Microbial and Enzymatic Transformation of Per- and Polyfluoroalkyl Substances (PFAS): From Defluorination and Biological Partitioning to a Separation-First Biological Treatment Framework
Aug 2026· Applied Sciences· Vol 16, pp. 7945· 0 citations· 107 references
TL;DR
A separation-first framework in which PFAS are initially captured and concentrated within biological matrices before the application of targeted destruction, regeneration, or residual-management technologies is advanced, potentially reducing treatment volumes and improving overall process sustainability.
Abstract
Per- and polyfluoroalkyl substances (PFAS) are persistent environmental pollutants. Conventional destructive technologies, such as advanced oxidation and electrochemical processes, can achieve partial or complete defluorination. However, their high energy demand, chemical inputs, and operational complexity limit widespread implementation. Increasing evidence indicates that biological systems provide complementary mechanisms for PFAS management through partial biotransformation, defluorination of selected structurally susceptible compounds, and biomass-driven partitioning. This review evaluates the evidence for partial, largely precursor-directed PFAS biotransformation and biocatalytic defluorination through reductive, oxidative, and hydrolytic pathways. It also examines enzymatic carbon–fluorine bond cleavage by fluoroacetate dehalogenases, haloacid dehalogenases, and reductive systems, while recognizing that their demonstrated activity is generally limited to monofluorinated, activated, or polyfluorinated substrates rather than conventional fully perfluorinated PFAS. Laboratory and field observations demonstrate substantial PFAS enrichment within aquatic biomass, including intracellular compartments and extracellular polymeric substances (EPS), indicating that living systems can function as dynamic concentrators that partition PFAS from the aqueous phase. Building on these findings, this review advances a separation-first framework in which PFAS are initially captured and concentrated within biological matrices before the application of targeted destruction, regeneration, or residual-management technologies. By decoupling concentration from transformation, this approach enables independent optimization of each step, potentially reducing treatment volumes and improving overall process sustainability.
Per- and polyfluoroalkyl substances (PFAS) are synthetic fluorinated compounds widely recognized for their stability and persistence in the environment. These characteristics make PFAS valuable in many applications but also pose serious health risks because they do not break down easily. These chemicals can accumulate in living organisms and persist in water systems. PFAS typically transfer from water to other media rather than being completely degraded by conventional treatment technologies such as adsorption and membrane filtration. Chemical degradation techniques, i.e., advanced oxidation processes or electrochemical conversions, require harsh reaction conditions, which make them unsustainable. Microbial degradation offers a green, sustainable alternative for PFAS remediation in water. This review critically analyzes advances in the use of bacterial, fungal, and microbial consortia for PFAS transformation via reductive and oxidative defluorination and/or metabolic reactions. Later, the influence of PFAS structural attributes, i.e., chain length and functional head groups, on microbial activities has been discussed. In the following section, the current progress toward the complete mineralization of PFAS is evaluated. Considering the critical evaluation of microbial degradation processes, several research gaps have been identified, including the lack of detailed mechanistic studies of enzymatic degradation pathways, the need to optimize microbial systems for the sustainable degradation of PFAS, and the integration of biological approaches with other technologies to achieve complete PFAS mineralization. The most important is scaling up microbial techniques by cost evaluation of the process to compete with other physicochemical techniques.
Muhammad Hamza, Nain Tara, Afzal Akram et al.· Applied Sciences· 0 citations
Poly- or perfluorinated organic substances, collectively termed PFAS, are chemicals that contain at least one fully fluorinated carbon atom group. Owing to the strength of the C–F bond and peculiar physical and chemical properties, PFAS are highly persistent and mobile in the environment, and bioaccumulative. In this paper we evaluate the main factors hampering the enzymatic transformation and degradation of PFAS in soil, their potential impact on soil enzyme activity, and discuss possible approaches for evaluating PFAS enzymatic transformation and degradation in soil. We summarise the latest hypotheses and findings on enzymatic defluorination mechanisms, which could explain some PFAS degradation patterns observed in in vitro studies and in soils from contaminated areas, and compare them with the known enzyme catalytic kinetics. We also illustrate the approaches which could be used to analyse the PFAS transformative and biodegradative potential of soil microbial communities, stemming from theoretical considerations and evidence from in silico simulations and laboratory approaches currently used to evaluate PFAS transformation and biodegradation. We also highlight the importance of merging complementary skills and innovative approaches to develop new scientific approaches.
G. Renella, Valentina Quintarelli· Journal of soil science and...· 0 citations
Bacterial dehalogenase enzymes catalyze the cleavage of carbon-halogen bonds and play important roles in the microbial transformation of many halogenated contaminants. This review critically examines major classes of bacterial dehalogenases, including haloalkane dehalogenases, haloacid dehalogenases, fluoroacetate dehalogenases, reductive dehalogenases, and halohydrin dehalogenases, with emphasis on their structural features, catalytic residues, cofactor requirements, substrate specificity, and environmental controls on enzyme activity. Particular attention is given to the relevance and limitations of these enzymes for persistent, fluorinated contaminants, using hexafluoropropylene oxide dimer acid (HFPO-DA, commonly known as GenX) as a case study. Although microbial dehalogenation is well established for many chlorinated and brominated pollutants, direct enzymatic defluorination of GenX remains insufficiently demonstrated. Current evidence suggests that PFAS structure, including strong carbon-fluorine bonds, ether linkages, chain length, and terminal functional groups, strongly constrains microbial and enzymatic transformation. Therefore, this review distinguishes established dehalogenase-mediated organohalide degradation from emerging and still-unverified applications to GenX and related short-chain PFAS. Key research needs include identification of GenX-transforming microorganisms and enzymes, biochemical validation of reaction pathways, kinetic characterization, transformation-product toxicity assessment, enzyme engineering, computational modeling, and scalable hybrid treatment systems. By integrating mechanistic enzymology, environmental operating conditions, and sustainability considerations, this review provides a critical framework for evaluating whether dehalogenase-based approaches can contribute to future PFAS remediation strategies.
D. Kontoh, Dongyang Deng, He Fu et al.· Chemosphere· 0 citations
Per- and polyfluoroalkyl substances (PFASs) are persistent environmental contaminants widely recognized as “forever chemicals” due to the exceptional stability of their carbon–fluorine (C-F) bonds. Their widespread occurrence in water, soil, sediments, and biota, coupled with increasing evidence of toxicity, bioaccumulation, and long-range transport, has intensified the search for sustainable remediation strategies. Conventional remediation technologies for PFASs have been widely applied but remain constrained by several technical and environmental limitations, such as incomplete mineralization, high energy requirements, secondary waste generation, and the formation of toxic transformation products. Moreover, many conventional treatment processes were not originally designed to handle the chemical stability and structural diversity of PFASs, resulting in variable removal efficiencies across different compounds. Bio-based strategies for PFAS remediation, particularly those targeting C-F bond cleavage and biological defluorination, are gaining attention due to the unique challenges posed by the chemical stability and environmental persistence of these “forever chemicals”. This review addresses the fragmented nature of PFAS remediation research by integrating biological and physicochemical strategies and critically examining mechanisms of C-F bond cleavage and defluorination. Emerging technologies, including bioelectrochemical systems, photocatalytic and electrochemical defluorination, adsorption-assisted degradation, plasma treatment, hydrothermal processes, and synthetic biology approaches, are evaluated in relation to their degradation efficiencies, defluorination capacities, and applicability in diverse environmental matrices. Particular attention is given to integrated “capture-and-destroy” systems that combine adsorption with catalytic or biological degradation to enhance remediation efficiency and reduce energy demand. PFAS treatment performance varies markedly across scalability, destruction, and cost. Key knowledge gaps and future perspectives are outlined, emphasizing the need for scalable, energy-efficient, and environmentally sustainable remediation technologies capable of achieving complete PFAS mineralization in complex environmental systems.
C. R. Ohoro, V. Ngole-jeme· Separations· 0 citations
Per- and polyfluoroalkyl substances (PFAS) were widely recognized as emerging environmental pollutants due to their extensive distribution across ecosystems. PFAS were synthetic chemicals composed of alkyl chains bonded to multiple fluorine atoms, and they had been detected in various environmental compartments, including rivers, soil, oceans, and the atmosphere. These compounds originated from a wide range of industrial and consumer products such as textiles, non-stick cookware, aqueous film-forming foams (AFFFs), and cosmetics. Once released into the environment, PFAS persisted for long periods and exhibited toxic effects on both ecosystems and human health. The exceptional stability of PFAS was attributed to the strong carbon–fluorine (C–F) bonds, which were among the strongest in organic chemistry due to fluorine’s high electronegativity. As a result, PFAS were commonly referred to as “forever chemicals” because of their extreme resistance to degradation. Their persistence and bioaccumulative properties had made PFAS contamination a global environmental and public health concern. In response, various source reduction strategies were implemented, including the substitution of PFAS with alternative chemicals, regulatory policies, and increased consumer awareness. In parallel, green chemistry had emerged as a promising approach for developing safer and more sustainable alternatives, such as biopolymers, fluorine-free materials, and short-chain PFAS substitutes. However, further research was still required to improve the performance, safety, and scalability of these alternatives. This study aimed to discuss the sources and environmental impacts of PFAS, evaluate source reduction strategies, and examine green chemistry-based alternatives. It also identified key challenges and outlined future research directions needed to enhance the development and implementation of effective PFAS replacements.
R. A. Kristanti, Yan Li, Putri Adia Utari· Tropical Aquatic and Soil Po...· 0 citations
Per- and polyfluoroalkyl substances (PFASs) are persistent, surface-active contaminants for which soil represents the largest terrestrial reservoir. This review synthesizes a rapidly expanding but fragmented body of literature in order to reframe PFAS not merely as a groundwater transport problem but as a systemic stressor of soil health, drawing together their reported effects on the chemical, physical and biological properties of soils and giving particular attention to the calcareous, alkaline, carbon-poor and seasonally dry soils of the Mediterranean. The reviewed evidence suggests that, chemically, PFASs perturb the coupled carbon and nitrogen cycles rather than the bulk soil reaction, transiently stimulating and then depressing organic carbon turnover, drawing down the dissolved organic carbon pool and disturbing nitrification, while their retention and bioavailability are governed chiefly by organic carbon, chain length and pH. Physically, the surfactant character that defines these molecules lowers the surface tension of soil water and concentrates PFASs at the air–water interface, so that in unsaturated and drought-prone soils much of the burden is retained and then released episodically, most clearly on rewetting after dry periods. Biologically, the literature consistently reports dose-dependent declines in microbial viability, diversity and enzyme activity, alongside toxicity to earthworms and other soil fauna, with sensitivity strongly modulated by soil texture and organic matter. Across all three domains, the Mediterranean emerges as both potentially vulnerable and conspicuously understudied, the available data being clustered in a few western countries and effectively absent for much of the eastern and southern basin, so that the regional assessment offered here rests largely on mechanistic inference rather than on direct observation. The review argues that these coupled mechanistic and geographic gaps define an urgent, region-specific research agenda for the protection of soil health.
Traianos Minos, Alkiviadis Stamatakis, Evangelia E. Golia· Pollutants· 0 citations