Eco-Friendly Biocatalysts: Laccase Applications, Innovations, and Future Directions in Environmental Remediation

Abstract

Laccases, a class of multicopper oxidases found in diverse biological sources, have emerged as key green biocatalysts with significant potential for eco-friendly pollutant degradation. Their ability to drive electron transfer reactions using oxygen, converting pollutants into less harmful products, positions laccases as promising tools for scalable and sustainable treatment of wastewater, soil, and air pollution. This review explores laccase from a translational perspective, tracing its journey from laboratory discovery to real-world applications. Emphasis is placed on recent advances in production optimization, immobilization strategies, and nanotechnology-enabled enhancements that have improved enzyme stability, reusability, and catalytic efficiency under complex field conditions. Applications are critically discussed for both traditional pollutants such as synthetic dyes, phenolics, and pesticides and emerging contaminants, including endocrine-disrupting chemicals, pharmaceuticals, personal care products, microplastic additives, and PFAS. Special attention is given to hybrid systems integrating laccase with advanced oxidation processes, bioelectrochemical systems, and renewable energy-driven reactors to achieve near-complete pollutant mineralization. Challenges such as cost–benefit limitations, limited substrate range without mediators, and regulatory hurdles are evaluated alongside solutions including protein engineering, mediator-free laccase variants, and continuous-flow bioreactors. By consolidating recent mechanistic insights, this study underscores the translational pathways of laccase, highlighting its potential as a cornerstone of next-generation, scalable, and eco-friendly remediation technologies aligned with circular bioeconomy and low-carbon initiatives.

1. Introduction

The exponential rise in industrialization, urban sprawl, and population growth has resulted in an alarming increase in environmental pollutants, including synthetic dyes, pesticides, pharmaceuticals, and endocrine-disrupting compounds (EDCs) [1]. Traditional physicochemical remediation approaches, such as incineration, chemical oxidation, and adsorption, are often energy-intensive, costly, and prone to generating secondary pollutants that pose further risks to ecosystems and human health [2,3]. In pursuit of greener alternatives, biocatalysts have emerged as powerful tools for addressing these environmental challenges, with laccase standing out as a versatile and eco-friendly enzyme [4].

Laccases (EC 1.10.3.2) are multicopper oxidases found in fungi, bacteria, plants, and some insects. They catalyze the oxidation of a wide range of phenolic and non-phenolic compounds, reducing molecular oxygen to water [5]. Their broad substrate flexibility and ability to act on recalcitrant pollutants especially in the presence of redox mediators make them strong candidates for remediation technologies. Unlike conventional methods, laccase-driven processes are biodegradable, non-toxic, and compatible with ambient conditions, aligning with the global demand for sustainable practices [6]. Among microbial sources, fungal laccases, particularly those from white-rot fungi such as Trametes versicolor are extensively studied due to their high redox potential and efficient degradation capabilities [7]. Recent advances in microbial biotechnology and synthetic biology have further improved yields through heterologous expression and directed evolution. Breakthroughs in immobilization, nanomaterial integration, and bioreactor design have also enhanced stability and reusability, paving the way for scalable industrial applications [8].

Laccase has emerged as a powerful biocatalyst for sustainable environmental remediation, demonstrating high efficiency in degrading diverse contaminants under mild and eco-friendly conditions. It has been successfully applied in wastewater treatment, breaking down synthetic dyes from textile effluents, phenolic compounds from paper mill discharges, and residual antibiotics and hormones from pharmaceutical waste [9]. Beyond water treatment, laccase contributes to soil restoration by oxidizing persistent organic pollutants, pesticides, and lignin derivatives, thus helping to reestablish ecological balance [10]. Recent studies have expanded its applications to solid waste detoxification, air purification, and the development of biosensors for real-time contaminant monitoring [11]. What distinguishes laccase from conventional physicochemical approaches is its ability to use molecular oxygen as the final electron acceptor, generating water as the main by-product and minimizing secondary pollution. Despite these advantages, challenges remain such as pH and thermal sensitivity, limited substrate specificity without mediators, and high production costs, which currently restrict its full-scale industrial implementation. This review highlights laccase’s biochemical mechanisms, microbial and recombinant production strategies, and its translational potential, emphasizing innovations that could position laccase as a cornerstone technology in circular and low-carbon remediation systems.

2. Microbial Sources and Production of Laccase

Laccases are widely distributed multicopper oxidases produced by a diverse range of organisms, including fungi, bacteria, actinomycetes, plants, and even certain insects [12]. Among these, microbial laccases, particularly those of fungal origin are the most extensively studied due to their high redox potential and broad substrate specificity. White-rot fungi such as T. versicolor, Pleurotus ostreatus, Ganoderma lucidum, and Phanerochaete chrysosporium produce large quantities of extracellular laccases for lignin degradation, making them industrially relevant [13]. Bacterial and actinomycete laccases offer additional advantages such as thermostability and activity at alkaline pH [14,15]. Plant-derived laccases, first discovered in Rhus vernicifera (Japanese lacquer tree), play key roles in lignin biosynthesis and wound healing, and their potential for biotechnological applications is increasingly being recognized [16] (Table 1). Insects, including some termites and mosquitoes, also produce laccase-like multicopper oxidases involved in cuticle sclerotization and pigment formation, suggesting an underexplored resource for novel enzymes. This diverse biological origin underscores the potential for bioprospecting and enzyme engineering to tailor laccase properties for specific environmental and industrial applications.

The level of laccase production depends strongly on the microbial strain, culture conditions, and inducers [12]. Both solid-state and submerged fermentation are commonly applied in large-scale production. Solid-state fermentation, often using agricultural residues such as wheat bran, rice straw, or sawdust, is particularly cost-effective for fungal laccases [17]. Addition of copper ions or aromatic compounds like xylidine and guaiacol can serve as strong inducers, markedly enhancing enzyme synthesis [18]. In recent years, recombinant DNA technology has revolutionized laccase production. Expression of laccase genes in heterologous hosts such as Escherichia coli and Saccharomyces cerevisiae has enabled higher yields and provided opportunities to tailor enzyme properties [19]. Optimization of parameters such as pH, temperature, aeration, and nutrient composition further improves productivity. Overall, microbial laccases represent versatile biocatalysts, and ongoing efforts in strain improvement, genetic engineering, and process optimization are critical for scaling up their use in both environmental and industrial applications. Although recombinant expression in E. coli and S. cerevisiae provides opportunities for high-yield and tailored laccase variants through protein engineering, their current yields remain lower than required for large-scale environmental remediation, making production cost a major hurdle. This challenge highlights the need for strain engineering, fed-batch optimization, and use of cost-effective substrates to bridge the gap between laboratory success and industrial implementation. Table 2 summarizes the production of laccases from different sources, highlighting key parameters that are important for translational and industrial applications.

Table 1. Microbial and Plant-Derived Laccases: Sources and Applications.

Organism	Origin	Application in Environmental Remediation	Reference
Trametes versicolor	White-rot fungus	Decolorization of azo and anthraquinone dyes, removal of phenols	[7]
Pleurotus ostreatus	White-rot fungus	Degradation of lignin, pesticides and pharmaceutical resides	[13]
Bacillus subtilis	Bacterium	Phenol and bisphenol A degradation at neutral pH	[14]
Azospirillum lipoferum	Bacterium	Dye degradation under alkaline conditions	[15]
Rhus vernicifera	Plant	Lignin biosynthesis, potential in phenol degradation	[12]
Bemisia tabaci	Insect	Cuticle sclerotization, potential for bioremediation	[20]

Table 1. Microbial and Plant-Derived Laccases: Sources and Applications.

Organism	Origin	Application in Environmental Remediation	Reference
Trametes versicolor	White-rot fungus	Decolorization of azo and anthraquinone dyes, removal of phenols	[7]
Pleurotus ostreatus	White-rot fungus	Degradation of lignin, pesticides and pharmaceutical resides	[13]
Bacillus subtilis	Bacterium	Phenol and bisphenol A degradation at neutral pH	[14]
Azospirillum lipoferum	Bacterium	Dye degradation under alkaline conditions	[15]
Rhus vernicifera	Plant	Lignin biosynthesis, potential in phenol degradation	[12]
Bemisia tabaci	Insect	Cuticle sclerotization, potential for bioremediation	[20]

Table 2. Comparative analysis of laccase production systems and their industrial relevance.

Production System	Optimal Conditions	Advantages	Limitations/Challenges	Industrial Relevance
Fungal Laccases (T. versicolor, P. ostreatus)	pH 3–6, 25–35 °C, copper/phenolic inducers	High catalytic efficiency, broad substrate range	Slow growth, complex regulation, sensitive to culture conditions	Widely used for dye decolorization, wastewater treatment, soil remediation
Bacterial Laccases (B. subtilis, P. putida)	pH 5–8, 30–60 °C	Better tolerance to alkaline pH, high thermal stability, easy genetic manipulation	Lower activity compared to fungal laccases, narrow substrate range	Ideal for alkaline effluents, high-temperature processes
Plant Laccases (e.g., Zea mays, Arabidopsis thaliana)	Plant growth-dependent	Naturally abundant in plant tissues	Difficult to extract/purify in large quantities, low yield	Potential use in lignin valorization and biomass conversion
Recombinant Expression in E. coli	Controlled fermentation, induction (IPTG)	Rapid growth, easy genetic engineering, scalable	Requires refolding steps for active enzyme, low secretion, yields still below industrial demand	Suitable for tailored enzyme design, but cost-intensive
Recombinant Expression in S. cerevisiae	pH 5–6, 28–30 °C	Produces active, glycosylated laccase similar to fungal form	Lower yield compared to native fungal hosts, requires optimization	Promising for large-scale production with process intensification
Other Heterologous Systems (Pichia pastoris, Aspergillus niger)	pH 4–6, optimized aeration	Higher expression than S. cerevisiae, scalable fermentation	Requires codon optimization and process control	Emerging platform for industrial-grade laccase production

Table 2. Comparative analysis of laccase production systems and their industrial relevance.

Production System	Optimal Conditions	Advantages	Limitations/Challenges	Industrial Relevance
Fungal Laccases (T. versicolor, P. ostreatus)	pH 3–6, 25–35 °C, copper/phenolic inducers	High catalytic efficiency, broad substrate range	Slow growth, complex regulation, sensitive to culture conditions	Widely used for dye decolorization, wastewater treatment, soil remediation
Bacterial Laccases (B. subtilis, P. putida)	pH 5–8, 30–60 °C	Better tolerance to alkaline pH, high thermal stability, easy genetic manipulation	Lower activity compared to fungal laccases, narrow substrate range	Ideal for alkaline effluents, high-temperature processes
Plant Laccases (e.g., Zea mays, Arabidopsis thaliana)	Plant growth-dependent	Naturally abundant in plant tissues	Difficult to extract/purify in large quantities, low yield	Potential use in lignin valorization and biomass conversion
Recombinant Expression in E. coli	Controlled fermentation, induction (IPTG)	Rapid growth, easy genetic engineering, scalable	Requires refolding steps for active enzyme, low secretion, yields still below industrial demand	Suitable for tailored enzyme design, but cost-intensive
Recombinant Expression in S. cerevisiae	pH 5–6, 28–30 °C	Produces active, glycosylated laccase similar to fungal form	Lower yield compared to native fungal hosts, requires optimization	Promising for large-scale production with process intensification
Other Heterologous Systems (Pichia pastoris, Aspergillus niger)	pH 4–6, optimized aeration	Higher expression than S. cerevisiae, scalable fermentation	Requires codon optimization and process control	Emerging platform for industrial-grade laccase production

3. Biochemical Properties and Catalytic Mechanisms of Laccase

Laccase catalyzes the one-electron oxidation of a broad range of phenolic and non-phenolic substrates while simultaneously reducing molecular oxygen to water [5] (Figure 1). Its catalytic center contains four copper atoms arranged in three distinct sites: Type 1 (T1) copper, responsible for accepting electrons from the substrate; Type 2 (T2) copper; and binuclear Type 3 (T3) coppers, which together form the trinuclear T2/T3 cluster where oxygen is reduced (Figure 1) [21]. The process begins when the substrate donates an electron to the T1 copper site, creating a radical intermediate. The electron is then transferred internally to the T2/T3 cluster, which receives four electrons in total during a full catalytic cycle. At the cluster, molecular oxygen is reduced to two molecules of water, completing the redox cycle. This elegant mechanism allows laccase to function under mild, environmentally friendly conditions, with oxygen serving as the final electron acceptor and water as the byproduct. The ability of laccase to generate reactive radicals enables subsequent breakdown or polymerization of complex pollutants, making it highly versatile for applications in wastewater treatment, soil detoxification, and bioremediation of recalcitrant compounds.

Laccase typically shows strong activity toward phenolic and polyphenolic compounds, especially those bearing hydroxyl groups on aromatic rings [22]. Laccases alone are often unable to oxidize non-phenolic substrates or high-redox-potential pollutants due to thermodynamic and steric limitations [23]. To overcome this, redox mediators are employed as small, diffusible compounds that act as electron shuttles between the enzyme and otherwise inaccessible substrates. The laccase first oxidizes the mediator into a stable radical or cation, which then diffuses to oxidize the target pollutant, effectively broadening the enzyme’s substrate range and enhancing reaction rates. Commonly used synthetic mediators include 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 1-hydroxybenzotriazole (HBT), both of which are widely utilized in dye decolorization and xenobiotic degradation studies. Other examples are violuric acid (VLA), TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl), and syringaldehyde, a natural mediator derived from lignin degradation. These mediators can improve the transformation efficiency of pharmaceuticals (e.g., diclofenac, carbamazepine), pesticides, and persistent organic pollutants under mild environmental conditions. Natural mediators such as acetosyringone, vanillin, and p-coumaric acid are gaining attention as greener alternatives due to their lower toxicity and reduced risk of secondary pollution [24]. However, the potential ecotoxicity and cost of synthetic mediators must be considered when designing laccase-based remediation systems, making the search for sustainable, low-cost, and mediator-free laccase variants an active research frontier.

The optimal activity of laccase depends on environmental conditions. Most fungal laccases function best in mildly acidic pH (3–6), while bacterial enzymes may retain activity under neutral or alkaline conditions [25]. Temperature stability also varies as thermostable bacterial laccases and engineered variants can withstand elevated temperatures, making them highly suitable for industrial applications [26]. Importantly, laccase is recognized for its low substrate specificity, enabling it to act on a wide array of compounds [27]. Its reliance on atmospheric oxygen as the final electron acceptor further simplifies applications, as no additional chemical inputs are required. In summary, laccase’s unique multicopper structure, broad catalytic capacity, and eco-friendly mechanism make it a highly promising biocatalyst for breaking down pollutants across water, soil, and industrial waste environments.

4. Laccase in Environmental Remediation: From Common Pollutants to Emerging Contaminants

Laccases have emerged as one of the most promising biocatalysts for environmental remediation owing to their ability to oxidize a wide range of organic and inorganic compounds under mild and eco-friendly conditions (Figure 2, Table 3) [6,11]. Unlike conventional physicochemical treatments that require harsh reagents or extreme operating conditions, laccases employ molecular oxygen as the terminal electron acceptor, generating water as the reduction product of oxygen. However, rather than achieving complete mineralization, laccase-catalyzed reactions often yield partially oxidized or polymerized intermediates with reduced toxicity and enhanced biodegradability. These transformation products facilitate subsequent microbial degradation and make laccase-based systems particularly valuable as a sustainable pretreatment step or as a complementary component of integrated remediation strategies. Their low substrate specificity and ability to act on both phenolic and non-phenolic compounds broaden their applicability, particularly for pollutants resistant to conventional degradation.

4.1. Traditional Pollutants: Dyes, Phenolics, and Pesticides

Synthetic dyes are among the most visible pollutants, especially in textile effluents, where their persistence and toxicity pose ecological hazards. Many dyes contain aromatic amines and azo linkages, which are resistant to microbial degradation. Laccases initiate dye degradation by abstracting electrons from hydroxylated aromatic rings, generating phenoxy radicals that undergo cleavage or polymerization (Figure 2). The loss of conjugation in chromophores leads to visible decolorization, often accompanied by reduced toxicity. T. versicolor laccase, for example, has achieved >90% decolorization of azo and anthraquinone dyes within hours [28,29]. When used with mediators, laccases extend their activity to non-phenolic dye components, making them suitable for treatment of complex textile effluents.

Phenolic pollutants, widely generated from pulp and paper industries, oil refineries, and tanneries, are not only toxic to aquatic organisms but also bioaccumulate through food chains. Laccase oxidizes phenols to reactive quinones, which polymerize into insoluble aggregates that can be separated from water. Importantly, this reaction not only detoxifies but can also valorize phenolic wastes by producing biopolymers with applications in coatings and packaging [30]. Thus, laccase provides a dual benefit, including remediation and resource recovery.

Persistent pesticides such as chlorophenols, organophosphates, and carbamates are heavily used in agriculture and persist in both soils and groundwater. Laccase-based treatments degrade pesticides by oxidizing aromatic hydroxyl groups, destabilizing molecular structures, and rendering them more susceptible to microbial mineralization. Immobilized laccase systems further enhance pesticide degradation by improving enzyme stability and reusability. For example, laccase immobilized on magnetic nanoparticles has achieved remarkable chlorpyrifos degradation under optimized conditions [31]. Such systems highlight the potential for scalable field applications in soil and groundwater bioremediation.

4.2. Emerging Contaminants: Pharmaceuticals, EDCs, PCPs, Microplastics, and PFAS

While laccases have long been applied to traditional pollutants, the recent emergence of new classes of contaminants has broadened their scope of application (Table 3). Modern industrial, agricultural, and consumer practices have introduced substances such as pharmaceuticals, personal care products (PCPs), endocrine disrupting chemicals (EDCs), microplastics, and Per- and polyfluoroalkyl substances (PFAS), which persist at trace concentrations but exert profound and long-term ecological and health impacts [32,33]. Conventional wastewater treatment systems are often inadequate for these pollutants, making biocatalytic solutions increasingly important. Pharmaceuticals are now frequently detected in water bodies worldwide, ranging from antibiotics and anti-inflammatory drugs to antidepressants and hormonal therapies [34]. Their persistence leads to accumulation, with risks such as the spread of antimicrobial resistance and endocrine disruption in aquatic organisms. Laccase catalyzes the transformation of pharmaceuticals such as diclofenac and carbamazepine into hydroxylated or polymerized forms with reduced biological activity [35].

EDCs, including bisphenols and phthalates, disrupt hormonal systems at even nanogram concentrations, causing reproductive and developmental issues in humans and wildlife [36,37]. Laccase-mediated polymerization of bisphenol A generates dimers and oligomers with reduced estrogenic activity, reducing ecological risks [38]. Future directions focus on protein engineering to modify laccase’s active site, enabling efficient oxidation of bulky hydrophobic EDCs. Such advances could pave the way for engineered enzymes designed specifically to remove EDCs from wastewater streams.

PCPs such as triclosan, parabens, and UV filters (e.g., oxybenzone) are increasingly recognized as aquatic pollutants with adverse ecological impacts [39]. Triclosan, in particular, is linked to antimicrobial resistance and hormonal disruption [40]. Laccase transforms triclosan into chlorinated dimers and oligomers with reduced toxicity. When coupled with microbial consortia, these intermediates undergo further mineralization, offering a synergistic route for complete remediation [41]. This integrated enzymatic–microbial treatment approach illustrates how laccase can serve as the first step in pollutant detoxification, mimicking natural biodegradation cascades.

Microplastics are a growing environmental concern, not only as physical pollutants but also as carriers of hazardous additives such as bisphenols, phthalates, and flame retardants [42]. While laccase cannot degrade polymeric microplastic particles, it can oxidize the additives leaching into water, reducing toxicity. Innovative approaches propose immobilizing laccase on porous carriers with high surface areas. These carriers can both capture microplastic particles and detoxify leached chemicals, providing a dual-function remediation system. Such strategies demonstrate how enzymatic systems can be tailored to address emerging multi-pollutant challenges. Per- and polyfluoroalkyl substances (PFAS) are among the most recalcitrant pollutants due to their extremely stable C–F bonds [43]. PFAS resist biodegradation, accumulating in soils, water, and organisms. Laccase alone cannot mineralize PFAS, but it can oxidize precursor molecules or partially transform PFAS derivatives into more labile intermediates. Hybrid remediation approaches are being explored where laccase initiates partial oxidation, followed by advanced oxidation processes (e.g., photocatalysis, ozonation). These systems leverage enzymatic selectivity and chemical aggressiveness in tandem, offering one of the few feasible strategies for PFAS degradation at environmentally relevant concentrations.

4.3. Broader Environmental Applications

Beyond the direct degradation of common and emerging pollutants, laccase also plays a pivotal role in diverse remediation strategies that extend across soil, air, solid waste, industrial effluents, and even environmental monitoring systems. Its versatility stems from its broad substrate range, eco-friendly mode of action, and compatibility with both biological and engineered systems, allowing it to address multiple environmental challenges simultaneously. In soils, laccase contributes to the detoxification of pesticides and polycyclic aromatic hydrocarbons (PAHs). By oxidizing aromatic structures, the enzyme reduces toxicity and transforms pollutants into more hydrophilic intermediates. These products are then more accessible to native microbial communities, which complete the mineralization process [44]. This cooperative action between laccase and soil microbiota enhances the natural resilience of contaminated ecosystems, offering a sustainable route for restoring soil health.

Laccase has also been incorporated into biofiltration systems for air treatment, where it facilitates the removal of volatile organic compounds (VOCs) such as phenols and styrene. VOCs are a major concern in industrial emissions due to their carcinogenic and toxic effects. Laccase-based biofilters not only reduce these VOCs but also simultaneously neutralize odor-causing thiols, sulfides, and amines, making them useful for both industrial and urban air purification [45]. Agricultural and agro-industrial wastes often contain phenolic inhibitors that limit their reuse and slow down composting. Laccase detoxifies these residues by oxidizing phenolic compounds, thereby accelerating compost maturation, improving quality, and enabling safe reuse. Moreover, in processes such as lignocellulosic biomass conversion, laccase removes inhibitors from hydrolysates, enhancing downstream microbial fermentation for biofuels and chemicals [46]. This dual function waste detoxification and valorization aligns with circular economy goals.

Heavy metals often exist in wastewater as metal–organic complexes with dyes or ligands that stabilize them, making removal challenging. Laccase indirectly aids in metal remediation by oxidizing the organic ligands, destabilizing these complexes, and facilitating subsequent precipitation or adsorption of metals. Advanced designs, such as metal–organic frameworks (MOFs) for enzyme immobilization, enhance this process by improving laccase stability and reusability [47]. This synergy between enzymatic oxidation and separation technologies provides a sustainable approach for metal–organic pollutant removal.

The oxidative activity of laccase has been harnessed in the development of sensitive biosensors for environmental monitoring. By coupling enzymatic reactions with electrochemical transducers, laccase-based biosensors can detect phenols, pesticides, and pharmaceuticals in real time. These devices provide rapid, cost-effective alternatives to conventional analytical methods. For example, laccase bioconjugates with carbon nanotubes have been applied for the detection of bisphenol A, while laccase–nanotube systems enable near real-time analysis of para-cresol in wastewater [48,49]. These biosensors not only support pollution control but also facilitate continuous environmental surveillance.

Table 3. Environmental applications of Laccase.

Application Area	Pollutant Type	Laccase Source	Outcome	Reference
Wastewater Treatment—Dye Removal	Reactive black, reactive red, azo dyes	Trametes versicolor	>90% decolorization within hours	[50]
Wastewater Treatment—Phenolic Compounds	Phenol, chlorophenol	Pleurotus ostreatus	85% phenol removal in pulp mill effluent	[51]
Pharmaceutical Residue Removal	Diclofenac, carbamazepine, ethinylestradiol	Ganoderma lucidum	>80% removal, reduced estrogenic activity	[52]
Soil Bioremediation—Pesticides	Chlorpyrifos, carbamate pesticides	Immobilized T. versicolor	Significant degradation, reduced toxicity	[53]
Soil Bioremediation—PAHs	Benzo[a]pyrene, anthracene	Bacterial laccase	Transformation to less toxic derivatives	[54]
Air Pollution Control—VOCs	Phenol vapors, styrene	Laccase biofilter	Reduced VOC concentration	[55]
Solid Waste Management—Composting	Lignin-rich residues	Laccase-producing consortia	Faster compost maturity, improved quality	[56]
EDC Removal	Bisphenol A	Immobilized fungal laccase	Continuous BPA removal	[57]
Heavy Metal–Organic Complex Breakdown	Dye-metal complexes	Laccase + mediators	Disruption of complexes, improved metal precipitation	[58]
Personal Care Products (PCPs)	Triclosan, parabens, and oxybenzone	Bacterial laccase Fungal laccase	Removal of PCPs	[59,60]
Per- and polyfluoroalkyl substances (PFAS)	PFAS compounds	Fungal laccase	Defluorination and degradation of PFAS	[61]
Biosensing	Phenols, pesticides	Laccase-based electrode	Detection at nanomolar concentrations	[62]

Table 3. Environmental applications of Laccase.

Application Area	Pollutant Type	Laccase Source	Outcome	Reference
Wastewater Treatment—Dye Removal	Reactive black, reactive red, azo dyes	Trametes versicolor	>90% decolorization within hours	[50]
Wastewater Treatment—Phenolic Compounds	Phenol, chlorophenol	Pleurotus ostreatus	85% phenol removal in pulp mill effluent	[51]
Pharmaceutical Residue Removal	Diclofenac, carbamazepine, ethinylestradiol	Ganoderma lucidum	>80% removal, reduced estrogenic activity	[52]
Soil Bioremediation—Pesticides	Chlorpyrifos, carbamate pesticides	Immobilized T. versicolor	Significant degradation, reduced toxicity	[53]
Soil Bioremediation—PAHs	Benzo[a]pyrene, anthracene	Bacterial laccase	Transformation to less toxic derivatives	[54]
Air Pollution Control—VOCs	Phenol vapors, styrene	Laccase biofilter	Reduced VOC concentration	[55]
Solid Waste Management—Composting	Lignin-rich residues	Laccase-producing consortia	Faster compost maturity, improved quality	[56]
EDC Removal	Bisphenol A	Immobilized fungal laccase	Continuous BPA removal	[57]
Heavy Metal–Organic Complex Breakdown	Dye-metal complexes	Laccase + mediators	Disruption of complexes, improved metal precipitation	[58]
Personal Care Products (PCPs)	Triclosan, parabens, and oxybenzone	Bacterial laccase Fungal laccase	Removal of PCPs	[59,60]
Per- and polyfluoroalkyl substances (PFAS)	PFAS compounds	Fungal laccase	Defluorination and degradation of PFAS	[61]
Biosensing	Phenols, pesticides	Laccase-based electrode	Detection at nanomolar concentrations	[62]

5. Immobilization and Stability Enhancement Techniques for Laccase

Laccase, a widely used biocatalyst in environmental applications, often suffers from limitations such as low operational stability, sensitivity to pH and temperature changes, and loss of activity over time. To overcome these challenges and extend its usability in large-scale processes, various immobilization strategies and stability enhancement techniques have been developed (Figure 3). Immobilizing laccase enhances its stability, reusability, and overall efficiency, making it more suitable industrial and wastewater treatment applications [63].

5.1. Immobilization Techniques

Immobilization methods for laccase are classified into distinct categories. Physical methods such as adsorption and entrapment are simple and low-cost, though often less stable. Chemical methods, including covalent binding and cross-linking, offer stronger attachment and durability, while nanotechnology-based approaches are emerging as highly effective alternatives.

5.1.1. Physical Adsorption

This is the simplest method, where laccase molecules are adsorbed onto carriers such as activated carbon, silica gel, chitosan, or biochar through weak forces like Vander Waals interactions, hydrogen bonds, and electrostatic attractions [64]. Though inexpensive and easy to perform, the major drawback is enzyme leaching due to weak binding, especially under changing pH or ionic strength. Laccase adsorbed onto biochar derived from agricultural waste showed substantial dye decolorization efficiency in textile wastewater treatment [65,66]. Metal-chelated adsorption is a technique where metal ions are covalently linked to histidine (His) or cysteine (Cys) residues on the enzyme surface, enabling efficient and oriented immobilization. For instance, laccase immobilized on Cu2+-chelated zinc oxide (ZnO) and manganese oxide (MnO2) nanoparticles showed nearly double the catalytic activity compared to free laccase, achieving 95% and 85% degradation of alizarin red S dye, respectively [67,68]. Affinity-based adsorption exploits the natural binding of laccase glycans to supports. Using Concanavalin A-functionalized carbon nanotubes, laccase can be immobilized directly from crude extracts, reducing purification steps and preserving activity [69].

5.1.2. Covalent Binding

In this method, laccase is chemically attached to the support via covalent bonds, usually involving functional groups such as –NH₂, –COOH, or –OH on the support surface [70]. Supports such as glutaraldehyde (GA)-activated agarose, epoxy resins, and amino-functionalized silica are among the most frequently used carriers for laccase immobilization, as they offer strong covalent attachment, improved thermal stability, and reduced enzyme leaching, making them suitable for repeated cycles of biocatalysis [8,71,72]. Functionalized magnetic mesoporous silica nanoparticles chelated with Cu(2+) enabled efficient laccase immobilization, showing high adsorption capacity, catalytic efficiency, and enhanced stability [73]. Covalent immobilization involves activating functional groups on the support surface with cross-linking agents, which then bind to enzyme amino groups to form stable covalent bonds. For instance, Kuznetsov et al. modified a glassy carbon electrode with oxygen plasma to introduce carboxyl groups, activated them with Carboxymethyl cellulose (CMC), and immobilized laccase by simple incubation in PBS [74]. Patel et al. evaluated covalent immobilization of laccase on silica nanoparticles functionalized with different groups—aldehyde (via GA), carbodiimide (via 1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide metho-p-toluenesulfonate), and cyanogen (via cyanogen bromide) under identical conditions [75]. Supports functionalized with aldehyde groups achieved the highest immobilization yield (73.2%) and efficiency (78.4%), followed by carbodiimide-activated supports (64.5% and 64.2%) and cyanogen-activated supports, which showed the lowest values (56.45% and 61.4%). Covalent attachment provides strong binding and reduced leaching but may sometimes alter the enzyme’s active site, leading to reduced activity.

5.1.3. Entrapment and Encapsulation

Entrapment involves trapping laccase within a polymeric or gel matrix, such as calcium alginate, polyacrylamide, or agar [76]. While it provides good protection from environmental stress, mass transfer limitations and enzyme leakage can be concerns. Laccase from Lentinus sajor-caju immobilized on halloysite nanotubes and entrapped in chitosan beads achieved high immobilization yield and protein loading, effectively enabling the degradation of sulfamethoxazole, tetracycline, and acetaminophen in water [77]. Makas et al. entrapped laccase in κ-carrageenan semi-interpenetrating polymer networks, maintaining its optimal pH and temperature. The immobilized enzyme retained 82% activity after 42 days of storage and over 50% activity after 10 reuse cycles, demonstrating excellent stability and reusability [78]. The efficiency of entrapment largely depends on the pore size of the support as pores equal to or smaller than the enzyme limit loading and result in surface adsorption, whereas excessively large pores increase the risk of enzyme leaching [79].

Laccase can be effectively encapsulated within vesicles such as liposomes and in matrices like sol–gels, which permit free diffusion of substrates and products while shielding the enzyme from deactivation [80]. For instance, Myceliophthora thermophila laccase encapsulated in a sol–gel matrix demonstrated improved pH and thermal stability, higher tolerance to inhibitors, and long-term activity retention despite a slight reduction in substrate affinity [81]. Encapsulation also enables precise control over the thickness of the immobilized enzyme layer and allows the incorporation of diverse materials to enhance performance [82]. Various encapsulation supports offer distinct advantages: nanocellulose provides a renewable and biocompatible platform, thin silicate films deliver mechanical robustness and regulated permeability, and graphene oxide–laccase nanoassemblies improve electron transfer and catalytic efficiency. Similarly, self-assembled monolayers of 3-mercaptopropionic acid allow optimal enzyme orientation, while sol–gel systems form a porous protective network that enhances enzyme stability and supports efficient substrate access. These versatile approaches make encapsulation one of the most promising strategies for stabilizing laccase and extending its use in industrial and environmental biocatalysis.

5.1.4. Cross-Linked Enzyme Aggregates (CLEAs)

CLEAs are formed by precipitating the enzyme and cross-linking the aggregates by using bifunctional agents like (GA) [83]. This method avoids carriers, making it cost-effective and yielding highly concentrated catalytic units. CLEAs of laccase have been reported to offer excellent thermal and operational stability, with more than 80% activity retained after multiple reuse cycles and over 90% decolorization efficiency for dyes such as malachite green and methyl red, confirming the potential of CLEAs as effective carrier-free biocatalysts [84]. CLEAs have been applied in fluidized-bed reactors to remove EDCs such as nonylphenol, bisphenol A, and triclosan at concentrations up to 5 mg/L [85]. The extensive cross-linking on the enzyme surface enhances structural rigidity, preventing thermal unfolding of laccase and resulting in excellent thermal stability. This stabilization enables efficient and complete removal of EDCs under operational conditions. CLEAs of T. versicolor laccase exhibited remarkable storage stability, retaining 80% of their initial activity after 70 days at 4 °C. Moreover, these CLEAs achieved up to 95% decolorization efficiency for synthetic dyes such as malachite green, bromothymol blue, and methyl red, highlighting their strong potential for long-term wastewater treatment applications [86].

5.2. Support Materials for Immobilization

Key factors of support selection, including surface area, porosity, biocompatibility, mechanical strength, and cost-effectiveness play crucial role in the success of laccase immobilization [87]. Natural polymers such as Chitosan, alginate, cellulose are biodegradable and non-toxic, whereas inorganic materials, including silica, clay, and zeolites, provide high mechanical strength and thermal stability [88,89]. Magnetic nanoparticles allow easy recovery of enzyme using a magnetic field [90]. On the other side, carbon-based materials, including biochar, graphene oxide had high surface area and adsorption capacity [91]. The choice of support material plays a pivotal role in the successful immobilization of laccase, directly impacting enzyme stability, activity, and reusability. Ideal supports must offer high surface area, mechanical strength, chemical stability, and compatibility with the enzyme’s functional groups to maximize catalytic efficiency [87]. Supports can be broadly classified into organic polymers, inorganic materials, hybrid composites, and nanostructured carriers [82].

Organic supports such as chitosan, alginate, cellulose, and synthetic polymers (e.g., polyacrylamide) are widely used due to their biocompatibility and mild immobilization conditions [82]. Chitosan, with abundant amino and hydroxyl groups, enables covalent bonding or cross-linking with agents like GA, improving enzyme loading and resistance to metal ion inhibitors [92]. Chitosan composites with bentonite clay or magnetic nanoparticles enhance surface area and facilitate easy recovery. Similarly, cellulose and its derivatives provide a hydrophilic, biodegradable matrix that supports high enzyme retention and are frequently modified to introduce functional groups for stronger attachment.

Inorganic supports such as silica, zeolites, and metal oxides (ZnO, MnO₂, TiO₂) offer exceptional mechanical strength, high porosity, and thermal stability [82]. Functionalization with amino, epoxy, or carboxyl groups enables covalent immobilization of laccase, reducing enzyme leaching and improving operational stability. Silica nanoparticles and mesoporous silica are particularly attractive for large-scale applications because they allow precise control of pore size, enhancing enzyme accessibility and preventing diffusional limitations [93].

Nanostructured and carbon-based materials (graphene oxide, carbon nanotubes, biochar) have gained prominence due to their high surface area and superior conductivity, making them ideal for bioelectrochemical applications [94]. Functionalization with carboxyl or amino groups followed by cross-linking with GA or N-Ethyl-N’-(3-dimethylaminopropyl) carbodiimide/N-hydroxysuccinimide (EDC/NHS) chemistry results in oriented immobilization, leading to higher catalytic turnover and stability. Multi-walled carbon nanotubes treated with nitric acid and subsequently activated with EDC/NHS have shown improved thermal stability and immobilization yield compared to non-functionalized forms [95].

Hybrid supports and composite systems integrate the strengths of multiple materials. For example, silica–chitosan composites improve biocompatibility, mechanical durability, and reusability [96]. Incorporation of magnetic components into supports enables magnetic recovery, crucial for continuous-flow operations. To minimize activity loss during immobilization, spacer arms such as β-alanine and polyethyleneimine are often used to orient the enzyme away from the support surface, reducing steric hindrance and preserving the accessibility of the active site [82]. Oriented immobilization through carbohydrate moieties has been reported to provide higher catalytic activity compared to random attachment through amino groups. Overall, the rational selection and functionalization of support materials is key to optimizing laccase performance for environmental applications. Future directions involve the development of nanocomposites with tailored pore architectures, greener cross-linking chemistries (e.g., genipin), and multifunctional hybrid carriers that combine adsorption, catalytic degradation, and facile recovery for scalable wastewater treatment and bioremediation processes.

5.3. Stability Enhancement Strategies

Beyond immobilization, additional strategies are employed to further enhance the functional stability of laccase under environmental and industrial conditions. Additives like polyethylene glycol (PEG), glycerol, and calcium ions can help stabilize laccase structure by maintaining hydration and reducing aggregation [97]. Co-solvents such as ionic liquids and deep eutectic solvents have also shown promise in preserving enzyme activity during storage and reaction. PEG-400 improved laccase activity and prevented denaturation during prolonged dye degradation runs [98].

Genetic engineering has been employed to design mutant laccases with enhanced thermal stability, pH tolerance, and resistance to inhibitors. Directed evolution enables the creation of enzyme variant libraries, allowing selection of the most effective candidates. A genetically engineered variant of T. laccase exhibited 2-fold higher thermal stability and broader pH tolerance compared to wild-type [99]. Fusing laccase genes with stabilizing protein domains or tags such as cellulose-binding modules (CBMs) improves its binding to cellulose-based carriers and protects against proteolysis and denaturation [100]. Fusion of laccase with CBMs enhanced its binding to cellulose beads and improved reusability in a flow-through bioreactor [101]. The integration of nanomaterials has revolutionized laccase stability improvement [102]. Nano-supports offer large surface area, functional groups for binding, and unique physicochemical properties. Examples include laccase immobilized on graphene oxide or carbon nanotubes, hybrid materials like laccase–nanofiber composites, and Nanozymes (nanoparticles with enzyme-like properties) supporting laccase for synergistic effects [103,104].

5.4. Advantages of Immobilized Laccase in Environmental Applications

Immobilized laccase shows multiple advantages in environmental remediation that use reusability, operational stability, scalability and the ease of separation [105]. While immobilization offers several benefits, it may also introduce limitations such as diffusional limitations, initial high cost of supports or chemicals and potential alteration of enzyme active sites during binding [106]. Future research is expected to focus on the development of low-cost, eco-friendly support materials from agro-industrial waste. It also focuses on the smart carriers responsive to stimuli (e.g., pH, temperature, or magnetic fields). Furthermore, co-immobilization of laccase with other enzymes (e.g., peroxidase) can also be considered for synergistic degradation. Advanced computational tools for rational design of immobilization strategies can also be employed.

6. Integration with Green Technologies

The increasing need for sustainable, eco-friendly, and cost-effective solutions to pollution has led to the integration of laccase-based systems with various green technologies. Laccase’s broad substrate range, ability to operate under mild conditions, and compatibility with renewable resources make it an ideal partner for emerging environmentally conscious processes. Combining laccase with green technologies enhances pollutant degradation efficiency, expands the scope of treatable contaminants, and reduces energy consumption and secondary waste generation.

6.1. Coupling with Advanced Oxidation Processes (AOPs)

Advanced Oxidation Processes (AOPs), including ozonation, photocatalysis, Fenton’s reaction, and electrochemical oxidation, generate highly reactive radicals such as hydroxyl radicals capable of degrading persistent organic pollutants [107]. Although highly effective, AOPs alone can be costly and energy-intensive, limiting their large-scale application. Integration of laccase with AOPs provides a synergistic solution; for example, laccase first oxidizes recalcitrant compounds into more biodegradable intermediates, which are subsequently mineralized more efficiently by AOPs [108]. In return, AOPs can target pollutants resistant to enzymatic degradation, resulting in broader pollutant removal. For example, coupling laccase with UV/TiO₂ photocatalysis achieved the removal of pharmaceuticals from wastewater, demonstrating the promise of hybrid enzymatic-AOP systems for sustainable wastewater treatment [109]. In this context, AOPs such as ozonation, UV/H₂O₂ treatment, and photocatalysis are better described as enabling technologies rather than inherently ‘green’ solutions. While they are energy- and reagent-intensive, their integration with laccase-based systems can significantly reduce the chemical and energy input required by each process alone. For example, laccase pretreatment can partially oxidize persistent pollutants, lowering the AOP dose required for complete mineralization, thereby reducing overall chemical consumption and secondary by-product formation [110]. Similarly, combining AOPs with enzymatic steps enables shorter treatment times and improved degradation efficiency, which enhances process sustainability.

6.2. Integration with Nanotechnology

Nanotechnology has emerged as a powerful tool to enhance the performance of laccase in environmental applications, particularly through improved immobilization, stability, and catalytic efficiency [5]. Various nanomaterials, including graphene oxide (GO), magnetic nanoparticles (MNPs), carbon nanotubes, and metal–organic frameworks (MOFs), have been employed to optimize enzyme performance. MNPs enable the easy recovery and reuse of laccase using a simple magnetic field, thereby lowering operational costs [111]. GO provides a high surface area and numerous functional groups that facilitate both covalent and non-covalent enzyme attachment, improving electron transfer and catalytic activity. Similarly, MOFs combine adjustable pore dimensions with high enzyme-loading potential, effectively safeguarding laccase against denaturation and prolonging operational stability for practical applications [44]. A notable example is the immobilization of laccase on GO-MNP hybrid supports, which retained its activity and demonstrated improved tolerance to pH fluctuations, highlighting the potential of nanomaterial-assisted systems for sustainable pollutant remediation [112].

6.3. Bioelectrochemical Systems (BES)

Bioelectrochemical systems, including microbial fuel cells (MFCs) and enzymatic biofuel cells, harness biological catalysts to drive redox reactions and generate electricity in a sustainable manner. Within these systems, laccase is widely applied as an oxygen-reducing biocathode catalyst, offering an eco-friendly alternative to expensive and toxic metal catalysts [113]. Laccase, when immobilized with CaCO₃ microspheres, maintains higher long-term activity and prevents anode acidification. It also significantly boosts electricity generation while enabling efficient degradation of PAHs such as phenanthrene and pyrene, and reshapes microbial communities to support cleaner soil environments [114]. Laccase from T. versicolor adsorbed to carbon nanotube electrodes with a mean residence time of 2 days and a half-life of 9 days at pH 5, extended cathode lifetime 2.5-fold, highlighting laccase’s potential for durable, self-regenerating biofuel cells [115]. This integrated approach supports the circular bioeconomy by transforming waste streams into valuable energy resources while purifying water. For instance, Immobilization of laccase in microbial fuel cell biocathodes enhanced enzyme stability, reusability, and power output as compared to free enzyme, with polyaniline-crosslinked laccase showing the best activity retention (81%) and highest power density (38 ± 1.7 mW m⁻²), while still supporting effective dye decolourization [116].

6.4. Integration with Membrane Filtration Systems

Membrane technologies such as ultrafiltration and nanofiltration are widely used for removing suspended solids and dissolved contaminants [117]. However, their efficiency is often hindered by fouling, which shortens membrane lifespan and increases operational costs. Incorporating laccase into these systems, either by embedding or coating membranes, provides a promising solution to overcome this limitation. Laccase can degrade organic foulants in situ, reducing fouling and maintaining higher flux rates, while simultaneously enabling the continuous breakdown of micropollutants during filtration [118]. A multilayer laccase-based biocatalytic membrane incorporating UiO-66-NH₂ nanoparticles achieved efficient micropollutant removal, eliminating >96% bisphenol A and >98% dyes with high water permeance, broad pH tolerance, good reusability, and stable activity for over 10 days [119].

6.5. Co-Immobilization with Other Enzymes

Certain pollutants are highly recalcitrant and cannot be effectively degraded by laccase alone. To address this challenge, laccase can be co-immobilized with complementary enzymes such as peroxidases, cellulases, or lipases, or integrated into microbial consortia to create multifunctional systems with broader catalytic capabilities [120,121]. These synergistic setups enable the simultaneous breakdown of complex pollutant mixtures, including lignin derivatives, dyes, and other industrial contaminants, which would otherwise persist in the environment. Immobilized and co-immobilized laccase with versatile peroxidase on magnetic silica microspheres effectively depolymerized lignin from Casuarina equisetifolia [122].

6.6. Integration with Renewable Energy Systems

Laccase-driven processes can be further enhanced by coupling them with renewable energy sources, thereby minimizing reliance on fossil fuels and reducing carbon footprints. Laccase activity was boosted by SDDAB, NaCl, and NIR irradiation, yielding a 29.2% increase in specific activity and enabling the green synthesis of high-performance, UV-resistant and photothermal coatings [123]. Similarly, wind-powered aeration can supply the necessary oxygen for laccase activity without additional energy input. These integrated approaches not only improve the efficiency of enzymatic treatments but also align with sustainable energy goals. A laccase–methylene blue (LAC-MB) photo-enzyme system significantly enhanced electron transfer to T1 Cu, boosting guaiacol degradation from 28.8% to 91.46% under red-LED light, enabling efficient phenolic and non-phenolic lignin depolymerization and offering a promising route for high-efficiency lignocellulosic biomass processing [124].

6.7. Role in Circular Bioeconomy Models

Within a circular economy framework, waste is viewed as a resource rather than a burden, and laccase plays a pivotal role in enabling this transition. By catalyzing the breakdown of lignin in lignocellulosic biomass, laccase facilitates the production of bio-based chemicals, fuels, and other sustainable materials [125]. It also aids in the detoxification of industrial residues, allowing their safe reuse in agricultural or industrial applications without causing environmental harm. Furthermore, laccase contributes to the valorization of agro-industrial waste streams by transforming them into high-value products such as compost, biochar, or bioplastics. These applications not only reduce environmental pollution but also support resource recovery and sustainable development goals.

Although integrating laccase with green technologies offers significant benefits, several challenges must be addressed for successful large-scale application. Enzyme stability remains a key limitation, as maintaining long-term catalytic activity under industrial conditions is essential for cost-effectiveness. Similarly, scale-up feasibility is critical, since many promising lab-scale demonstrations have yet to be translated into effective, economically viable industrial systems. Another concern is mediator toxicity, as reliance on synthetic mediators conflicts with sustainability goals, underscoring the need for safer, plant-derived alternatives. Looking ahead, research should prioritize the development of smart hybrid systems, such as self-regenerating laccase–nanocomposites or bioreactors, which can enhance efficiency, prolong durability, and ensure environmental safety, thereby advancing laccase-based technologies toward practical, sustainable deployment.

Even though laccase has shown great promise in laboratory studies, moving it from experimental setups to real-world environmental cleanup systems is not straightforward. Translational challenges arise when the conditions in actual wastewater plants, contaminated soils, or industrial processes differ greatly from controlled lab environments. In many advanced research trials, laccase works well on single pollutants under ideal conditions. However, real environmental samples are complex mixtures containing dyes, pharmaceuticals, pesticides, oils, and heavy metals. These compounds may compete for the enzyme’s active site or even block it completely. Some industrial waste streams also contain solvents or detergents that partially deactivate the enzyme. Recent studies have reported significant progress in the development of laccase-based biocatalysts, including enhanced immobilization techniques, hybrid systems with nanomaterials, and their integration into continuous bioreactors for wastewater treatment [8].

7. Translational Pathways of Laccase

Translating the laboratory success of laccase-based systems into real-world environmental applications involves multiple interconnected steps, each with its own scientific, technical, and regulatory challenges (Figure 4). Figure 4 captures these critical stages, highlighting the need to move beyond controlled experiments and address the complexities of field implementation.

7.1. From Laboratory Success to Real Waste Streams

Laccase research has achieved significant breakthroughs under laboratory conditions, where variables such as pH, temperature, and pollutant concentration can be precisely optimized. However, performance in real waste streams is often less predictable due to the presence of multiple contaminants, fluctuating operating conditions, and potential enzyme inhibitors such as heavy metals or surfactants. Demonstrating reproducible performance in these complex matrices is the first major step in the translational journey.

7.2. Ensuring Long-Term Stability and Reuse

For laccase-based systems to be economically viable, they must retain their activity over extended operational periods. Figure 4 underscores the importance of long-term stability and reuse, which can be achieved through immobilization techniques, nanocarrier support systems, and protein engineering to enhance thermal and pH stability. Reusability reduces the overall cost of treatment and minimizes the frequency of enzyme replenishment, a key factor for large-scale deployment.

7.3. Addressing the Cost–Benefit Gap

Even with improved stability, the cost–benefit gap must be addressed. Production costs of purified laccase, expenses associated with immobilization, and infrastructure for bioreactor deployment need to be justified against conventional treatment methods. Using inexpensive agro-industrial residues as fermentation substrates, developing mediator-free systems, and designing scalable bioreactors can help bridge this economic gap.

7.4. Overcoming Limited Action Without Helpers

Laccase alone has a limited substrate range, particularly for non-phenolic compounds. The pathway highlights the need to overcome limited action without helpers, which can be achieved by incorporating redox mediators, coupling with other oxidative enzymes (e.g., peroxidases), or integrating with AOPs. These hybrid systems improve pollutant coverage and ensure near-complete detoxification of complex mixtures.

7.5. Scaling from Lab to Field

Successful laboratory systems must undergo scale-up trials in pilot plants or semi-field reactors before full industrial implementation. Scaling introduces additional challenges, including mass transfer limitations, enzyme distribution within treatment units, and maintaining catalytic efficiency at larger volumes. Computational modelling and continuous-flow bioreactor designs are useful tools in overcoming these barriers.

7.6. Regulatory and Acceptance Barriers

Even technically sound solutions must pass through regulatory approval and public acceptance. Authorities require proof of safety, by-product analysis, and compliance with environmental standards. Additionally, industries must be convinced of the technology’s reliability and cost-effectiveness to adopt it on a commercial scale.

7.7. Field Application and Future Integration

Finally, achieving field application completes the translational pathway. This stage involves real-time monitoring, adaptive process control, and integration with existing treatment infrastructure. Coupling laccase systems with renewable energy sources (e.g., solar-powered bioreactors) and implementing continuous monitoring biosensors can further enhance the sustainability and acceptance of this technology.

8. Conclusions

Laccase has emerged as a cornerstone of eco-friendly remediation technologies, offering a sustainable alternative to conventional physicochemical treatments. Its unique multi-copper active site enables the oxidation of a wide range of phenolic, non-phenolic, and xenobiotic compounds while reducing oxygen to water, thus avoiding secondary pollution. This versatility has allowed laccase to be successfully applied to wastewater treatment, soil and air bioremediation, detoxification of agro-industrial residues, and even biosensor development for real-time environmental monitoring. Breakthroughs in enzyme immobilization, nanotechnology-assisted stabilization, and bioreactor engineering have addressed key challenges such as low operational stability and high production costs, enabling scalable deployment. Moreover, laccase’s compatibility with circular bioeconomy models highlights its potential to transform waste streams into value-added products such as bio-based polymers, compost, and biofuels. Real-world waste streams are often complex, containing mixtures of dyes, pesticides, pharmaceuticals, heavy metals, and surfactants that may inhibit enzymatic activity. Continued research on engineering laccase variants with enhanced stability, broader substrate range, and tolerance to inhibitory compounds is critical. Overall, laccase represents not merely a pollutant-degrading enzyme but a strategic tool for advancing sustainable, low-carbon environmental technologies.

9. Future Directions in Laccase-Based Remediation

Laccase research has entered an exciting phase where innovations in biotechnology, materials science, and systems engineering are converging to enable its transition from laboratory-scale success to scalable, real-world applications. Figure 5 outlines four key strategic areas that will shape the future of laccase-based remediation, including advanced nanomaterials, metabolic engineering, scalable production, and hybrid systems. Together, these directions provide a roadmap for enhancing the efficiency, stability, and economic feasibility of laccase technologies.

9.1. Advanced Nanomaterials

Nanotechnology offers significant opportunities for improving laccase performance. Nano-based carriers, such as magnetic nanoparticles, carbon nanotubes, and metal–organic frameworks, can immobilize laccase, providing high surface area, improved catalytic efficiency, and easy recovery for reuse. Nanostructured enzyme mimics (nanozymes) with laccase-like activity are also emerging as robust, cost-effective alternatives, especially for harsh industrial conditions. Additionally, the design of eco-friendly nanomaterials biodegradable, non-toxic, and recyclable will be crucial for ensuring that the remediation process itself does not contribute to secondary pollution.

9.2. Metabolic Engineering

Metabolic and protein engineering are powerful tools for producing laccase variants with enhanced expression levels, improved thermostability, and wider pH optima. Engineering host strains such as E. coli, Pichia pastoris, or filamentous fungi can increase production yields, while directed evolution and rational design can tailor redox potential or expand substrate specificity. Host strain optimization can also reduce production costs, making industrial-scale enzyme supply more economically viable.

9.3. Scalable Production

For laccase to become a mainstream biocatalyst, cost-effective production methods are essential. Future research will likely emphasize the use of low-cost fermentation substrates, such as agro-industrial residues, and optimized bioprocessing strategies that maximize yield while minimizing downstream purification costs. Advances in immobilization techniques, including co-immobilization with synergistic enzymes or integration into continuous-flow bioreactors will further improve operational stability and allow repeated use, which is critical for economic feasibility in large-scale treatment plants.

9.4. Hybrid Systems

Perhaps the most promising direction is the development of hybrid remediation systems that combine laccase with complementary catalytic approaches. Nanomaterial–enzyme composites can influence the catalytic activity of laccase with the adsorption capacity of the carrier, improving pollutant removal efficiency. Integration with other catalysts, such as peroxidases, photocatalysts, or electrochemical systems, can overcome the limitations of laccase alone, enabling degradation of recalcitrant pollutants like PFAS or halogenated aromatics. Future designs may include synergistic remediation processes that combine enzymatic pre-treatment with advanced oxidation processes, reducing energy consumption while achieving near-complete mineralization of contaminants.

The convergence of these four strategic areas will accelerate the translation of laccase technologies from bench to field, enabling scalable, cost-effective, and sustainable solutions for wastewater, soil, and air decontamination. The future lies in creating integrated, smart systems responsive to environmental conditions, powered by renewable energy, and capable of real-time monitoring through biosensor feedback. These efforts will position laccase not just as an academic curiosity but as a cornerstone of the next generation of green technologies supporting a circular and low-carbon economy.