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Farajollahi S, Lombardo NV, Crenshaw MD, Guo HB, Doherty ME, Davison TR, Steel JJ, Almand EA, Varaljay VA, Suei-Hung C, Mirau PA, Berry RJ, Kelley-Loughnane N, Dennis PB. Defluorination of Organofluorine Compounds Using Dehalogenase Enzymes from Delftia acidovorans (D4B). ACS OMEGA 2024; 9:28546-28555. [PMID: 38973860 PMCID: PMC11223199 DOI: 10.1021/acsomega.4c02517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 05/23/2024] [Accepted: 05/28/2024] [Indexed: 07/09/2024]
Abstract
Organofluorine compounds have been widely used as pharmaceuticals, agricultural pesticides, and water-resistant coatings for decades; however, these compounds are recognized as environmental pollutants. The capability of microorganisms and enzymes to defluorinate organofluorine compounds is both rare and highly desirable to facilitate environmental remediation efforts. Recently, a strain of Delftia acidovorans (D4B) was identified with potential biodegradation activity toward perfluoroalkyl substances (PFAS) and other organofluorine compounds. Genomic analysis found haloacid and fluoroacetate dehalogenases as enzymes associated with Delftia acidovorans. Here, defluorination activity of these enzymes toward different fluorinated substrates was investigated after their recombinant expression and purification from E. coli. Using an electrochemical fluoride probe, 19F NMR, and mass spectrometry to monitor defluorination, we identified two dehalogenases, DeHa2 (a haloacid dehalogenase) and DeHa4 (a fluoroacetate dehalogenase), with activity toward mono- and difluoroacetate. Of the two dehalogenases, DeHa4 demonstrated a low pH optimum compared to DeHa2, which lost catalytic activity under acidic conditions. DeHa2 and DeHa4 are relatively small proteins, operate under aerobic conditions, and remain active for days in the presence of substrates. Significantly, while there have been many reports on dehalogenation of monofluoroacetate by dehalogenases, this study adds to the relatively small list of enzymes reported to carry out enzymatic defluorination of the more recalcitrant disubstituted carbon in an organofluorine compound. Thus, DeHa2 and DeHa4 represent organofluorine dehalogenases that may be used in the future to design and engineer robust defluorination agents for environmental remediation efforts.
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Affiliation(s)
- Sanaz Farajollahi
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
| | - Nina V. Lombardo
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
- UES
a BlueHalo Company, 4401
Dayton-Xenia Rd., Dayton, Ohio United States 45432-1894
| | - Michael D. Crenshaw
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
- UES
a BlueHalo Company, 4401
Dayton-Xenia Rd., Dayton, Ohio United States 45432-1894
| | - Hao-Bo Guo
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
- UES
a BlueHalo Company, 4401
Dayton-Xenia Rd., Dayton, Ohio United States 45432-1894
| | - Megan E. Doherty
- Department
of Biology, United States Air Force Academy, Colorado Springs, Colorado United States 80840-5002
| | - Tina R. Davison
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
- UES
a BlueHalo Company, 4401
Dayton-Xenia Rd., Dayton, Ohio United States 45432-1894
| | - Jordan J. Steel
- Department
of Biology, United States Air Force Academy, Colorado Springs, Colorado United States 80840-5002
| | - Erin A. Almand
- Department
of Biology, United States Air Force Academy, Colorado Springs, Colorado United States 80840-5002
| | - Vanessa A. Varaljay
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
- The
Ohio State University, Infectious Diseases
Institute, Columbus, Ohio United States 43210-1132
| | - Chia Suei-Hung
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
| | - Peter A. Mirau
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
| | - Rajiv J. Berry
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
| | - Nancy Kelley-Loughnane
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
| | - Patrick B. Dennis
- Air
Force Research Laboratory, Materials and Manufacturing Directorate, 2179 12th Street, WPAFB, Ohio United States 45433-7131
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Yan M, Gao Z, Xiang X, Wang Q, Song X, Wu Y, Löffler FE, Zeng J, Lin X. Defluorination of monofluorinated alkane by Rhodococcus sp. NJF-7 isolated from soil. AMB Express 2024; 14:65. [PMID: 38842638 PMCID: PMC11156826 DOI: 10.1186/s13568-024-01729-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Accepted: 05/27/2024] [Indexed: 06/07/2024] Open
Abstract
Microbial degradation of fluorinated compounds raised significant attention because of their widespread distribution and potential environmental impacts. Here, we report a bacterial isolate, Rhodococcus sp. NJF-7 capable of defluorinating monofluorinated medium-chain length alkanes. This isolate consumed 2.29 ± 0.13 mmol L- 1 of 1-fluorodecane (FD) during a 52 h incubation period, resulting in a significant release of inorganic fluoride amounting to 2.16 ± 0.03 mmol L- 1. The defluorination process was strongly affected by the initial FD concentration and pH conditions, with lower pH increasing fluoride toxicity to bacterial cells and inhibiting enzymatic defluorination activity. Stoichiometric conversion of FD to fluoride was observed at neutral pH with resting cells, while defluorination was significantly lower at reduced pH (6.5). The discovery of the metabolites decanoic acid and methyl decanoate suggests that the initial attack by monooxygenases may be responsible for the biological defluorination of FD. The findings here provide new insights into microbial defluorination processes, specifically aiding in understanding the environmental fate of organic semi-fluorinated alkane chemicals.
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Affiliation(s)
- Meng Yan
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
| | - Zhaozhao Gao
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
| | - Xingjia Xiang
- Anhui Province Key Laboratory of Wetland Ecosystem Protection and Restoration, School of Resources and Environmental Engineering, Anhui University, Hefei, 230601, China.
| | - Qing Wang
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
| | - Xin Song
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
| | - Yucheng Wu
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
| | - Frank E Löffler
- Department of Civil and Environmental Engineering, Department of Microbiology, Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, TN, 37996, USA
| | - Jun Zeng
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China.
- Department of Biology and Biochemistry, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, People's Republic of China.
| | - Xiangui Lin
- State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Beijing East Road, 71, Nanjing, 210008, China
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3
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Yu Y, Trottmann NF, Schärer MR, Fenner K, Robinson SL. Substrate promiscuity of xenobiotic-transforming hydrolases from stream biofilms impacted by treated wastewater. WATER RESEARCH 2024; 256:121593. [PMID: 38631239 DOI: 10.1016/j.watres.2024.121593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Revised: 04/07/2024] [Accepted: 04/08/2024] [Indexed: 04/19/2024]
Abstract
Organic contaminants enter aquatic ecosystems from various sources, including wastewater treatment plant effluent. Freshwater biofilms play a major role in the removal of organic contaminants from receiving water bodies, but knowledge of the molecular mechanisms driving contaminant biotransformations in complex stream biofilm (periphyton) communities remains limited. Previously, we demonstrated that biofilms in experimental flume systems grown at higher ratios of treated wastewater (WW) to stream water displayed an increased biotransformation potential for a number of organic contaminants. We identified a positive correlation between WW percentage and biofilm biotransformation rates for the widely-used insect repellent, N,N-diethyl-meta-toluamide (DEET) and a number of other wastewater-borne contaminants with hydrolyzable moieties. Here, we conducted deep shotgun sequencing of flume biofilms and identified a positive correlation between WW percentage and metagenomic read abundances of DEET hydrolase (DH) homologs. To test the causality of this association, we constructed a targeted metagenomic library of DH homologs from flume biofilms. We screened our complete metagenomic library for activity with four different substrates, including DEET, and a subset thereof with 183 WW-related organic compounds. The majority of active hydrolases in the metagenomic library preferred aliphatic and aromatic ester substrates while, remarkably, only a single reference enzyme was capable of DEET hydrolysis. Of the 626 total enzyme-substrate combinations tested, approximately 5% were active enzyme-substrate pairs. Metagenomic DH family homologs revealed a broad substrate promiscuity spanning 22 different compounds when summed across all enzymes tested. We biochemically characterized the most promiscuous and active enzymes identified based on metagenomic analysis from uncultivated Rhodospirillaceae and Planctomycetaceae. In addition to characterizing new DH family enzymes, we exemplified a framework for linking metagenome-guided hypothesis generation with experimental validation. Overall, this study expands the scope of known enzymatic contaminant biotransformations for metagenomic hydrolases from WW-receiving stream biofilm communities.
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Affiliation(s)
- Yaochun Yu
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland
| | - Niklas Ferenc Trottmann
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland
| | - Milo R Schärer
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland
| | - Kathrin Fenner
- Department of Environmental Chemistry, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland; Department of Chemistry, University of Zürich, 8057 Zürich, Switzerland
| | - Serina L Robinson
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), 8600 Dübendorf, Switzerland.
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Wu C, Goodrow S, Chen H, Li M. Distinctive biotransformation and biodefluorination of 6:2 versus 5:3 fluorotelomer carboxylic acids by municipal activated sludge. WATER RESEARCH 2024; 254:121431. [PMID: 38471201 DOI: 10.1016/j.watres.2024.121431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 03/04/2024] [Accepted: 03/05/2024] [Indexed: 03/14/2024]
Abstract
Fluorotelomer carboxylic acids (FTCAs) represent an important group of per- and polyfluoroalkyl substances (PFAS) given their high toxicity, bioaccumulation potential, and frequent detection in landfill leachates and PFAS-impacted sites. In this study, we assessed the biodegradability of 6:2 FTCA and 5:3 FTCA by activated sludges from four municipal wastewater treatment plants (WWTPs) in the New York Metropolitan area. Coupling with 6:2 FTCA removal, significant fluoride release (0.56∼1.83 F-/molecule) was evident in sludge treatments during 7 days of incubation. Less-fluorinated transformation products (TPs) were formed, including 6:2 fluorotelomer unsaturated carboxylic acid (6:2 FTUCA), perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), and perfluorobutanoic acid (PFBA). In contrast, little fluoride (0.01∼0.09 F-/molecule) was detected in 5:3 FTCA-dosed microcosms, though 25∼68% of initially dosed 5:3 FTCA was biologically removed. This implies the dominance of "non-fluoride-releasing pathways" that may contribute to the formation of CoA adducts or other conjugates over 5:3 FTCA biotransformation. The discovery of defluorinated 5:3 FTUCA revealed the possibility of microbial attacks of the C-F bond at the γ carbon to initiate the transformation. Microbial community analysis revealed the possible involvement of 9 genera, such as Hyphomicrobium and Dechloromonas, in aerobic FTCA biotransformation. This study unraveled that biotransformation pathways of 6:2 and 5:3 FTCAs can be divergent, resulting in biodefluorination at distinctive degrees. Further research is underscored to uncover the nontarget TPs and investigate the involved biotransformation and biodefluorination mechanisms and molecular basis.
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Affiliation(s)
- Chen Wu
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, United States
| | - Sandra Goodrow
- Division of Science and Research, New Jersey Department of Environmental Protection, Trenton, NJ, United States
| | - Hao Chen
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, United States
| | - Mengyan Li
- Department of Chemistry and Environmental Science, New Jersey Institute of Technology, Newark, NJ, United States.
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5
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Zhang M, Wang W, Gong T, Wu Y, Chen G. Cutting-edge technologies and relevant reaction mechanism difference in treatment of long- and short-chain per- and polyfluoroalkyl substances: A review. CHEMOSPHERE 2024; 354:141692. [PMID: 38490606 DOI: 10.1016/j.chemosphere.2024.141692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/10/2024] [Accepted: 03/11/2024] [Indexed: 03/17/2024]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants. Compared with short-chain PFAS, long-chain PFAS are more hazardous. Currently, little attention has been paid to the differences in reaction mechanisms between long-chain and short-chain PFAS. This pressing concern has prompted studies about eliminating PFAS and revealing the mechanism difference. The reaction rate and reaction mechanism of each technology was focused on, including (1) adsorption, (2) ion exchange (IX), (3) membrane filtration, (4) advanced oxidation, (5) biotransformation, (6) novel functional material, and (7) other technologies (e.g. ecological remediation, hydrothermal treatment (HT), mechanochemical (MC) technology, micro/nanobubbles enhanced technology, and integrated technologies). The greatest reaction rate k of photocatalysis for long- and short-chain PFAS high up to 63.0 h-1 and 19.7 h-1, respectively. However, adsorption, membrane filtration, and novel functional material remediation were found less suitable or need higher operation demand for treating short-chain PFAS. Ecological remediation is more suitable for treating natural waterbody for its environmentally friendly and fair reaction rate. The other technologies all showed good application potential for both short- and long-chain PFAS, and it was more excellent for long-chain PFAS. The long-chain PFAS can be cleavaged into short-chain PFAS by C-chain broken, -CF2 elimination, nucleophilic substitution of F-, and HF elimination. Furthermore, the application of each type of technology was novelly designed; and suggestions for the future development of PFAS remediation technologies were proposed.
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Affiliation(s)
- Meng Zhang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Wenbing Wang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China.
| | - Tiantian Gong
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China
| | - Yulin Wu
- Shanghai Geotechnical Investigations and Design Institute Engineering Consulting (Group) Co. Ltd., China
| | - Guangyao Chen
- School of Material Science and Engineering, Shanghai University, Shanghai, 200444, China
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6
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Xu G, Zhao S, Rogers MJ, Chen C, He J. Global prevalence of organohalide-respiring bacteria dechlorinating polychlorinated biphenyls in sewage sludge. MICROBIOME 2024; 12:54. [PMID: 38491554 PMCID: PMC10943849 DOI: 10.1186/s40168-024-01754-8] [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: 10/27/2023] [Accepted: 01/04/2024] [Indexed: 03/18/2024]
Abstract
BACKGROUND Massive amounts of sewage sludge are generated during biological sewage treatment and are commonly subjected to anaerobic digestion, land application, and landfill disposal. Concurrently, persistent organic pollutants (POPs) are frequently found in sludge treatment and disposal systems, posing significant risks to both human health and wildlife. Metabolically versatile microorganisms originating from sewage sludge are inevitably introduced to sludge treatment and disposal systems, potentially affecting the fate of POPs. However, there is currently a dearth of comprehensive assessments regarding the capability of sewage sludge microbiota from geographically disparate regions to attenuate POPs and the underpinning microbiomes. RESULTS Here we report the global prevalence of organohalide-respiring bacteria (OHRB) known for their capacity to attenuate POPs in sewage sludge, with an occurrence frequency of ~50% in the investigated samples (605 of 1186). Subsequent laboratory tests revealed microbial reductive dechlorination of polychlorinated biphenyls (PCBs), one of the most notorious categories of POPs, in 80 out of 84 sludge microcosms via various pathways. Most chlorines were removed from the para- and meta-positions of PCBs; nevertheless, ortho-dechlorination of PCBs also occurred widely, although to lower extents. Abundances of several well-characterized OHRB genera (Dehalococcoides, Dehalogenimonas, and Dehalobacter) and uncultivated Dehalococcoidia lineages increased during incubation and were positively correlated with PCB dechlorination, suggesting their involvement in dechlorinating PCBs. The previously identified PCB reductive dehalogenase (RDase) genes pcbA4 and pcbA5 tended to coexist in most sludge microcosms, but the low ratios of these RDase genes to OHRB abundance also indicated the existence of currently undescribed RDases in sewage sludge. Microbial community analyses revealed a positive correlation between biodiversity and PCB dechlorination activity although there was an apparent threshold of community co-occurrence network complexity beyond which dechlorination activity decreased. CONCLUSIONS Our findings that sludge microbiota exhibited nearly ubiquitous dechlorination of PCBs indicate widespread and nonnegligible impacts of sludge microbiota on the fate of POPs in sludge treatment and disposal systems. The existence of diverse OHRB also suggests sewage sludge as an alternative source to obtain POP-attenuating consortia and calls for further exploration of OHRB populations in sewage sludge. Video Abstract.
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Affiliation(s)
- Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore, 117576, Singapore
| | - Siyan Zhao
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore, 117576, Singapore
| | - Matthew J Rogers
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore, 117576, Singapore
| | - Chen Chen
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore, 117576, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, Block E2-02-13, 1 Engineering Drive 3, Singapore, 117576, Singapore.
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Zhou T, Li X, Liu H, Dong S, Zhang Z, Wang Z, Li J, Nghiem LD, Khan SJ, Wang Q. Occurrence, fate, and remediation for per-and polyfluoroalkyl substances (PFAS) in sewage sludge: A comprehensive review. JOURNAL OF HAZARDOUS MATERIALS 2024; 466:133637. [PMID: 38306831 DOI: 10.1016/j.jhazmat.2024.133637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 01/19/2024] [Accepted: 01/25/2024] [Indexed: 02/04/2024]
Abstract
Addressing per-and polyfluoroalkyl substances (PFAS) contamination is an urgent environmental concern. While most research has focused on PFAS contamination in water matrices, comparatively little attention has been given to sludge, a significant by-product of wastewater treatment. This critical review presents the latest information on emission sources, global distribution, international regulations, analytical methods, and remediation technologies for PFAS in sludge and biosolids from wastewater treatment plants. PFAS concentrations in sludge matrices are typically in hundreds of ng/g dry weight (dw) in developed countries but are rarely reported in developing and least-developed countries due to the limited analytical capability. In comparison to water samples, efficient extraction and cleaning procedures are crucial for PFAS detection in sludge samples. While regulations on PFAS have mainly focused on soil due to biosolids reuse, only two countries have set limits on PFAS in sludge or biosolids with a maximum of 100 ng/g dw for major PFAS. Biological technologies using microbes and enzymes present in sludge are considered as having high potential for PFAS remediation, as they are eco-friendly, low-cost, and promising. By contrast, physical/chemical methods are either energy-intensive or linked to further challenges with PFAS contamination and disposal. The findings of this review deepen our comprehension of PFAS in sludge and have guided future research recommendations.
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Affiliation(s)
- Ting Zhou
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Xuan Li
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
| | - Huan Liu
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Shiman Dong
- Department of Life Sciences and Systems Biology, University of Torino, Via Accademia Albertina 13, Turin 10123, Italy
| | - Zehao Zhang
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Zhenyao Wang
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Jibin Li
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Long D Nghiem
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia
| | - Stuart J Khan
- School of Civil Engineering, University of Sydney, NSW 2006, Australia
| | - Qilin Wang
- Centre for Technology in Water and Wastewater, School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
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8
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Wei X, Liu P, Bai D, Zhang L, Mao H, Zhang W, Chen T, Yin D, Sun T, Zhang Y, Zhang W. Industrializable and pH-tolerant electropositive imidazolium chloride polymer for high-efficiency removal of perfluoroalkyl carboxylic acids from aqueous solution. JOURNAL OF HAZARDOUS MATERIALS 2024; 465:133095. [PMID: 38056270 DOI: 10.1016/j.jhazmat.2023.133095] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 10/23/2023] [Accepted: 11/23/2023] [Indexed: 12/08/2023]
Abstract
In recent years, various materials have been used to adsorb and remove perfluoroalkyl compounds from water. However, most of these materials have limited applications due to their high cost, complex synthesis, inadequate selectivity and sensitivity, and, even worse, the possibility of introducing secondary pollution. Here, under mild conditions, we prepared an inexpensive imidazolium chloride and nitrogen-rich polymer (TAGX-Cl) with a high cationic loading rate and a high yield (>82%). The adsorbent exhibits excellent pH tolerance (pH=1-9) and achieves nearly 99.9% removal of nine perfluoroalkyl carboxylic acids (PFCAs) within 120 min. Experimental data and theoretical simulations confirmed that synergistic electrostatic interactions, hydrogen bonds, and P-π interactions control the adsorptive ability of TAGX-Cl. This work provides a practical strategy for PFCAs removal.
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Affiliation(s)
- Xiaohui Wei
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Pingping Liu
- Zhengzhou Tobacco Research Institute of CNTC, Fengyang Road, Zhengzhou, Henan 450001, PR China
| | - Danyang Bai
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Luyuan Zhang
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, PR China
| | - Hongyan Mao
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Wenjing Zhang
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Tianqi Chen
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Dan Yin
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, PR China
| | - Tianhua Sun
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China
| | - Yanhao Zhang
- School of Ecology and Environment, Zhengzhou University, Zhengzhou 450001, PR China.
| | - Wenfen Zhang
- College of Chemistry, Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China; Zhengzhou Tobacco Research Institute of CNTC, Fengyang Road, Zhengzhou, Henan 450001, PR China; Food Laboratory of Zhongyuan, Flavour Science Research Center of Zhengzhou University, Kexue Avenue 100, Zhengzhou, Henan 450001, PR China.
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9
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Zhang H, Chen Y, Liu Y, Bowden JA, Townsend TG, Solo-Gabriele HM. Comparison of the PFAS and physical-chemical parameter fluctuations between an ash landfill and a MSW landfill. WASTE MANAGEMENT (NEW YORK, N.Y.) 2024; 174:558-567. [PMID: 38141373 DOI: 10.1016/j.wasman.2023.12.027] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2023] [Revised: 11/16/2023] [Accepted: 12/11/2023] [Indexed: 12/25/2023]
Abstract
Studies of per- and polyfluoroalkyl substances (PFAS) fluctuations at landfills have focused on municipal solid waste (MSW) leachate. Few studies exist that evaluate fluctuations (defined by the coefficient of variation, CV) in MSW incinerator ash (MSWA) landfill leachate and that evaluate PFAS fluctuations in stormwater, groundwater, and treated liquids on-site. In this study, aqueous landfill samples (leachate, treated leachate, stormwater, gas condensate, ambient groundwater, and effluent from a groundwater remediation system) were collected from a MSW and an MSWA landfill geographically located within close proximity (less than 40 km). The objective of this study was to compare the leachate compositions between these two landfill types and to evaluate temporal variations. Results indicated that the CV of total detected PFAS concentrations in leachate was higher for the MSW landfill (CV = 43 %) compared to the MSWA landfill (CV = 16 %). The total detected PFAS concentration in MSW leachate samples (mean: 9641 ng/L) was higher than in MSWA leachate samples (mean: 2621 ng/L) (p < 0.05). Within a landfill, PFAS concentrations were correlated (rs > 0.6, p < 0.05) with alkalinity, total organic carbon (TOC), and ammonia. Results from the on-site leachate treatment system at the MSW landfill indicated reductions in COD, TOC, and ammonia; however, the ∑26PFAS concentration increased 3 % after the treatment. Overall, results demonstrated that differences between landfill types and fluctuations in PFAS within landfills should be considered when designing landfill leachate collection and treatment systems to remove PFAS. The comparative analysis in this study can provide insights into optimizing leachate management for MSW and MSWA landfills.
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Affiliation(s)
- Hekai Zhang
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, FL 33146, United States
| | - Yutao Chen
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, FL 33146, United States
| | - Yalan Liu
- Department of Civil, Environmental and Geomatics Engineering, Florida Atlantic University, Boca Raton, FL, 33431, United States
| | - John A Bowden
- Department of Environmental Engineering Sciences, College of Engineering, University of Florida, Gainesville, FL 32611, United States; Center for Environmental and Human Toxicology & Department of Physiological Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611, United States
| | - Timothy G Townsend
- Department of Environmental Engineering Sciences, College of Engineering, University of Florida, Gainesville, FL 32611, United States
| | - Helena M Solo-Gabriele
- Department of Civil, Architectural, and Environmental Engineering, College of Engineering, University of Miami, Coral Gables, FL 33146, United States.
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10
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Fang B, Zhang Y, Chen H, Qiao B, Yu H, Zhao M, Gao M, Li X, Yao Y, Zhu L, Sun H. Stability and Biotransformation of 6:2 Fluorotelomer Sulfonic Acid, Sulfonamide Amine Oxide, and Sulfonamide Alkylbetaine in Aerobic Sludge. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:2446-2457. [PMID: 38178542 DOI: 10.1021/acs.est.3c05506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2024]
Abstract
The 6:2 fluorotelomer sulfonamide (6:2 FTSAm)-based compounds signify a prominent group of per- and polyfluoroalkyl substances (PFAS) widely used in contemporary aqueous film-forming foam (AFFF) formulations. Despite their widespread presence, the biotransformation behavior of these compounds in wastewater treatment plants remains uncertain. This study investigated the biotransformation of 6:2 FTSAm-based amine oxide (6:2 FTNO), alkylbetaine (6:2 FTAB), and 6:2 fluorotelomer sulfonic acid (6:2 FTSA) in aerobic sludge over a 100-day incubation period. The biotransformation of 6:2 fluorotelomer sulfonamide alkylamine (6:2 FTAA), a primary intermediate product of 6:2 FTNO, was indirectly assessed. Their stability was ranked based on the estimated half-lives (t1/2): 6:2 FTAB (no obvious products were detected) ≫ 6:2 FTSA (t1/2 ≈28.8 days) > 6:2 FTAA (t1/2 ≈11.5 days) > 6:2 FTNO (t1/2 ≈1.2 days). Seven transformation products of 6:2 FTSA and 15 products of 6:2 FTNO were identified through nontarget and suspect screening using high-resolution mass spectrometry. The transformation pathways of 6:2 FTNO and 6:2 FTSA in aerobic sludge were proposed. Interestingly, 6:2 FTSAm was hardly hydrolyzed to 6:2 FTSA and further biotransformed to perfluoroalkyl carboxylic acids (PFCAs). Furthermore, the novel pathways for the generation of perfluoroheptanoic acid (PFHpA) from 6:2 FTSA were revealed.
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Affiliation(s)
- Bo Fang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yaozhi Zhang
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Hao Chen
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Biting Qiao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Hao Yu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Maosen Zhao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Meng Gao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Xiaoxiao Li
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Yiming Yao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Lingyan Zhu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
| | - Hongwen Sun
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China
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11
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Zhu X, Yu Y, Meng W, Huang J, Su G, Zhong Y, Yu X, Sun J, Jin L, Peng P, Zhu L. Aerobic Microbial Transformation of Fluorinated Liquid Crystal Monomer: New Pathways and Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:510-521. [PMID: 38100654 DOI: 10.1021/acs.est.3c04256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2023]
Abstract
Fluorinated liquid crystal monomers (FLCMs) have been suggested as emerging contaminants, raising global concern due to their frequent occurrence, potential toxic effects, and endurance capacity in the environment. However, the environmental fate of the FLCMs remains unknown. To fill this knowledge gap, we investigated the aerobic microbial transformation mechanisms of an important FLCM, 4-[difluoro(3,4,5-trifluorophenoxy)methyl]-3, 5-difluoro-4'-propylbiphenyl (DTMDPB), using an enrichment culture termed as BG1. Our findings revealed that 67.5 ± 2.1% of the initially added DTMDPB was transformed in 10 days under optimal conditions. A total of 14 microbial transformation products obtained due to a series of reactions (e.g., reductive defluorination, ether bond cleavage, demethylation, oxidative hydroxylation and aromatic ring opening, sulfonation, glucuronidation, O-methylation, and thiolation) were identified. Consortium BG1 harbored essential genes that could transform DTMDPB, such as dehalogenation-related genes [e.g., glutathione S-transferase gene (GST), 2-haloacid dehalogenase gene (2-HAD), nrdB, nuoC, and nuoD]; hydroxylating-related genes hcaC, ubiH, and COQ7; aromatic ring opening-related genes ligB and catE; and methyltransferase genes ubiE and ubiG. Two DTMDPB-degrading strains were isolated, which are affiliated with the genus Sphingopyxis and Agromyces. This study provides a novel insight into the microbial transformation of FLCMs. The findings of this study have important implications for the development of bioremediation strategies aimed at addressing sites contaminated with FLCMs.
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Affiliation(s)
- Xifen Zhu
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China
| | - Yuanyuan Yu
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China
| | - Weikun Meng
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China
| | - Jiahui Huang
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China
| | - Guanyong Su
- Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse, School of Environmental and Biological Engineering, Nanjing University of Science and Technology, Nanjing 210094, PR China
| | - Yin Zhong
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China
| | - Xiaolong Yu
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China
| | - Jianteng Sun
- Guangdong Provincial Key Laboratory of Petrochemical Pollution Processes and Control, School of Environmental Science and Engineering, Guangdong University of Petrochemical Technology, Maoming, Guangdong 525000, China
| | - Ling Jin
- Department of Civil and Environmental Engineering and Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Hung Hom, Kowloon 999077, Hong Kong
| | - Ping'an Peng
- State Key Laboratory of Organic Geochemistry, Guangdong Provincial Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, China
| | - Lizhong Zhu
- Department of Environmental Science, Zhejiang University, Hangzhou, Zhejiang 310058, China
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12
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Folkerson AP, Mabury SA. A Comparative Biodegradation Study to Assess the Ultimate Fate of Novel Highly Functionalized Hydrofluoroether Alcohols in Wastewater Treatment Plant Microcosms and Surface Waters. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2023. [PMID: 38131503 DOI: 10.1002/etc.5815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 09/05/2023] [Accepted: 12/20/2023] [Indexed: 12/23/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are a class of chemicals present in a wide range of commercial and consumer products due to their water-repellency, nonstick, or surfactant properties, resulting from their chemical and thermal stability. This stability, however, often leads to persistence in the environment when they are inevitability released. We utilized microbial microcosms from wastewater treatment plant (WWTP) sludge to determine how employing different functional groups such as heteroatom linkages, varying chain lengths, and hydrofluoroethers (HFEs) will impact the ultimate fate of these novel PFAS structures. A suite of five novel fluorosurfactant building blocks (F7 C3 OCHFCF2 SCH2 CH2 OH (FESOH), F3 COCHFCF2 SCH2 CH2 OH (MeFESOH), F7 C3 OCHFCF2 OCH2 CH2 OH (ProFdiEOH), F7 C3 OCHFCF2 CH2 OH (ProFEOH), and F3 COCHFCF2 OCH2 CH2 OH (MeFdiEOH)) and their select transformation products, were incubated in WWTP aerobic microcosms to determine structure-activity relationships. The HFE alcohol congeners with a thioether (FESOH and MeFESOH) were observed to transform faster than the ether congeners, while also producing second-generation HFE acid products (F7 C3 OCHFC(O)OH (2H-3:2 polyfluoroalkyl ether carboxylic acid [PFECA]) and F3 COCHFC(O)OH (2H-1:2 PFECA). Subsequent biodegradation experiments with 2H-1:2 PFESA and 2H-1:2 PFECA displayed no further transformation over 74 days. Surface water Photofate experiments compared 2H-1:2 PFECA, and 2H-1:2 polyfluorinated ether sulfonate (PFESA) with their fully fluorinated ether acid counterparts, and demonstrated the potential for both HFE acid species to completely mineralize over extended periods of time, a fate that highlights the value of studying novel PFAS functionalization. Environ Toxicol Chem 2024;00:1-9. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Andrew P Folkerson
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
| | - Scott A Mabury
- Department of Chemistry, University of Toronto, Toronto, Ontario, Canada
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13
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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: 0] [Impact Index Per Article: 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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14
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Marciesky M, Aga DS, Bradley IM, Aich N, Ng C. Mechanisms and Opportunities for Rational In Silico Design of Enzymes to Degrade Per- and Polyfluoroalkyl Substances (PFAS). J Chem Inf Model 2023; 63:7299-7319. [PMID: 37981739 PMCID: PMC10716909 DOI: 10.1021/acs.jcim.3c01303] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 11/21/2023]
Abstract
Per and polyfluoroalkyl substances (PFAS) present a unique challenge to remediation techniques because their strong carbon-fluorine bonds make them difficult to degrade. This review explores the use of in silico enzymatic design as a potential PFAS degradation technique. The scope of the enzymes included is based on currently known PFAS degradation techniques, including chemical redox systems that have been studied for perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) defluorination, such as those that incorporate hydrated electrons, sulfate, peroxide, and metal catalysts. Bioremediation techniques are also discussed, namely the laccase and horseradish peroxidase systems. The redox potential of known reactants and enzymatic radicals/metal-complexes are then considered and compared to potential enzymes for degrading PFAS. The molecular structure and reaction cycle of prospective enzymes are explored. Current knowledge and techniques of enzyme design, particularly radical-generating enzymes, and application are also discussed. Finally, potential routes for bioengineering enzymes to enable or enhance PFAS remediation are considered as well as the future outlook for computational exploration of enzymatic in situ bioremediation routes for these highly persistent and globally distributed contaminants.
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Affiliation(s)
- Melissa Marciesky
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
| | - Diana S Aga
- Department of Chemistry, State University of New York at Buffalo, Buffalo, New York 14260, United States
| | - Ian M Bradley
- Department of Civil, Structural, and Environmental Engineering, State University of New York at Buffalo, Buffalo, New York 14228, United States
- Research and Education in Energy, Environmental and Water (RENEW) Institute, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States
| | - Nirupam Aich
- Department of Civil and Environmental Engineering, University of Nebraska─Lincoln, Lincoln, Nebraska 68588-0531, United States
| | - Carla Ng
- Department of Chemical and Petroleum Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, United States
- Department of Civil and Environmental Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, United States
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15
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Mothersole R, Wynne FT, Rota G, Mothersole MK, Liu J, Van Hamme JD. Formation of CoA Adducts of Short-Chain Fluorinated Carboxylates Catalyzed by Acyl-CoA Synthetase from Gordonia sp. Strain NB4-1Y. ACS OMEGA 2023; 8:39437-39446. [PMID: 37901528 PMCID: PMC10601079 DOI: 10.1021/acsomega.3c05147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 09/20/2023] [Indexed: 10/31/2023]
Abstract
Perfluoroalkyl and polyfluoroalkyl substances (PFAS) make up a group of anthropogenic chemicals with a myriad of applications. However, some PFAS have been shown to negatively impact human health and the environment, leading to increased regulation, with some countries making efforts to phase out their use. PFAS fate in the environment is driven by physical, chemical, and biological processes, with microbial communities in matrices such as soil and sewage sludge being known to generate a range of low-molecular-weight PFAS metabolites. Proposed metabolic intermediates for both mixed and pure microbial cultures include fluorinated carboxylates that may be activated by CoA prior to β-oxidation and defluorination, although thus far, no PFAS-CoA adducts have been reported. Herein, we expressed and purified acyl-CoA synthetase (ACS) from the soil bacterium Gordonia sp. strain NB4-1Y and performed an analysis of substrate scope and enzyme kinetics using fluorinated and nonfluorinated carboxylates. We determined that ACS was able to catalyze the formation of CoA adducts of 3,3,3-trifluoropropionic acid, 5,5,5-trifluoropentanoic acid, 4,5,5-trifluoropent-4-enoic acid, and 4,4,5,5,5-pentafluoropentanoic acid. Kinetic analysis revealed a 90-98% decrease in kcat between nonfluorinated carboxylates and their fluorinated analogues. This provides evidence to validate proposed enzymatic pathways for microbial PFAS metabolism that proceed via an activation step involving the formation of CoA adducts.
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Affiliation(s)
- Robert
G. Mothersole
- Department
of Biological Sciences, Thompson Rivers
University, 805 TRU Way, Kamloops, BC V2C 0C8, Canada
| | - Foster T. Wynne
- Department
of Biological Sciences, Thompson Rivers
University, 805 TRU Way, Kamloops, BC V2C 0C8, Canada
| | - Gaia Rota
- Department
of Biological Sciences, Thompson Rivers
University, 805 TRU Way, Kamloops, BC V2C 0C8, Canada
| | - Mina K. Mothersole
- Department
of Biological Sciences, Thompson Rivers
University, 805 TRU Way, Kamloops, BC V2C 0C8, Canada
| | - Jinxia Liu
- Department
of Civil Engineering, McGill University, 817 Sherbrooke Street West, Montreal, QC H3A
0C3, Canada
| | - Jonathan D. Van Hamme
- Department
of Biological Sciences, Thompson Rivers
University, 805 TRU Way, Kamloops, BC V2C 0C8, Canada
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16
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Jin B, Zhu Y, Zhao W, Liu Z, Che S, Chen K, Lin YH, Liu J, Men Y. Aerobic Biotransformation and Defluorination of Fluoroalkylether Substances (ether PFAS): Substrate Specificity, Pathways, and Applications. ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS 2023; 10:755-761. [PMID: 37719205 PMCID: PMC10501197 DOI: 10.1021/acs.estlett.3c00411] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/19/2023] [Revised: 07/27/2023] [Accepted: 07/31/2023] [Indexed: 09/19/2023]
Abstract
Fluoroalkylether substances (ether PFAS) constitute a large group of emerging PFAS with uncertain environmental fate. Among them, GenX is the well-known alternative to perfluorooctanoic acid and one of the six proposed PFAS to be regulated by the U.S. Environmental Protection Agency. This study investigated the structure-biodegradability relationship for 12 different ether PFAS with a carboxylic acid headgroup in activated sludge communities. Only polyfluorinated ethers with at least one -CH2- moiety adjacent to or a C=C bond in the proximity of the ether bond underwent active biotransformation via oxidative and hydrolytic O-dealkylation. The bioreactions at ether bonds led to the formation of unstable fluoroalcohol intermediates subject to spontaneous defluorination. We further demonstrated that this aerobic biotransformation/defluorination could complement the advanced reduction process in a treatment train system to achieve more cost-effective treatment for GenX and other recalcitrant perfluorinated ether PFAS. These findings provide essential insights into the environmental fate of ether PFAS, the design of biodegradable alternative PFAS, and the development of cost-effective ether PFAS treatment strategies.
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Affiliation(s)
- Bosen Jin
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yiwen Zhu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Weiyang Zhao
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Zekun Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Shun Che
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Kunpeng Chen
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Ying-Hsuan Lin
- Department
of Environmental Sciences, University of
California, Riverside, California 92521, United States
| | - Jinyong Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
| | - Yujie Men
- Department
of Chemical and Environmental Engineering, University of California, Riverside, California 92521, United States
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17
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Sorn S, Hara-Yamamura H, Vet S, Xiao M, Hoek EMV, Honda R. Biological treatment of perfluorooctanesulfonic acid (PFOS) using microbial capsules of a polysulfone membrane. CHEMOSPHERE 2023; 329:138585. [PMID: 37028728 DOI: 10.1016/j.chemosphere.2023.138585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 03/30/2023] [Accepted: 04/01/2023] [Indexed: 05/03/2023]
Abstract
Perfluorooctanesulfonic acid (PFOS) is a persistent organic substance that has been extensively applied in many industries and causes severe, widespread adverse health impacts on humans and the environment. The development of an effective PFOS treatment method with affordable operational costs has been expected. This study proposes the biological treatment of PFOS using microbial capsules enclosing a PFOS-reducing microbial consortium. The objective of this study was to evaluate the performance of the polymeric membrane encapsulation technique for the biological removal of PFOS. First, a PFOS-reducing bacterial consortium, composed of Paracoccus (72%), Hyphomicrobium (24%), and Micromonosporaceae (4%), was enriched from activated sludge by acclimation and subsequent subculturing with PFOS containing media. The bacterial consortium was first immobilized in alginate gel beads, then enclosed in membrane capsules by coating the gel beads with a 5% or 10% polysulfone (PSf) membrane. The introduction of microbial membrane capsules could increase PFOS reduction to between 52% and 74% compared with free cell suspension, which reduced by 14% over three weeks. Microbial capsules coated with 10% PSf membrane demonstrated the highest PFOS reduction at 80% and physical stability for six weeks. Candidate metabolites including perfluorobutanoic acid (PFBA) and 3,3,3- trifluoropropionic acid were detected by FTMS, suggesting the possible biological degradation of PFOS. In microbial membrane capsules, the initial adsorption of PFOS on the shell membrane layer enhanced subsequent biosorption and biological degradation by PFOS-reducing bacteria immobilized in the core alginate gel beads. The 10%-PSf microbial capsules exhibited a thicker membrane layer with the fabric structure of a polymer network, which maintained longer physical stability than 5%-PSf microbial capsules. This outcome suggests the potential application of microbial membrane capsules to PFOS-contaminated water treatment.
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Affiliation(s)
- Sovannlaksmy Sorn
- Graduate School of Natural Science and Technology, Kanazawa University, Japan
| | | | - Sreyla Vet
- Graduate School of Natural Science and Technology, Kanazawa University, Japan
| | - Minhao Xiao
- Department of Civil and Environmental Engineering, University of California, Los Angeles, USA
| | - Eric M V Hoek
- Department of Civil and Environmental Engineering, University of California, Los Angeles, USA
| | - Ryo Honda
- Faculty of Geosciences and Civil Engineering, Kanazawa University, Japan; Department of Civil and Environmental Engineering, University of California, Los Angeles, USA.
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18
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Tsuda N, Honda Y, Schaefer E, Lian P, Muneer A, Blake TJ, Hammad LA. The environmental degradability of DEMNUM, a typical PFPE polymer. CHEMOSPHERE 2023:139331. [PMID: 37379990 DOI: 10.1016/j.chemosphere.2023.139331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 06/22/2023] [Accepted: 06/23/2023] [Indexed: 06/30/2023]
Abstract
The three environmental degradation tests of hydrolysis, indirect photolysis and Zahn-Wellens microbial degradation were conducted according to the OECD and the US EPA guidelines on DEMNUM, a typical linear perfluoropolyether polymer. Low mass degradation products that formed in each test were structurally characterized and indirectly quantified by liquid chromatography mass spectrometry (LC/MS) using a reference compound and an internal standard of similar structure. The degradation of the polymer was assumed to directly correlate with the appearance of lower mass species. The hydrolysis experiment at 50 °C showed the appearance of less than a dozen low mass species with increasing pH but at the negligible total estimated amount of ∼2 ppm relative to polymer. A dozen low mass perfluoro acid entities also appeared following the indirect photolysis experiment in synthetic humic water. Their maximum total amount was at ∼150 ppm relative to polymer. The largest amount of low mass species formed during the Zahn-Wellens biodegradation test amounted to only ∼80 ppm relative to polymer. The Zahn-Wellens conditions tended to produce larger low mass molecules than the ones formed under photolysis. The results from all three tests indicate that the polymer is stable and non-degradable in the environment.
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Affiliation(s)
- Nobuhiko Tsuda
- Daikin Industries, Ltd., 1-1 Nishi-Hitotsuya, Settsu-shi, Osaka, 566-8585, Japan.
| | - Yoshitaka Honda
- Daikin Industries, Ltd., 1-1 Nishi-Hitotsuya, Settsu-shi, Osaka, 566-8585, Japan
| | - Edward Schaefer
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Peizhi Lian
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Asmaa Muneer
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Timothy J Blake
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
| | - Loubna A Hammad
- Eurofins EAG Agroscience, LLC, 8598 Commerce Drive, Easton, MD, 21601, USA
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19
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Kumar R, Dada TK, Whelan A, Cannon P, Sheehan M, Reeves L, Antunes E. Microbial and thermal treatment techniques for degradation of PFAS in biosolids: A focus on degradation mechanisms and pathways. JOURNAL OF HAZARDOUS MATERIALS 2023; 452:131212. [PMID: 36934630 DOI: 10.1016/j.jhazmat.2023.131212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 03/09/2023] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent organic chemicals detected in biosolids worldwide, which have become a significant concern for biosolids applications due to their increasing environmental risks. Hence, it is pivotal to understand the magnitude of PFAS contamination in biosolids and implement effective technologies to reduce their contamination and prevent hazardous aftermaths. Thermal techniques such as pyrolysis, incineration and gasification, and biodegradation have been regarded as impactful solutions to degrade PFAS and transform biosolids into value-added products like biochar. These techniques can mineralize PFAS compounds under specific operating parameters, which can lead to unique degradation mechanisms and pathways. Understanding PFAS degradation mechanisms can pave the way to design the technology and to optimize the process conditions. Therefore, in this review, we aim to review and compare PFAS degradation mechanisms in thermal treatment like pyrolysis, incineration, gasification, smouldering combustion, hydrothermal liquefaction (HTL), and biodegradation. For instance, in biodegradation of perfluorooctane sulfonic acid (PFOS), firstly C-S bond cleavage occurs which is followed by hydroxylation, decarboxylation and defluorination reactions to form perfluoroheptanoic acid. In HTL, PFOS degradation is carried through OH-catalyzed series of nucleophilic substitution and decarboxylation reactions. In contrast, thermal PFOS degradation involves a three-step random-chain scission pathway. The first step includes C-S bond cleavage, followed by defluorination of perfluoroalkyl radical, and radical chain propagation reactions. Finally, the termination of chain propagation reactions produces very short-fluorinated units. We also highlighted important policies and strategies employed worldwide to curb PFAS contamination in biosolids.
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Affiliation(s)
- Ravinder Kumar
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Tewodros Kassa Dada
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Anna Whelan
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia; Townsville City Council, Wastewater Operations, Townsville, QLD 4810, Australia
| | | | - Madoc Sheehan
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia
| | - Louise Reeves
- Queensland Water Directorate, Brisbane, QLD 4009, Australia
| | - Elsa Antunes
- College of Science & Engineering, James Cook University, Townsville, QLD 4811, Australia.
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20
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Hnatko JP, Liu C, Elsey JL, Dong S, Fortner JD, Pennell KD, Abriola LM, Cápiro NL. Microbial Reductive Dechlorination by a Commercially Available Dechlorinating Consortium Is Not Inhibited by Perfluoroalkyl Acids (PFAAs) at Field-Relevant Concentrations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023. [PMID: 37216485 DOI: 10.1021/acs.est.2c04815] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Perfluoroalkyl acids (PFAAs) have been shown to inhibit biodegradation (i.e., organohalide respiration) of chlorinated ethenes. The potential negative impacts of PFAAs on microbial species performing organohalide respiration, particularly Dehalococcoides mccartyi (Dhc), and the efficacy of in situ bioremediation are a critical concern for comingled PFAA-chlorinated ethene plumes. Batch reactor (no soil) and microcosm (with soil) experiments, containing a PFAA mixture and bioaugmented with KB-1, were completed to assess the impact of PFAAs on chlorinated ethene organohalide respiration. In batch reactors, PFAAs delayed complete biodegradation of cis-1,2-dichloroethene (cis-DCE) to ethene. Maximum substrate utilization rates (a metric for quantifying biodegradation rates) were fit to batch reactor experiments using a numerical model that accounted for chlorinated ethene losses to septa. Fitted values for cis-DCE and vinyl chloride biodegradation were significantly lower (p < 0.05) in batch reactors containing ≥50 mg/L PFAAs. Examination of reductive dehalogenase genes implicated in ethene formation revealed a PFAA-associated change in the Dhc community from cells harboring the vcrA gene to those harboring the bvcA gene. Organohalide respiration of chlorinated ethenes was not impaired in microcosm experiments with PFAA concentrations of 38.7 mg/L and less, suggesting that a microbial community containing multiple strains of Dhc is unlikely to be inhibited by PFAAs at lower, environmentally relevant concentrations.
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Affiliation(s)
- Jason P Hnatko
- Environmental Resources Management (ERM), Boston, Massachusetts 02108, United States
| | - Chen Liu
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Jack L Elsey
- Department of Civil and Environmental Engineering, Tufts University, Medford, Massachusetts 02155, United States
| | - Sheng Dong
- Department of Civil and Environmental Engineering, Auburn University, Auburn, Alabama 36849, United States
| | - John D Fortner
- Department of Chemical and Environmental Engineering, Yale University, New Haven, Connecticut 06520, United States
| | - Kurt D Pennell
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Linda M Abriola
- School of Engineering, Brown University, Providence, Rhode Island 02912, United States
| | - Natalie L Cápiro
- Department of Biological and Environmental Engineering, Cornell University, Ithaca, New York 14853, United States
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21
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Jin B, Liu H, Che S, Gao J, Yu Y, Liu J, Men Y. Substantial defluorination of polychlorofluorocarboxylic acids triggered by anaerobic microbial hydrolytic dechlorination. NATURE WATER 2023; 1:451-461. [PMID: 38405335 PMCID: PMC10888525 DOI: 10.1038/s44221-023-00077-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2022] [Accepted: 04/04/2023] [Indexed: 02/27/2024]
Abstract
Chlorinated polyfluorocarboxylic acids (Cl-PFCAs) derived from the widely used chlorotrifluoroethylene (CTFE) polymers and oligomers may enter and influence the aquatic environment. Here, we report significant defluorination of Cl-PFCAs by an anaerobic microbial community via novel pathways triggered by anaerobic microbial dechlorination. Cl-PFCAs first underwent microbial reductive, hydrolytic, and eliminative dechlorination, and it was the hydrolytic dechlorination that led to significant spontaneous defluorination. Hydrolytic dechlorination was favored with increased Cl-substitutions. An isolated, highly enriched anaerobic defluorinating culture was dominated by two genomes closest to Desulfovibrio aminophilus and Sporomusa sphaeroides, both of which exhibited active defluorination of CTFE tetramer acid. It implies the critical role played by anaerobic non-respiratory hydrolytic dechlorination in the fate of chlorinated polyfluoro-chemicals in natural and engineered water environments. The greatly enhanced biodegradability by Cl-substitutions also sheds light on the design of cost-effective treatment biotechnologies, as well as alternative PFAS that are readily biodegradable and less toxic.
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Affiliation(s)
- Bosen Jin
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Huaqing Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Shun Che
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
| | - Jinyu Gao
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Yaochun Yu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
| | - Jinyong Liu
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
| | - Yujie Men
- Department of Chemical and Environmental Engineering, University of California, Riverside, California, 92521, United States
- Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, United States
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22
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Sima MW, Huang S, Jaffé PR. Modeling the kinetics of perfluorooctanoic and perfluorooctane sulfonic acid biodegradation by Acidimicrobium sp. Strain A6 during the feammox process. JOURNAL OF HAZARDOUS MATERIALS 2023; 448:130903. [PMID: 36764250 DOI: 10.1016/j.jhazmat.2023.130903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Revised: 09/20/2022] [Accepted: 01/27/2023] [Indexed: 06/18/2023]
Abstract
Per- and polyfluoroalkyl substances (PFAS) are emerging contaminants of concern due to their health effects and persistence in the environment. Although perfluoroalkyl acids (PFAAs), such as perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) are very difficult to biodegrade because they are completely saturated with fluorine, it has recently been shown that Acidimicrobium sp. A6 (A6), which oxidizes ammonium under iron reducing conditions (Feammox process), can defluorinate PFAAs. A kinetic model was developed and tested in this study using results from previously published laboratory experiments, augmented with results from additional incubations, to couple the Feammox process to PFAS defluorination. The experimental results show higher Feammox activity and PFAS degradation in the A6 enrichment cultures than in the highly enriched A6 cultures. The coupled experimental and modeling results show that the PFAS defluorination rate is proportional to the rate of ammonium oxidation. The ammonium oxidation rate and the defluorination rate increase monotonically, but not linearly, with increasing A6 biomass. Given that different experiments had different level of Feammox activity, the parameters required to simulate the Feammox varied between A6 cultures. Nonetheless, the kinetic model was able to simulate an anaerobic incubation system and show that PFAS defluorination is proportional to the Feammox activity.
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Affiliation(s)
- Matthew W Sima
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Shan Huang
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA
| | - Peter R Jaffé
- Department of Civil and Environmental Engineering, Princeton University, Princeton, NJ 08544, USA.
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23
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Xiao J, Huang J, Wang Y, Qian X. The fate and behavior of perfluorooctanoic acid (PFOA) in constructed wetlands: Insights into potential removal and transformation pathway. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 861:160309. [PMID: 36403847 DOI: 10.1016/j.scitotenv.2022.160309] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2022] [Revised: 11/10/2022] [Accepted: 11/15/2022] [Indexed: 06/16/2023]
Abstract
Although constructed wetland (CW) technology is widely used to eliminate emerging organic pollutants, the removal pathway of perfluoroalkyl and polyfluoroalkyl substances (PFASs) in CW system have not been fully understood yet. This study aims to deeply probe into the fate and behavior of perfluorooctanoic acid (PFOA) in CW system. Findings indicated that the removal efficiency of PFOA by CW system was 49.69-73.63 % with initial concentrations at 100-1000 μg/L. Substrate was the main "sink" of PFOA into the CWs (46.22-50.83 %), and the plant uptake (1.99-2.48 %) accounted for a small proportion. Transformation products in the effluent of CW systems included a series of short-chain perfluorinated carboxylic acids (PFCAs), hydrogen-containing perfluoroalkanes and other organic fluorides. Activated pathways of xenobiotics biodegradation suggested that enzyme-mediated biochemical reactions might be responsible for the PFOA transformation. The transformation pathway included enzymatic decarboxylation, hydroxylation, hydrolysis, dehydrogenation and dehalogenation, as well as non-enzymatic reactions. These discoveries provide new insights into the in-depth understanding environmental behavior of PFOA in ecosystem and lay the foundation for further ecological remediation.
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Affiliation(s)
- Jun Xiao
- School of Civil Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Juan Huang
- School of Civil Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China.
| | - Ying Wang
- School of Civil Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
| | - Xiuwen Qian
- School of Civil Engineering, Southeast University, Nanjing, Jiangsu 211189, PR China
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24
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Berhanu A, Mutanda I, Taolin J, Qaria MA, Yang B, Zhu D. A review of microbial degradation of per- and polyfluoroalkyl substances (PFAS): Biotransformation routes and enzymes. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 859:160010. [PMID: 36356780 DOI: 10.1016/j.scitotenv.2022.160010] [Citation(s) in RCA: 27] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2022] [Revised: 10/26/2022] [Accepted: 11/03/2022] [Indexed: 06/16/2023]
Abstract
Since the 1950s, copious amounts of per- and polyfluoroalkyl substances (PFAS) (dubbed "forever chemicals") have been dumped into the environment, causing heavy contamination of soil, surface water, and groundwater sources. Humans, animals, and the environment are frequently exposed to PFAS through food, water, consumer products, as well as waste streams from PFAS-manufacturing industries. PFAS are a large group of synthetic organic fluorinated compounds with widely diverse chemical structures that are extremely resistant to microbial degradation. Their persistence, toxicity to life on earth, bioaccumulation tendencies, and adverse health and ecological effects have earned them a "top priority pollutant" designation by regulatory bodies. Despite that a number of physicochemical methods exist for PFAS treatment, they suffer from major drawbacks regarding high costs, use of high energy and incomplete mineralization (destruction of the CF bond). Consequently, microbial degradation and enzymatic treatment of PFAS are highly sought after as they offer a complete, cheaper, sustainable, and environmentally friendly alternative. In this critical review, we provide an overview of the classification, properties, and interaction of PFAS within the environment relevant to microbial degradation. We discuss latest developments in the biodegradation of PFAS by microbes, transformation routes, transformation products and degradative enzymes. Finally, we highlight the existing challenges, limitations, and prospects of bioremediation approaches in treating PFAS and proffer possible solutions and future research directions.
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Affiliation(s)
- Ashenafi Berhanu
- Biofuels Institute, School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China; Haramaya Institute of Technology, Department of Chemical Engineering, Haramaya University, Dire Dawa, Ethiopia
| | - Ishmael Mutanda
- Biofuels Institute, School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ji Taolin
- Biofuels Institute, School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Majjid A Qaria
- Biofuels Institute, School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Bin Yang
- Bioproducts, Sciences and Engineering Laboratory, Department of Biological Systems Engineering, Washington State University, Richland, WA 99354, USA
| | - Daochen Zhu
- Biofuels Institute, School of Environmental and Safety Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China.
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25
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Khan MF, Murphy CD. Fluorotelomer alcohols are efficiently biotransformed by Cunninghamella elegans. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:23613-23623. [PMID: 36327087 DOI: 10.1007/s11356-022-23901-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
Cunninghamella elegans is a well-studied fungus that biotransforms a range of xenobiotics owing to impressive cytochrome P450 (CYP) activity. In this paper, we report the biotransformation of 6:2 fluorotelomer alcohol (6:2 FTOH) by the fungus, yielding a range of fluorinated products that were detectable by fluorine-19 nuclear magnetic resonance spectroscopy (19F NMR), gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). Upon incubation with the pre-grown cultures, the substrate (100 mg/L) was completely consumed within 48 h, which is faster biotransformation than other fungi that have hitherto been studied. The main metabolite formed was the 5:3 fluorotelomer carboxylic acid (5:3 FTCA), which accumulated in the culture supernatant. When the cytochrome P450 inhibitor 1-aminobenzotriazole was included in the culture flasks, there was no biotransformation of 6:2 FTOH, indicating that these enzymes are key to the catalysis. Furthermore, when exogenous 5:3 FTCA was added to the fungus, the standard biotransformation of the drug flurbiprofen was inhibited, strongly suggesting that the main fluorotelomer alcohol biotransformation product inhibits CYP activity and accounts for its accumulation.
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Affiliation(s)
- Mohd Faheem Khan
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Cormac D Murphy
- UCD School of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin 4, Ireland.
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26
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Chi N, Liu J, Lei M, Feng L. Preparation of amphiphilic cationic polyacrylamide (CPAM) with cationic microblock structure to enhance printing and dyeing sludge dewatering and condition performance. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:13079-13093. [PMID: 36125686 DOI: 10.1007/s11356-022-23067-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Accepted: 09/13/2022] [Indexed: 06/15/2023]
Abstract
Flocculation is an important pretreatment technology for sludge dewatering, and the flocculant's performance is the key factor to determine the flocculation effect. Cationic polyacrylamide (CPAM) is commonly used in dewatering and conditioning of printing and dyeing sludge (PD sludge), and the research of high-efficiency flocculant is a hot spot in the field of PD sludge dewatering. Hydrophobic butylacrylate (BA) and (2-(Methacryloyloxy)ethyl) trimethylammonium chloride (DMC) were introduced into the copolymer, and amphiphilic (hydrophilic/lipophilic) CPAM, namely TP-ADB, with microblock structure was synthesized by ultrasonic initiated template copolymerization in this study. The functional group composition of TP-ADB was determined by FTIR and 1H NMR. Thermogravimetric analysis (TGA) showed that TP-ADB had good thermal stability. The amphiphilic rheological properties of the copolymer were measured according to the apparent viscosity. In addition, 1H NMR and TGA results confirmed the existence of microblock structure in the copolymer chain. The polymerization mechanism was discussed by association coefficient (KM) measurement. The results showed that the template copolymerization initiated by ultrasonic followed the law of free radical copolymerization. The pre-adsorption of DMC with sodium polyacrylate template (NaPAA) before the reaction confirmed that the template polymerization accorded with ZIP I mechanism. The cationic microblock structure and hydrophobic association of TP-ADB promoted the dewatering performance of PD sludge (FCMC = 72.9%, turbidity removal rate = 98.9%, SRF = 4.2 × 1012 m·kg-1). Hydrophobic association enhanced the bridging, sweeping, and net catching effect, and promoted the growth of floc size and fractal dimension. Cationic microblock structure can produce compact floc with higher mechanical strength by enhancing electrical neutralization and electrical patching. As a skeleton, the compressibility of filter cake was reduced and the permeability was enhanced, and the PD sludge dewatering effect was significantly improved.
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Affiliation(s)
- Nianping Chi
- School of Municipal and Geomatics Engineering, Hunan City University, Hunan Province Engineering & Technology Research Center for Rural Water Quality Safety, Hunan, 413000, Yiyang, People's Republic of China
| | - Jiajun Liu
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China
| | - Minghua Lei
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China
| | - Li Feng
- School of Civil and Transportation Engineering, Guangdong University of Technology, No100, Waihuan Xi Road, Guangzhou, Higher Education Mega Center, Panyu District, Guangzhou, 510006, Guangdong, People's Republic of China.
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27
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Xu G, He J. Resilience of organohalide-detoxifying microbial community to oxygen stress in sewage sludge. WATER RESEARCH 2022; 224:119055. [PMID: 36126627 DOI: 10.1016/j.watres.2022.119055] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/20/2022] [Accepted: 09/02/2022] [Indexed: 06/15/2023]
Abstract
Organohalide pollutants are prevalent in the environment, causing harms to wildlife and human. Organohalide-respiring bacteria (OHRB) could detoxify these pollutants in anaerobic environments, but the most competent OHRB (i.e., Dehalococcoides) is susceptible to oxygen. This study reports exceptional resistance and resilience of sewage sludge microbial communities to oxygen stress for attenuation of structurally distinct organohalide pollutants, including tetrachloroethene, tetrabromobisphenol A, and polybrominated diphenyl ethers. The dehalogenation rate constant of these organohalide pollutants in oxygen-exposed sludge microcosms was maintained as 74-120% as that in the control without oxygen exposure. Subsequent top-down experiments clarified that sludge flocs and non-OHRB contributed to alleviating oxygen stress on OHRB. In the dehalogenating microcosms, multiple OHRB (Dehahlococcoides, Dehalogenimonas, and Sulfurospirillum) harboring distinct reductive dehalogenase genes (pceA, pteA, tceA, vcrA, and bdeA) collaborated to detoxify organohalide pollutants but responded differentially to oxygen stress. Comprehensive microbial community analyses (taxonomy, diversity, and structure) demonstrated certain resilience of the sludge-derived dehalogenating microbial communities to oxygen stress. Additionally, microbial co-occurrence networks were intensified by oxygen stress in most microcosms, as a possible stress mitigation strategy. Altogether the mechanistic and ecological findings in this study contribute to remediation of organohalide-contaminated sites encountering oxygen disturbance.
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Affiliation(s)
- Guofang Xu
- Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore; NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, 119077, Singapore
| | - Jianzhong He
- Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore; NUS Graduate School - Integrative Sciences and Engineering Programme (ISEP), National University of Singapore, 119077, Singapore.
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28
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Yao Y, Meng Y, Chen H, Zhu L, Sun H. Non-target discovery of emerging PFAS homologues in Dagang Oilfield: Multimedia distribution and profiles in crude oil. JOURNAL OF HAZARDOUS MATERIALS 2022; 437:129300. [PMID: 35897169 DOI: 10.1016/j.jhazmat.2022.129300] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 06/01/2022] [Accepted: 06/02/2022] [Indexed: 06/15/2023]
Abstract
Per- and polyfluoroalkyl substances (PFASs) are applied in oil exploitation activity. In this study, non-target and suspect target analyses with high-resolution mass spectrometry were used for identification of novel PFASs in the oilfield environment. A total of thirty-seven PFAS homologues belonging to eight classes were identified as level 4 or above, which partly explained the amount of potential unknown PFAS-precursors that were indicated by total oxidisable precursor assay in our previous study. Hydrogen-substituted and ether-substituted homologues were the main identified PFASs, and seven of them were newly reported homologues. C1-C3 perfluoroalkane sulphonic acids (PFSAs) were also for the first time identified in the oilfield. The sediment-water partitioning coefficients of most identified PFAS homologues positively correlate with their predicted octanol-water partitioning coefficients while those of C1-C3 PFSAs may have elevated sediment partitioning potential as also previously observed for ultra-short chain C2-C3 perfluoroalkyl carboxylic acids. The crude oil and sludge samples were further examined with the target and identified PFAS profiles. An annual flux of 10.4 kg/y via oil production was estimated in Dagang Oilfield with 16.6 % not from the target PFASs. This demonstrates that oil exploitation activities can be a significant underlying source of PFASs to the environment.
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Affiliation(s)
- Yiming Yao
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Yue Meng
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Hao Chen
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Lingyan Zhu
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China
| | - Hongwen Sun
- MOE Key Laboratory of Pollution Processes and Environmental Criteria, College of Environmental Science and Engineering, Nankai University, Tianjin 300350, China.
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29
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Xiang Y, Li S, Rene ER, Xiaoxiu L, Ma W. Enhancing fluoroglucocorticoid defluorination using defluorinated functional strain Acinetobacter. pittii C3 via humic acid-mediated biotransformation. JOURNAL OF HAZARDOUS MATERIALS 2022; 436:129284. [PMID: 35739793 DOI: 10.1016/j.jhazmat.2022.129284] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/07/2022] [Accepted: 05/31/2022] [Indexed: 06/15/2023]
Abstract
Defluorination is a key factor in reducing biologically accumulated carcinogenic and teratogenic toxicity of fluoroglucocorticoids (FGCs). To enhance defluorination efficiency, a highly efficient defluorination-degrading strain Acinetobacter. pittii C3 was isolated, and the promotion mechanism through humic acid (HA)-mediated biotransformation was investigated. Optimal biodegradation conditions for Acinetobacter sp. pittii C3 were pH of 7.0, temperature of 25 ℃, and HA content of 5.5 mg/L, according to response surface methodology analysis. The attenuation rate constant and maximum defluorination percentage of triamcinolone acetonide (TA) in HA-mediated biotransformation system (HA-C3) were 3.99 × 10-2 and 96%, respectively, which were 2.22 and 1.24 times higher than those in the unitary C3 biodegradation system (U-C3), respectively. The major defluorination pathways included elimination, hydrolysis, and hydrogenation, with contributions of 24.5%, 32.4%, and 43.1%, respectively. The bio-reductive hydrodefluorination rate was enhanced by 1.89 times that of HA-mediated, while the other two defluorination pathways exhibited insignificant changes. HA, as the congeries of negatively charged microbes and hydrophobic TA, accelerates the electron transfer rate between Acinetobacter. pittii C3 and TA through the quinone groups. Furthermore, the mutual conversion between the functional groups of hydroxyl oxidation and ketone reduction of HA provided electron donors for TA reductive defluorination and hydrogenation and electron acceptors for TA oxidation. This study provides an effective strategy for FGC-enhanced detoxification using natural HA.
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Affiliation(s)
- Yayun Xiang
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Sinuo Li
- Beijing No. 80 High School, Beijing 100102, China
| | - Eldon R Rene
- IHE-Delft, Institute for Water Education, Department of Environmental Engineering and Water Technology, Westvest 7, 2611AX Delft, the Netherlands
| | - Lun Xiaoxiu
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China
| | - Weifang Ma
- College of Environmental Science and Engineering, Beijing Forestry University, Beijing 100083, China.
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30
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Yu Y, Che S, Ren C, Jin B, Tian Z, Liu J, Men Y. Microbial Defluorination of Unsaturated Per- and Polyfluorinated Carboxylic Acids under Anaerobic and Aerobic Conditions: A Structure Specificity Study. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:4894-4904. [PMID: 35373561 PMCID: PMC9465985 DOI: 10.1021/acs.est.1c05509] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The recently discovered microbial reductive defluorination of two C6 branched and unsaturated fluorinated carboxylic acids (FCAs) provided valuable insights into the environmental fate of per- and polyfluoroalkyl substances (PFASs) and potential bioremediation strategies. However, a systematic investigation is needed to further demonstrate the role of C═C double bonds in the biodegradability of unsaturated PFASs. Here, we examined the structure-biodegradability relationships of 13 FCAs, including nine commercially available unsaturated FCAs and four structurally similar saturated ones, in an anaerobic defluorinating enrichment and an activated sludge community. The anaerobic and aerobic transformation/defluorination pathways were elucidated. The results showed that under anaerobic conditions, the α,β-unsaturation is crucial for FCA biotransformation via reductive defluorination and/or hydrogenation pathways. With sp2 C-F bonds being substituted by C-H bonds, the reductive defluorination became less favorable than hydrogenation. Moreover, for the first time, we reported enhanced degradability and defluorination capability of specific unsaturated FCA structures with trifluoromethyl (-CF3) branches at the α/β-carbon. Such FCA structures can undergo anaerobic abiotic defluorination in the presence of reducing agents and significant aerobic microbial defluorination. Given the diverse applications and emerging concerns of fluorochemicals, this work not only advances the fundamental understanding of the fate of unsaturated PFASs in natural and engineered environments but also may provide insights into the design of readily degradable fluorinated alternatives to existing PFAS compounds.
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Affiliation(s)
- Yaochun Yu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Shun Che
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
| | - Changxu Ren
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
| | - Bosen Jin
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
| | - Zhenyu Tian
- College
of Science, Northeastern University, Boston, Massachusetts 02115, United States
| | - Jinyong Liu
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
| | - Yujie Men
- Department
of Chemical and Environmental Engineering, University of California, Riverside, A235 Bourns Hall, 3401 Watkins Drive, Riverside, California 92521, United States
- Department
of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, United States
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Bygd MD, Aukema KG, Richman JE, Wackett LP. Unexpected Mechanism of Biodegradation and Defluorination of 2,2-Difluoro-1,3-Benzodioxole by Pseudomonas putida F1. mBio 2021; 12:e0300121. [PMID: 34781746 PMCID: PMC8593668 DOI: 10.1128/mbio.03001-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 10/12/2021] [Indexed: 12/11/2022] Open
Abstract
Perfluorinated carbon atoms in a diether linkage are common in commercial anesthetics, drugs, fungicides, and insecticides. An important chemical group comprising perfluorodiethers is the 2,2-fluoro-1,3-benzodioxole (DFBD) moiety. The fluorine atoms stabilize the molecule by mitigating against metabolism by humans and microbes, as used in drugs and pesticides, respectively. Pseudomonas putida F1 catalyzed defluorination of DFBD at an initial rate of 2,100 nmol/h per mg cellular protein. This is orders of magnitude higher than previously reported microbial defluorination rates with multiply fluorinated carbon atoms. Defluorination rates declined after several hours, and the medium darkened. Significant defluorination activity was observed with cells grown on toluene but not l-arginine. Defluorination required only toluene dioxygenase. Pseudomonas and recombinant Escherichia coli cells expressing toluene dioxygenase oxidized DFBD to DFBD-4,5-dihydrodiol. The dihydrodiol could be oxidized to 4,5-dihydroxy-DFBD via the dihydrodiol dehydrogenase from P. putida F1. The dihydrodiol dehydrated with acid to yield a mixture of 4-hydroxy-DFBD and 5-hydroxy-DFBD. All those metabolites retained the difluoromethylene group; no fluoride or dark color was observed. The major route of DFBD-4,5-dihydrodiol decomposition produced fluoride and 1,2,3-trihydroxybenzene, or pyrogallol, and that was shown to be the source of the dark colors in the medium. A mechanism for DFBD-4,5-dihydrodiol transformation to two fluoride ions and pyrogallol is proposed. The Pseudomonas genome database and other databases revealed hundreds of bacteria with enzymes sharing high amino acid sequence identity to toluene dioxygenase from P. putida F1, suggesting the mechanism revealed here may apply to the defluorination of DFBD-containing compounds in the environment. IMPORTANCE There are more than 9,000 polyfluorinated compounds developed for commercial use, some negatively impacting human health, and they are generally considered to be resistant to biodegradation. Only a limited number of studies have identified microbes with enzymes sufficiently reactive to defluorinate difluoromethylene carbon groups. The present study examined one important group of commercial fluorinated chemicals and showed its rapid defluorination by a bacterium and its key enzyme, a Rieske dioxygenase. Rieske dioxygenases are common in environmental bacteria, and those closely resembling toluene dioxygenase from Pseudomonas putida F1 are candidates for biodegradative defluorination of the common 2,2-fluoro-1,3-benzodioxole (DFBD) moiety.
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Affiliation(s)
- Madison D. Bygd
- Microbial Engineering, University of Minnesota, St. Paul, Minnesota, USA
| | - Kelly G. Aukema
- Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, USA
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
| | - Jack E. Richman
- Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, USA
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
| | - Lawrence P. Wackett
- Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, Minnesota, USA
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
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Wackett LP. Nothing lasts forever: understanding microbial biodegradation of polyfluorinated compounds and perfluorinated alkyl substances. Microb Biotechnol 2021; 15:773-792. [PMID: 34570953 PMCID: PMC8913905 DOI: 10.1111/1751-7915.13928] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Revised: 09/12/2021] [Accepted: 09/13/2021] [Indexed: 12/20/2022] Open
Abstract
Poly‐ and perfluorinated chemicals, including perfluorinated alkyl substances (PFAS), are pervasive in today’s society, with a negative impact on human and ecosystem health continually emerging. These chemicals are now subject to strict government regulations, leading to costly environmental remediation efforts. Commercial polyfluorinated compounds have been called ‘forever chemicals’ due to their strong resistance to biological and chemical degradation. Environmental cleanup by bioremediation is not considered practical currently. Implementation of bioremediation will require uncovering and understanding the rare microbial successes in degrading these compounds. This review discusses the underlying reasons why microbial degradation of heavily fluorinated compounds is rare. Fluorinated and chlorinated compounds are very different with respect to chemistry and microbial physiology. Moreover, the end product of biodegradation, fluoride, is much more toxic than chloride. It is imperative to understand these limitations, and elucidate physiological mechanisms of defluorination, in order to better discover, study, and engineer bacteria that can efficiently degrade polyfluorinated compounds.
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Affiliation(s)
- Lawrence P Wackett
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, St. Paul, MN, 55108, USA
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