿了解有限。本研究报告了环境相关醚 PFAS 和类似结构的微生物转化，以及厌氧生物转化过程中参与的重要微生物群。研究的醚类 PFAS 包括单氯和二氯类 PFAS，如 6：2 氯化多氟辛烷醚磺酸盐 （F53-B） 和 6,7-二氯全氟-5-噁庚酸，以及不饱和类 PFAS，如对全氟壬氧苯磺酸钠 （OBS） 和 Nafion 副产品 1 （NBP1）。氯取代和不饱和碳的存在促进了醚 PFAS 在厌氧或好氧条件下的生物转化和脱氟。对于全卤醚 PFAS，仅在厌氧条件下通过脱氯（还原、消除和水解）、水解 O-脱烷基化和还原脱氟发生生物转化，形成氟化程度较低且链更短的产品。从社区和纯培养实验中获得强有力的证据，证明钴酶依赖性微生物（如球形孢子藻）参与氯化醚 PFAS 生物转化过程中的初始脱氯步骤。同时，独立于钴酶的微生物，如嗜氨基脱硫菌，负责非氯化不饱和醚 PFAS（如 NBP1）的生物转化，尤其是水解 O-脱烷基化反应。 这些发现为醚 PFAS 在厌氧环境中的命运提供了重要见解，并强调了社区中不同微生物群的合作，以实现进一步的转化和更高的脱氟作用。