Rebuttal to Correspondence on “Defluorination of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) by <i>Acidimicrobium</i> sp. Strain A6”

Jaffé, Peter R.; Huang, Shan

doi:10.1021/acs.est.3c07853

Cited by 7 publications

(3 citation statements)

References 16 publications

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“…Studies showing microbial or fungal defluorination of PFAAs are limited, have not identified degradation pathways or products, and have not been widely reproduced (Huang & Jaffé, 2019; Kwon et al, 2014; Luo et al, 2015). There is open debate in the industry regarding the validity of some published observations related to biodegradation of PFOA and PFOS (Jaffé & Huang, 2023; Liu et al, 2023). Although biological processes to mineralize PFASs to nontoxic endpoints have not yet been fully demonstrated by multiple researchers, there is hope that ongoing research will discover such processes and lead to lower‐cost, in situ remedies that can destroy PFASs.…”

Section: Biological Approachesmentioning

confidence: 99%

Available and emerging liquid treatment technologies for PFASs

DiGuiseppi,

Newell,

Carey

et al. 2024

Remediation Journal

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Per‐ and polyfluoroalkyl substances (PFASs) are present at a wide range of private sector facilities and United States (US) government installations, including those operated by the Department of Defense, the Department of Energy, the National Aeronauts and Space Administration, and other entities, as well as additional sites worldwide. Impacts have been identified in a range of environmental media including drinking water, groundwater, surface water, leachate, wastewater, soil, sediment, and soil gas. Treatment technologies to remove or destroy PFASs cost effectively have proven to be elusive to the industry. However, recent developments are bringing that goal close to reality for some media. This article has been prepared to address only liquid treatment technologies. Soil treatment technologies are presently a lower priority and may be addressed in future articles. The challenge of identifying and evaluating available and emerging liquid treatment technologies was put to the PFAS Experts Symposium in Houston, Texas, on June 7–8, 2023, which was attended by PFAS professionals and subject matter experts with a broad range of backgrounds. The discussions covered a variety of technical approaches and led to the preparation of this manuscript. This article strives to concisely summarize modern technical approaches that are potentially applicable to managing liquid media at PFAS‐impacted sites. Currently, ex situ sorbent technologies using granular activated carbon (GAC) and ion exchange (IX) resin are commercially available and most widely used. Other liquid technologies are summarized and current applications are presented to allow the reader to evaluate each technology for their particular use. This article is not intended to provide guidance on site‐specific design of treatment systems, but instead to serve as an update to earlier articles from this group and others addressing PFAS treatment technologies and related PFAS topics.

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Section: Biological Approachesmentioning

confidence: 99%

Available and emerging liquid treatment technologies for PFASs

DiGuiseppi,

Newell,

Carey

et al. 2024

Remediation Journal

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“…For example, Acidimicrobium sp. A6 has been reported to defluorinate perfluorinated acids, but the underlying mechanisms and responsible enzyme(s) are yet to be identified 14–16 . Since bioremediation is considered to be a more cost-effective and environmentally friendly approach for in-situ cleanup of PFAS-impacted sites, it is vital to identify defluorinating microorganisms/enzymes and elucidate molecular mechanisms of C–F bond cleavage to allow systems biology and enzyme engineering to progress.…”

Section: Mainmentioning

confidence: 99%

Electron-bifurcation and fluoride efflux systems inAcetobacteriumspp. drive defluorination of perfluorinated unsaturated carboxylic acids

Yu,

Xu,

Zhao

et al. 2023

Preprint

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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 byAcetobacteriumspp. Two critical molecular features inAcetobacteriumspecies 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) onlyAcetobacteriumspp. withcargenes catalyzed defluorination; (ii) caffeate and PFAS competedin 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 by19F-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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“…The defluorination of perfluorinated acids by Acidimicrobium sp. A6 has been reported, but no enzymes responsible for these processes have been identified ( 14 – 16 ). Because bioremediation is considered to be a more cost-effective and environmentally friendly approach for in situ cleanup of PFAS-impacted sites, it is vital to identify defluorinating microorganisms/enzymes and elucidate molecular mechanisms of C─F bond cleavage to allow systems biology and enzyme engineering to progress.…”

Section: Introductionmentioning

confidence: 99%

Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp

Yu,

Xu,

Zhao

et al. 2024

Sci. Adv.

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Enzymatic cleavage of C─F bonds in per- and polyfluoroalkyl substances (PFAS) is largely unknown but avidly sought to promote systems biology for PFAS bioremediation. Here, we report the reductive defluorination of α, β-unsaturated per- and polyfluorocarboxylic acids by Acetobacterium spp. The microbial defluorination products were structurally confirmed and showed regiospecificity and stereospecificity, consistent with their formation by enzymatic reactions. A comparison of defluorination activities among several Acetobacterium species indicated that a functional fluoride exporter was required for the detoxification of the released fluoride. Results from both in vivo inhibition tests and in silico enzyme modeling suggested the involvement of enzymes of the flavin-based electron-bifurcating caffeate reduction pathway [caffeoyl-CoA reductase (CarABCDE)] in the reductive defluorination. This is a report on specific microorganisms carrying out enzymatic reductive defluorination of PFAS, which could be linked to electron-bifurcating reductases that are environmentally widespread.

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Rebuttal to Correspondence on “Defluorination of Perfluorooctanoic Acid (PFOA) and Perfluorooctane Sulfonate (PFOS) by Acidimicrobium sp. Strain A6”

Cited by 7 publications

References 16 publications

Available and emerging liquid treatment technologies for PFASs

Available and emerging liquid treatment technologies for PFASs

Electron-bifurcation and fluoride efflux systems inAcetobacteriumspp. drive defluorination of perfluorinated unsaturated carboxylic acids

Electron bifurcation and fluoride efflux systems implicated in defluorination of perfluorinated unsaturated carboxylic acids by Acetobacterium spp

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