Cometabolic defluorination of two poly-fluoroalkyl substances by a new Sphingopyxis isolate.
Gao Z, Xiang X, Yan M, Liu Y, Wu Y
Summary
2.8/10Researchers discovered a bacterium that can break down PFAS, persistent synthetic chemicals that pollute soil and groundwater. By identifying the right nutrients to stimulate microbial growth, scientists showed the organism efficiently removes fluorine from these harmful compounds, potentially offering a cost-effective biological approach to remediating contaminated sites.
Key Findings
Sphingopyxis sp. strain NJF-3 released 873 ± 55 μM fluoride from 1 mM fluorodecane within 7 days
3,3-dimethylacrylic acid enhanced TFEA defluorination with 27.3 ± 1.8 μM removal and 71 ± 2.7 μM F⁻ release over 28 days
PFAS degradation proceeds via β-oxidation pathway with hydroxylation-dehydration steps critical for C-F bond cleavage
Original Abstract
Microbial defluorination of per- and poly-fluoroalkyl substances (PFAS) likely involves cometabolic degradation. The isolation of pure cultures capable of this cometabolism would enhance our understanding of microbial defluorination mechanisms. Here, a novel isolate Sphingopyxis sp. strain NJF-3 was isolated and used to investigate the cometabolic defluorination of two poly-fluoroalkyl substances, 4,5,5-trifluoropent-4-enoic acid (TFEA) and 4,4,4-trifluoro-3-(trifluoromethyl)crotonic acid (SFCA). The isolate utilized 1-fluorodecane (FD) as the sole carbon source and released 873 ± 55 μM of inorganic fluoride (F⁻) from 1 mM FD within a 7-day incubation. The cometabolism of TFEA and SFCA by strain NJF-3 were significantly dependent on bacterial growth. Eleven cometabolic substrates were tested, revealing that 3,3-dimethylacrylic acid significantly stimulated TFEA defluorination, resulting in the removal of 27.3 ± 1.8 μM TFEA and the release of 71 ± 2.7 μM F⁻ over 28 days of incubation. Ammonium acetate promoted SFCA defluorination, leading to the degradation of 183 ± 17 μM SFCA and the release 736 ± 8.3 μM of F⁻ following 60 days of incubation. The integration of intermediate analysis with genomic data of strain NJF-3 revealed that the cometabolic biodefluorination proceeds via β-oxidation pathway, with hydroxylation-dehydration steps likely crucial for enzymatic C-F bond cleavage.