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Skinner JP, Raderstorf A, Rittmann BE, Delgado AG. Biotransforming the "Forever Chemicals": Trends and Insights from Microbiological Studies on PFAS. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2025; 59:5417-5430. [PMID: 40067878 PMCID: PMC11948467 DOI: 10.1021/acs.est.4c04557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 01/14/2025] [Accepted: 01/29/2025] [Indexed: 03/26/2025]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are recalcitrant contaminants of emerging concern. Research efforts have been dedicated to PFAS microbial biotransformation in the hopes of developing treatment technologies using microorganisms as catalysts. Here, we performed a meta-analysis by extracting and standardizing quantitative data from 97 microbial PFAS biotransformation studies and comparing outcomes via statistical tests. This meta-analysis indicated that the likelihood of PFAS biotransformation was higher under aerobic conditions, in experiments with defined or axenic cultures, when high concentrations of PFAS were used, and when PFAS contained fewer fluorine atoms in the molecule. This meta-analysis also documented that PFAS biotransformation depends on chain length, chain branching geometries, and headgroup chemistry. We found that the literature is scarce or lacking in (i) anaerobic PFAS biotransformation experiments with well-defined electron acceptors, electron donors, carbon sources, and oxidation-reduction potentials, (ii) analyses of PFAS biotransformation products, and (iii) analyses to identify microorganisms and enzymes responsible for PFAS biotransformation. To date, most biotransformation research emphasis has been on 8:2 fluorotelomer alcohol (8:2 FTOH), 6:2 fluorotelomer alcohol (6:2 FTOH), perfluorooctanesulfonic acid (PFOS), and perfluorooctanoic acid (PFOA). A wide array of PFAS remains to be tested for their potential to biotransform.
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Affiliation(s)
- Justin P. Skinner
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, Arizona 85287, United States
- Center
for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, Arizona 85281, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, Arizona 85281, United States
| | - Alia Raderstorf
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, Arizona 85287, United States
- Center
for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, Arizona 85281, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, Arizona 85281, United States
- Natural
Resource Conservation Service, U.S. Department
of Agriculture, 1585
S Plaza Way #120, Flagstaff, Arizona 86001, United States
| | - Bruce E. Rittmann
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, Arizona 85287, United States
- Center
for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, Arizona 85281, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, Arizona 85281, United States
| | - Anca G. Delgado
- Biodesign
Swette Center for Environmental Biotechnology, Arizona State University, 1001 S McAllister Ave, Tempe, Arizona 85287, United States
- Center
for Bio-mediated & Bio-inspired Geotechnics, Arizona State University, 425 E University Dr, Tempe, Arizona 85281, United States
- School
of Sustainable Engineering and the Built Environment, Arizona State University, 660 S College Ave, Tempe, Arizona 85281, United States
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Huang S, Pilloni G, Key TA, Jaffé PR. Defluorination of various perfluoro alkyl acids and selected PFOA and PFOS monomers by Acidimicrobium sp. Strain A6 enrichment cultures. JOURNAL OF HAZARDOUS MATERIALS 2024; 480:136426. [PMID: 39531816 DOI: 10.1016/j.jhazmat.2024.136426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2024] [Revised: 10/08/2024] [Accepted: 11/05/2024] [Indexed: 11/16/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) have emerged as a diverse class of environmental pollutants, garnering increasing attention due to their various structural types and potential ecological impacts. The impact of select PFAS on environmental microorganisms and the potential for microbial degradation of certain PFAS are timely research topics. In this study, we conducted a series of batch incubation to investigate the effects of C4-C10 perfluoroalkyl carboxylic acids (PFCAs) and perfluorosulfonic acids (PFSAs), as well as linear and branched perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) monomers, on the Feammox reaction and Acidimicrobium sp. A6 (A6), a microbe known to degrade PFOA and PFOS. We explored the defluorination ability of A6 cultures with these PFAS, evaluating their response to varying chemical structures. While A6 cultures demonstrated the ability to degrade a wide range of PFAAs (11.5-56.9 % reduction over 120 days), challenges were noted with specific compounds like PFPeA and double-branched PFCAs and PFSAs, which also showed reduced ammonium removal. Additionally, exposure to the selected PFAS resulted in notable shifts in the microbial community within the A6 enrichment cultures, indicating a selective pressure that benefits certain strains (e.g., increased percentages of Acidimicrobium, Paraburkholderia, and Desulfosporosinus in several PFCA, PFSA and PFOA/PFOS monomers enriched cultures). These insights contribute to our understanding of microbial-PFAS interactions and are instrumental in developing bioremediation strategies for PFAS-impacted environments.
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Affiliation(s)
| | - Giovanni Pilloni
- ExxonMobil Technology and Engineering Company, United States; ExxonMobil Environmental and Property Solutions Company, United States
| | - Trent A Key
- ExxonMobil Biomedical Sciences Inc., United States
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Yu Y, Xu F, Zhao W, Thoma C, Che S, Richman JE, Jin B, Zhu Y, Xing Y, Wackett L, Men Y. Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp. SCIENCE ADVANCES 2024; 10:eado2957. [PMID: 39018407 PMCID: PMC466959 DOI: 10.1126/sciadv.ado2957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 06/12/2024] [Indexed: 07/19/2024]
Abstract
Enzymatic cleavage of C─F bonds in per- and polyfluoroalkyl substances (PFAS) is largely unknown but avidly sought to promote systems biology for PFAS bioremediation. Here, we report the reductive defluorination of α, β-unsaturated per- and polyfluorocarboxylic acids by Acetobacterium spp. The microbial defluorination products were structurally confirmed and showed regiospecificity and stereospecificity, consistent with their formation by enzymatic reactions. A comparison of defluorination activities among several Acetobacterium species indicated that a functional fluoride exporter was required for the detoxification of the released fluoride. Results from both in vivo inhibition tests and in silico enzyme modeling suggested the involvement of enzymes of the flavin-based electron-bifurcating caffeate reduction pathway [caffeoyl-CoA reductase (CarABCDE)] in the reductive defluorination. This is a report on specific microorganisms carrying out enzymatic reductive defluorination of PFAS, which could be linked to electron-bifurcating reductases that are environmentally widespread.
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Affiliation(s)
- Yaochun Yu
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Fengjun Xu
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Weiyang Zhao
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Calvin Thoma
- Department of Biochemistry, Molecular Biology and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities, MN 55108, USA
| | - Shun Che
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Jack E. Richman
- Department of Biochemistry, Molecular Biology and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities, MN 55108, USA
| | - Bosen Jin
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Yiwen Zhu
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Yue Xing
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
| | - Lawrence Wackett
- Department of Biochemistry, Molecular Biology and Biophysics and Biotechnology Institute, University of Minnesota, Twin Cities, MN 55108, USA
| | - Yujie Men
- Department of Chemical and Environmental Engineering, University of California, Riverside, Riverside, CA 92521, USA
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Bui TH, Zuverza-Mena N, Dimkpa CO, Nason SL, Thomas S, White JC. PFAS remediation in soil: An evaluation of carbon-based materials for contaminant sequestration. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2024; 344:123335. [PMID: 38211874 PMCID: PMC10922530 DOI: 10.1016/j.envpol.2024.123335] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 12/19/2023] [Accepted: 01/08/2024] [Indexed: 01/13/2024]
Abstract
The presence of per- and poly-fluoroalkyl substances (PFAS) in soils is a global concern as these emerging contaminants are highly resistant to degradation and cause adverse effects on human and environmental health at very low concentrations. Sequestering PFAS in soils using carbon-based materials is a low-cost and effective strategy to minimize pollutant bioavailability and exposure, and may offer potential long-term remediation of PFAS in the environment. This paper provides a comprehensive evaluation of current insights on sequestration of PFAS in soil using carbon-based sorbents. Hydrophobic effects originating from fluorinated carbon (C-F) backbone "tail" and electrostatic interactions deriving from functional groups on the molecules' "head" are the two driving forces governing PFAS sorption. Consequently, varying C-F chain lengths and polar functional groups significantly alter PFAS availability and leachability. Furthermore, matrix parameters such as soil organic matter, inorganic minerals, and pH significantly impact PFAS sequestration by sorbent amendments. Materials such as activated carbon, biochar, carbon nanotubes, and their composites are the primary C-based materials used for PFAS adsorption. Importantly, modifying the carbon structural and surface chemistry is essential for increasing the active sorption sites and for strengthening interactions with PFAS. This review evaluates current literature, identifies knowledge gaps in current remediation technologies and addresses future strategies on the sequestration of PFAS in contaminated soil using sustainable novel C-based sorbents.
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Affiliation(s)
- Trung Huu Bui
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA
| | - Nubia Zuverza-Mena
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA
| | - Christian O Dimkpa
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA
| | - Sara L Nason
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA
| | - Sara Thomas
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA
| | - Jason C White
- The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT, 06511, USA.
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Yu Y, Xu F, Zhao W, Thoma C, Che S, Richman JE, Jin B, Zhu Y, Xing Y, Wackett L, Men Y. Electron-bifurcation and fluoride efflux systems in Acetobacterium spp. drive defluorination of perfluorinated unsaturated carboxylic acids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.568471. [PMID: 38168399 PMCID: PMC10760045 DOI: 10.1101/2023.12.13.568471] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
Enzymatic cleavage of C-F bonds in per- and polyfluoroalkyl substances (PFAS) is largely unknown but avidly sought to promote systems biology for PFAS bioremediation. Here, we report the reductive defluorination of α, β-unsaturated per- and polyfluorocarboxylic acids by Acetobacterium spp. Two critical molecular features in Acetobacterium species enabling reductive defluorination are (i) a functional fluoride efflux transporter (CrcB) and (ii) an electron-bifurcating caffeate reduction pathway (CarABCDE). The fluoride transporter was required for detoxification of released fluoride. Car enzymes were implicated in defluorination by the following evidence: (i) only Acetobacterium spp. with car genes catalyzed defluorination; (ii) caffeate and PFAS competed in vivo ; (iii) models from the X-ray structure of the electron-bifurcating reductase (CarC) positioned the PFAS substrate optimally for reductive defluorination; (iv) products identified by 19 F-NMR and high-resolution mass spectrometry were consistent with the model. Defluorination biomarkers identified here were found in wastewater treatment plant metagenomes on six continents.
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