Biodegradation of polycyclic aromatic hydrocarbons (PAHs) by laccase from Trametes versicolor covalently immobilized on amino-functionalized SBA-15

Mechanism of non-phenolic substrate oxidation by the fungal laccase Type 1 copper site from Trametes versicolor: the case of benzo[a]pyrene and anthracene

Laccases (EC 1.10.3.2) are multicopper oxidases with the capability to oxidize diverse phenolic and non-phenolic substrates. While the molecular mechanism of their activity towards phenolic substrates is well-established, their reactivity towards non-phenolic substrates, such as polycyclic aromatic hydrocarbons (PAHs), remains unclear. To elucidate the oxidation mechanism of PAHs, particularly the activation mechanism of the sp2 aromatic C-H bond, we conducted a density functional theory investigation on the oxidation of two PAHs (anthracene and benzo[a]pyrene) using an extensive model of the T1 copper catalytic site of the fungal laccase from Trametes versicolor.

Construction of Immobilized Laccase System Based on ZnO and Degradation of Mesotrione

Mesotrione (MES) is a new environmental pollutant. Some reports have indicated that microbial enzymes could be utilized for MES degradation. Laccase is a green biocatalyst whose potential use in environmental pollutant detoxification has been considered limited due to its poor stability and reusability. However, these issues may be addressed using enzyme immobilization. In the present study, we sought to optimize conditions for laccase immobilization, to analyze and characterize the characteristics of the immobilized laccase, and to compare its enzymatic properties to those of free laccase. In addition, we studied the ability of laccase to degrade MES, and analyzed the metabolic pathway of MES degradation by immobilized laccase. The results demonstrated that granular zinc oxide material (G-ZnO) was successfully used as the carrier for immobilization. G-ZnO@Lac demonstrated the highest recovery of enzyme activity and exhibited significantly improved stability compared with free laccase. Storage stability was also significantly improved, with the relative enzyme activity of G-ZnO@Lac remaining at about 54% after 28 days of storage (compared with only 12% for free laccase). The optimal conditions for the degradation of MES by G-ZnO@Lac were found to be 10 mg, 6 h, 30 °C, and pH 4; under these conditions, a degradation rate of 73.25% was attained. The findings of this study provide a theoretical reference for the laccase treatment of 4-hy-droxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicide contamination.

Laccase as a useful assistant for maize to accelerate the phenanthrene degradation in soil

Polycyclic aromatic hydrocarbon (PAH) pollution has attracted much attention due to their wide distribution in soil environment and serious harm to human health. In order to establish an efficient and eco-friendly technology for remediation of PAH-contaminated soil, phytoremediation utilizing maize assisted with enzyme remediation was explored in this study. The results showed that the participation of laccase could promote the degradation of phenanthrene (PHE) from soil and significantly reduce the accumulation of PHE in maize. The degradation efficiency of PHE in soil could reach 77.19% under laccase-assisted maize remediation treatment, while the accumulation of PHE in maize roots and leaves decreased by 41.23% and 74.63%, respectively, compared to that without laccase treatment, after 24 days of maize cultivation. Moreover, it was found that laccase addition shifted the soil microbial community structure and promoted the relative abundance of some PAH degrading bacteria, such as Pseudomonas and Sphingomonas. In addition, the activities of some enzymes that were involved in PAH degradation process and soil nutrient cycle increased with the treatment of laccase enzyme. Above all, the addition of laccase could not only improve the removal efficiency of PHE in soil, but also alter the soil environment and reduce the accumulation of PHE in maize. This study provided new perspective for exploring the efficiency of the laccase-assisted maize in the remediation of contaminated soil, evaluating the way for reducing the risk of secondary pollution of plants in the phytoremediation process.

Laccase immobilized on nanocomposites for wastewater pollutants degradation: current status and future prospects

The bio-enzyme degradation technology is a promising approach to sustainably remove pollution in the water and laccase is one of the most widely used enzymes in this area. Nevertheless, the further industrial application of laccase is limited by low stability, short service, low reusability and high price. The immobilization technology can significantly improve the stability and reusability of enzymes and thus promoting their industrial applications. Nanocomposite materials have been developed and applied in the efficient immobilization of laccase due to their superior physical, chemical, and biological performance. This paper presents a comprehensive review of various nanocomposite immobilization methods for laccase and the consequent changes in enzymatic properties post-immobilization. Additionally, a comprehensive analysis is conducted on the factors that impact laccase immobilization and its water removal efficiency. Furthermore, this review examines the effectiveness of common contaminants' removal mechanisms while summarizing and discussing issues related to laccase immobilization on nanocomposite carriers. This review aims to provide valuable guidance for enhancing laccase immobilization efficiency and enzymatic water pollutant removal.

Removal of pentachlorophenol and phenanthrene from lignocellulosic biorefinery wastewater by a biocatalytic/biosurfactant system comprising cross-linked laccase aggregates and rhamnolipid

Synthesis and characterization of highly active cross-linked laccase aggregates (CLLAs) were performed and evaluated for removal of pentachlorophenol and phenanthrene from lignocellulosic biorefinery wastewater. Laccase from Tramates versicolor MTCC 138 was insolubilized as CLLAs via precipitation with 70% ammonium sulphate and simultaneous cross-linking with 5 mM glutaraldehyde to obtain activity recovery of 89.1%. Compared to the free laccase, the pH and thermal stability of the prepared CLLAs were significantly higher. At a high temperature of 60 °C, free laccase had a half-life of 0.25 h, while CLLAs had a half-life of 6.2 h. In biorefinery wastewater (pH 7.0), the free and CLLAs were stored for 3 day at a temperature of 30 °C. Free laccase completely lost their initial activity after 60 h; however, the CLLAs retained 39% activity till 72 h. Due to its excellent stability, free laccase and CLLAs were assessed for removing pentachlorophenol and phenanthrene in wastewater. CLLAs could remove 51-58% of pentachlorophenol (PCP) and phenanthrene (PHE) in 24 h. Biosurfactants, including surfactin, sophorolipid, and rhamnolipid, were assessed for their aptitude to improve the removal of organic contaminants in wastewater. Biorefinery wastewater incubated with all surfactants enhanced PCP and PHE removal compared to the no-surfactant controls. Further, 1 μM rhamnolipid significantly amplified pentachlorophenol and phenanthrene removal to 81-93% for free laccase and CLLAs, respectively.

Molecular advances in mycoremediation of polycyclic aromatic hydrocarbons: Exploring fungal bacterial interactions

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous high global concern environmental pollutants and tend to bioaccumulate due to hydrophobic properties. These xenobiotics, having variable concentrations along different matrices, gradually undergo various physical, chemical, and biological transformation processes. Myco-remediation aids accelerated degradation by effectively transforming complex ring structures to oxidized/hydroxylated intermediates, which can further funnel to bacterial degradation pathways. Exploitation of such complementing fungal-bacterial enzymatic activity can overcome certain limitations of incomplete bioremediation process. Furthermore, high-throughput molecular methods can be employed to unveil community structure, taxon abundance, coexisting community interactions, and metabolic pathways under stressed conditions. The present review critically discusses the role of different fungal phyla in PAHs biotransformation and application of fungal-bacterial cocultures for enhanced mineralization. Moreover, recent advances in bioassays for PAH residue detection, monitoring, developing xenobiotics stress-tolerant strains, and application of fungal catabolic enzymes are highlighted. Application of next-generation sequencing methods to reveal complex ecological networks based on microbial community interactions and data analysis bias in performing such studies is further discussed in detail. Conclusively, the review underscores the application of mixed-culture approach by critically highlighting in situ fungal-bacterial community nexus and its role in complete mineralization of PAHs for the management of contaminated sites.

Co-immobilization of electron mediator and laccase onto dialdehyde starch cross-linked magnetic chitosan nanomaterials for organic pollutants’ removal

In this study, an amino-functionalized ionic liquid-modified magnetic chitosan (MACS-NIL) containing 2,2-diamine-di-3-ethylbenzothiazolin-6-sulfonic acid (ABTS) was used as a carrier, and dialdehyde starch (DAS) was used as a cross-linking agent to covalently immobilize laccase (MACS-NIL-DAS-lac), which realized the co-immobilization of laccase and ABTS. The carrier was characterized by Fourier infrared transform spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction analysis, electron paramagnetic resonance, etc. The immobilization efficiency and activity retention of MACS-NIL-DAS-lac could reach 76.7% and 69.8%, respectively. At the same time, its pH stability, thermal stability, and storage stability had been significantly improved. In the organic pollutant removal performance test, the removal rate of 2,4-dichlorophenol (10 mg/L) by MACS-NIL-DAS-lac (1 U) could reach 100% within 6 h, and the removal efficiency could still reach 88.6% after six catalytic runs. In addition, MACS-NIL-DAS-lac also showed excellent degradation ability for other conventional phenolic pollutants and polycyclic aromatic hydrocarbons. The research results showed that MACS-NIL-DAS fabricated by the combination inorganic material, organic biomacromolecules, ionic liquid, and electron mediator could be used as a novel carrier for laccase immobilization and the immobilized laccase showed excellent removal efficiency for organic pollutants.

Laccase-assisted degradation of emerging recalcitrant compounds - A review

The main objective of this review is to provide up to date, brief, irrefutable, organized data on the conducted experiments on a range of emerging recalcitrant compounds such as Diclofenac (DCF), Chlorophenols (CPs), tetracycline (TCs), Triclosan (TCS), Bisphenol A (BPA) and Carbamazepine (CBZ). These compounds were selected from the categories of pharmaceutical contaminants (PCs), endocrine disruptors (EDs) and personal care products (PCPs) on the basis of their toxicity and concentration retained in the environment. In this context, detailed mechanism of laccase mediated degradation has been conversed that laccase assisted degradation occurs by one electron oxidation involving redox potential as underlying element of the process. Further, converging towards biotechnology, laccase immobilization increased removal efficiency, storage and reusability through various experimentally conducted studies. Laccase is being considered noteworthy as mediators facilitate laccase in oxidation of non-phenolic compounds and thereby increasing its substrate range which is being discussed in further in the review. The laccase assisted degradation mechanism of each compound has been elucidated but further studies to undercover proper degradation mechanisms needs to be performed.

Synthetic Saccharomyces cerevisiae tolerate and degrade highly pollutant complex hydrocarbon mixture

Fungal laccase (Lac) has become a very useful biocatalyst in different industries, bio-refineries and, most importantly, bioremediation. Many reports have also linked hydrocarbon tolerance and degradation by various microorganisms with Lac secretion. In this study, Trametes trogii Lac (Ttlcc1) was engineered into Saccharomyces cerevisiae strain CEN.PK2-1 C under the constitutive GPD promoter (pGPD) for multi-fold synthesis with efficient hydrocarbon tolerance and degradation. Protein expression in heterologous hosts is strictly strain-specific, it can also be influenced by the synthetic design and culture conditions. We compared synthetic designs with different shuttle vectors for the yeast strains and investigated the best culture conditions by varying the pH, temperature, carbon, nitrogen sources, and CuSO₄ amount. Two S. cerevisiae strains were built in this study: byMM935 and byMM938. They carry the transcription unit pGPD-Ttlcc1-CYC1t either inside the pRSII406 integrative plasmid (byMM935) or the pRSII426 multicopy plasmid (byMM938). The performance of these two synthetic strains were studied by comparing them to the wild-type strain (byMM584). Both byMM935 and byMM938 showed significant response to different carbon sources (glucose, galactose, lactose, maltose, and sucrose), nitrogen sources (NH₄Cl, NH₄NO₃, KNO₃, malt extract, peptone, and yeast extract), and solid state fermentation of different plant biomasses (bagasse, banana peels, corn cob, mandarin peels, and peanut shells). They performed best in optimized growth conditions with specific carbon and nitrogen sources, and a preferred pH in the range 3.5-4.5, temperature between 30 and 40 ⁰C, and 1 mM CuSO_4. In optimized yeast-growth medium, strain byMM935 showed the highest laccase activities of 1.621 ± 0.063 U/mL at 64 h, whereas byMM938 gave its highest activity (1.417 ± 0.055 U/mL) at 48 h. In this work, we established, by using Bushnell Hass synthetic medium, that the new Ttlcc1-yeast strains tolerated extreme pH and complex hydrocarbon mixture (CHM) toxicity. They degraded 60-90% of the key components in CHM within 48 h, including poly-cyclic aromatic hydrocarbons, alkyl indenes, alkyl tetralines, alkyl benzenes, alkyl biphenyls, and BTEX (Benzene, Toluene, Ethylbenzene, and Xylenes). This is the first report on the hydrocarbon degradation potential of a Ttlcc1-yeast. Compared to the native organism, such synthetic strains are better suited for meeting growing demands and have potentials for application in large-scale in situ bioremediation of hydrocarbon-polluted sites.

Effects of Adding Laccase to Bacterial Consortia Degrading Heavy Oil

High-efficiency bioremediation technology for heavy oil pollution has been a popular research topic in recent years. Laccase is very promising for the remediation of heavy oil pollution because it can not only convert bio-refractory hydrocarbons into less toxic or completely harmless compounds, but also accelerate the biodegradation efficiency of heavy oil. However, there are few reports on the use of laccase to enhance the biodegradation of heavy oil. In this study, we investigated the effect of laccase on the bacterial consortia degradation of heavy oil. The degradation efficiencies of bacterial consortia and the laccase-bacterial consortia were 60.6 ± 0.1% and 68.2 ± 0.6%, respectively, and the corresponding heavy oil degradation rate constants were 0.112 day−1 and 0.198 day−1, respectively. The addition of laccase increased the heavy oil biodegradation efficiency (p < 0.05) and biodegradation rate of the bacterial consortia. Moreover, gas chromatography–mass spectrometry analysis showed that the biodegradation efficiencies of the laccase-bacterial consortia for saturated hydrocarbons and aromatic hydrocarbons were 82.5 ± 0.7% and 76.2 ± 0.9%, respectively, which were 16.0 ± 0.3% and 13.0 ± 1.8% higher than those of the bacterial consortia, respectively. In addition, the degradation rate constants of the laccase-bacterial consortia for saturated hydrocarbons and aromatic hydrocarbons were 0.267 day−1 and 0.226 day−1, respectively, which were 1.07 and 1.15 times higher than those of the bacterial consortia, respectively. The degradation of C15 to C35 n-alkanes and 2 to 5-ring polycyclic aromatic hydrocarbons by laccase-bacterial consortia was higher than individual bacterial consortia. It is further seen that the addition of laccase significantly improved the biodegradation of long-chain n-alkanes of C22–C35 (p < 0.05). Overall, this study shows that the combination of laccase and bacterial consortia is an effective remediation technology for heavy oil pollution. Adding laccase can significantly improve the heavy oil biodegradation efficiency and biodegradation rate of the bacterial consortia.

Enzyme-assisted bioremediation approach for synthetic dyes and polycyclic aromatic hydrocarbons degradation

Environmental protection from emerging pollutants has become a significant challenge for mankind as an increasing number of contaminants, including synthetic dyes and polycyclic aromatic hydrocarbons (PAHs), represent a serious risk to ecological and environmental balance. Most synthetic dyes have complex aromatic structures and are resistant to degrade by classical approaches, such as physical and chemical processes, including adsorption, chemical coagulation, flocculation, ion exchange, membrane separation, froth flotation, and reverse osmosis. Enzymes-assisted catalytic transformation of pollutants has become a potential alternative to classical methods because of their ability to react with complex compounds, a quick degradation rate, and producing less harmful by-products. Plant peroxidases, and microbial laccase and lignin-degrading peroxidases (manganese and lignin peroxidase) have gained significant attention for treating aromatic waste due to their capability of oxidizing and detoxifying a wide range of recalcitrant xenobiotics, including PAHs and synthetic dyes. Peroxidases being efficient biocatalysts detoxify an array of toxic compounds by simple free-radical mechanism resulting in the formation of oxidized and depolymerized products of significantly reduced toxicity. Moreover, it is an ecofriendly and economically favorable approach towards the biodegradation of recalcitrant and toxic industrial waste. Among microbial and plant peroxidases, bacterial enzymes have broad substrate specificity and can transform a wide range of recalcitrant substrates. Ligninolytic enzymes oxidize the aromatic ring into quinones and acids by producing free hydroxyl radicals instead of dihydrodiols and mineralize aromatic hydrocarbon in combination with cytochrome P450, monooxygenases, and epoxide hydrolases. In the review, an attempt has been made to provide detailed knowledge about the availability of inexpensive peroxidases sources, their mechanism of action, and degradation potential. The present review summarizes the exploitation of peroxidases from plants, bacteria, and fungus (manganese peroxidase, lignin peroxidase, and laccases) for detoxification and degradation of textile dyes as well as PAHs. Conclusively, peroxidases have great potential to react with almost all classes of synthetic dyes and most PAHs due to broad substrate specificity and transformed them into less harmful metabolites.

A photobioreactor using Nannochloropsis oculata marine microalgae for removal of polycyclic aromatic hydrocarbons and sorption of metals in produced water

The objective of the present work is to evaluate the potential of the removal of PAHs and metal sorption for the treatment of petroleum produced water using a photobioreactor system with Nannochloropsis oculata microalgae. A set of photobioreactors with different gradients of produced water concentration diluted in saline water was designed, establishing five gradients (v/v): 0, 25, 50, 75 and 100%. These concentrations were established to test the removal of PAHs. The microalgal growth was monitored daily, noting the adaptation of microalgae to the addition of produced water as a culture medium, with cell growth of 5.24 × 10⁷ cells mL^-1 from 25% (v/v), 4.09 × 10⁷ cells mL^-1 from 50% (v/v), 2.77 × 10⁷ cells mL^-1 from 75% (v/v), and 1.17 × 10⁷ cells mL^-1 from 100%. The total removal efficiency of PAHs in the produced water was 94%. Organic compounds such as naphthalene, benzo(a)pyrene, benzo(b)fluoranthene, and acenaphthylene showed higher removal percentages, between 89 and 99% efficiency in produced water. Iron and zinc were the metals detected in the water produced, and iron reduced from 1.57 ± 0.08 mg L^-1 to <0.1 mg L^-1 after 28 days of cultivation, whereas zinc increased by 0.23 ± 0.05 to 3.90 ± 0.46 mg L^-1. The PAHs removal may have occurred in two ways, by intracellular bioaccumulation or biodegradation by oxidoreductase enzymes. 0.2 g of dry biomass with maximum extraction of oil obtained 3.07% and generation of 3.70% of protein was considered as value-added products for biodiesel and bioplastics.

Bioremoval and tolerance study of sulfamethoxazole using whole cell Trichoderma harzianum isolated from rotten tree bark

Antibiotic contamination raises concerns over antibiotic resistance genes (ARGs), which can severely impact the human health and environment. Sulfamethoxazole (SMX) is a widely used antibiotic that is incompletely metabolized in the body. In this study, the research objectives were (1) to isolate the native strain of Trichoderma sp. from the environment and analyze the tolerance toward SMX concentration by evaluating fungal growth, and (2) to investigate the potential of SMX removal by fungi. The potential fungi isolated from rotten tree bark showed 97% similarity to Trichoderma harzianum (Accession no. MH707098.1). The whole cell of fungi was examined in vitro; the strain Trichoderma harzianum BGP115 eliminated 71% of SMX after 7 days, while the white rot fungi Trametes versicolor, demonstrated 90% removal after 10 days. Furthermore, the tolerance of fungal growth toward SMX concentration at 10 mg L^-1 was analyzed, which indicated that Trichoderma harzianum BGP115 (the screened strain) exhibited more tolerance toward SMX than Trametes versicolor (the reference strain). The screened fungi isolated from rotted tree bark demonstrated the ability of SMX bioremoval and the potential to be tolerant to high concentrations of SMX.

A comprehensive insight into the application of white rot fungi and their lignocellulolytic enzymes in the removal of organic pollutants

Environmental problems resultant from organic pollutants are a major current challenge for modern societies. White rot fungi (WRF) are well known for their extensive organic compound degradation abilities. The unique oxidative and extracellular ligninolytic systems of WRF that exhibit low substrate specificity, enable them to display a considerable ability to transform or degrade different environmental contaminants. In recent decades, WRF and their ligninolytic enzymes have been widely applied in the removal of polycyclic aromatic hydrocarbons (PAHs), pharmaceutically active compounds (PhACs), endocrine disruptor compounds (EDCs), pesticides, synthetic dyes, and other environmental pollutants, wherein promising results have been achieved. This review focuses on advances in WRF-based bioremediation of organic pollutants over the last 10 years. We comprehensively document the application of WRF and their lignocellulolytic enzymes for removing organic pollutants. Moreover, potential problems and intriguing observations that are worthy of additional research attention are highlighted. Lastly, we discuss trends in WRF-remediation system development and avenues that should be considered to advance research in the field.

Recent progress in magnetic nanoparticles and mesoporous materials for enzyme immobilization: an update

Enzymes immobilized onto substrates with excellent selectivity and activity show a high stability and can withstand extreme experimental conditions, and their performance has been shown to be retained after repeated uses. Applications of immobilized enzymes in various fields benefit from their unique characteristics. Common methods, including adsorption, encapsulation, covalent attachment and crosslinking, and other emerging approaches (e.g., MOFs) of enzyme immobilization have been developed mostly in recent years. In accordance with these immobilization methods, the present review elaborates the application of magnetic separable nanoparticles and functionalized SBA-15 and MCM-41 mesoporous materials used in the immobilization of enzymes.

Recent environmental applications of and development prospects for immobilized laccase: a review

Laccases have enormous potential as promising 'green' biocatalysts in environmental applications including wastewater treatment and polluted soil bioremediation. The catalytic oxidation reaction they perform uses only molecular oxygen without other cofactors, and the only product after the reaction is water. The immobilization of laccase offers several improvements such as protected activity and enhanced stability over free laccase. In addition, the reusability of immobilized laccase is adistinct advantage for future applications. This review covers the sources of and progress in laccase research, and discusses the different methodologies of laccase immobilization that have emerged in the recent 5-10 years, as well as its applications to environmental fields, and evaluates these emerging technologies. Abbreviations: (2,4,6-TCP): 2,4,6-trichlorophenol; (2,4-DCP): 2,4-dichlorophenol; (ABTS), 2,2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid); (ACE), acetaminophen; (BC-AS), almond shell; (BC-PM), pig manure; (BC-PW), pine wood; (BPA), bisphenol A; (BPA), bisphenol A; (BPF), bisphenol F; (BPS), bisphenol S; (C₆₀), fullerene; (Ca-AIL), calcium-alginate immobilized laccase; (CBZ), carbamazepine; (CETY), cetirizine; (CHT-PGMA-PEI-Cu (II) NPs), Cu (II)-chelated chitosan nanoparticles; (CLEAs), cross-linked enzyme aggregates; (CMMC), carbon-based mesoporous magnetic composites; (COD), chemical oxygen demand; (CPH), ciprofloxacin hydrochloride; (CS), chitosan; (CTC), chlortetracycline; (Cu-AIL), copper-alginate immobilized laccase; (DBR K-4BL), Drimarene brilliant red K-4BL; (DCF), diclofenac; (E1),estrone; (E2), 17 β-estradiol; (EDC), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride; (EDCs), endocrine disrupting chemicals; (EE2), 17α-ethinylestradiol; (EFMs), electrospun fibrous membranes; (FL), free laccase; (fsMP), fumed silica microparticles; (GA-CBs), GLU-crosslinked chitosan beads; (GA-CBs), glutaraldehyde-crosslinked chitosan beads; (GA-Zr-MOF), graphene aerogel-zirconium-metal organic framework; (GLU), glutaraldehyde; (GO), graphene oxide; (HMCs), hollow mesoporous carbon spheres; (HPEI/PES), hyperbranched polyethyleneimine/polyether sulfone; (IC), indigo carmine; (IL), immobilized laccase; (k_cat), catalytic constant; (K_m), Michealis constant; (M-CLEAs), Magnetic cross-linked enzyme aggregates; (MMSNPs-CPTS-IDA-Cu²⁺), Cu²⁺-chelated magnetic mesoporous silica nanoparticles; (MSS), magnetic mesoporous silica spheres; (MWNTs), multi-walled carbon nanotubes; (MWNTs), multi-walled carbon nanotubes; (NHS), N-hydroxy succinimide; (O-MWNTs), oxidized-MWNTs; (P(AAm-NIPA)), poly(acrylamide-N-isopropylacrylamide); (p(GMA)), poly(glycidyl methacrylate); (p(HEMA)), poly(hydroxyethyl methacrylate); (p(HEMA-g-GMA)-NH₂, poly(glycidyl methacrylate) brush grafted poly(hydroxyethyl methacrylate); (PA6/CHIT), polyamide 6/chitosan; (PAC), powdered active carbon; (PAHs), polycyclic aromatic hydrocarbons; (PAM-CTS), chitosan grafted polyacrylamide hydrogel; (PAN/MMT/GO), polyacrylonitrile/montmorillonite/graphene oxide; (PAN/PVdF), polyacrylonitrile/polyvinylidene fluoride; (PEG), poly ethylene glycol; (PEI), Poly(ethyleneimine); (poly(4-VP)), poly(4-vinyl pyridine); (poly(GMA-MAA)), poly(glycidyl methacrylate-methacrylic acid); (PVA), polyvinyl alcohol; (RBBR), Remazol Brilliant Blue R; (SDE), simulated dye effluent; (semi-IPNs), semi-interpenetrating polymer networks; (TC), tetracycline; (TCH), tetracycline hydrochloride; (TCS), triclosan; (Vmax), maximum activity; (Zr-MOF, MMU), micro-mesoporous Zr-metal organic framework.

Co-immobilization of laccase and ABTS onto amino-functionalized ionic liquid-modified magnetic chitosan nanoparticles for pollutants removal

This work aims to achieve the co-immobilization of laccase and 2,2-binamine-di-3-ethylbenzothiazolin-6-sulfonic acid (ABTS) to improve removal capability of the biocatalyst for pollutants while avoiding potential pollution caused by ABTS. The laccase was immobilized on magnetic chitosan nanoparticles modified with amino-functionalized ionic liquid containing ABTS (MACS-NIL) based on Cu ion chelation (MACS-NIL-Cu-lac). The carrier was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, x-ray diffraction and etc., and electron paramagnetic resonance confirmed the mediator molecule ABTS on the carrier could also play the role of electron transmission. MACS-NIL-Cu-lac presented relatively high immobilization capacity, enhanced activity (1.7-fold that of free laccase), improved pH and temperature adaptability, and increased thermal and storage stability. The removal performance assay found that MACS-NIL-Cu-lac had a good removal efficiency with 100.0 % for 2,4-dichlorophenol in water at 25 °C, even when the concentration reached 50 mg/L. Reusability study showed that after six catalytic runs, the removal efficiency of 2,4-dichlorophenol by MACS-NIL-Cu-lac could still reach 93.2 %. Additionally, MACS-NIL-Cu-lac exhibited higher catalytic efficiencies with 100.0 %, 70.5 % and 93.3 % for bisphenol A, indole, and anthracene, respectively. The high catalytic performance in pure water system obtained by the novel biocatalyst co-immobilizing laccase and electron mediator ABTS showed greater practical application value.

Bioremediation of intertidal zones polluted by heavy oil spilling using immobilized laccase-bacteria consortium

Heavy oil pollution in the intertidal zones has become a worldwide environmental problem. In this study, bioremediation on heavy oil pollutants in the intertidal zones using an immobilized laccase-bacteria consortium system was evaluated with the aid of intertidal experimental pools built in the coastal area. It is found that degradation efficiency of the immobilized laccase-bacteria consortium for heavy oil was 66.5% after 100 days remediation, with the reaction rate constant of 0.018 d^-1. Gas Chromatograph-Mass Spectrometer analysis shows that degradation efficiency of saturated hydrocarbons and aromatic hydrocarbons were 79.2% and 78.7%, which were 64.9% and 65.1% higher than control. It is further seen that degradation of long-chain n-alkanes of C26-C35 and polycyclic aromatic hydrocarbons with more than three rings were significant. Metagenomic analysis indicates that the immobilized laccase-bacterial consortium has not only increased the biodiversity of heavy oil degrading bacteria, but also accelerated the degradation of heavy oil.

LC-MSMS based screening of emerging pollutant degradation by different peroxidases

BACKGROUND

The presence of a wide range of bioactive organic pollutants in wastewater and municipal water sources is raising concerns about their potential effects on humans. Not surprisingly, various approaches are being explored that can efficiently degrade these persistent organic pollutants. Use of peroxidases has recently been recognized as a novel remediation approach that may have potential advantages over conventional degradation techniques. However, testing the abilities of different peroxidases to degrade diverse emerging pollutants is tedious and cumbersome.

RESULTS

In the present study, we present a rapid and robust approach to easily test the degradability of 21 different emerging pollutants by five different peroxidases (soybean peroxidase, chloroperoxidase, lactoperoxidase, manganese peroxidase, and horseradish peroxidase) using an LC-MSMS approach. Furthermore, this approach was also used to examine the role of a redox mediator in these enzymatic degradation assays. Our results show that some of the organic pollutants can be easily degraded by all five of the peroxidases tested, whereas others are only degraded by a specific peroxidase (or when a redox mediator was present) and there are some that are completely resistant to degradation by any of the peroxidases tested (even in the presence of a redox mediator). The degradation of furosemide and trimethoprim by soybean peroxidase and chloroperoxidase, respectively, was investigated in detail by examining the transformation products generated during their degradation. Some of the products generated during enzymatic breakdown of these pollutants have been previously reported by others, however, we report many new transformation products.

CONCLUSIONS

LC-MSMS approaches, like the one described here, can be used to rapidly evaluate the potential of different peroxidases (and redox requirements) to be used as bioremediation agents. Our preliminary result shows peroxidases hold tremendous potential for being used in a final wastewater treatment step.

Removal of nine pesticide residues from water and soil by biosorption coupled with degradation on biosorbent immobilized laccase

Biosorbents prepared with peanut shell and wheat straw were act as supports for the immobilization of Aspergillus laccase, and the redox mediator syringaldehyde (SA) was used to improve laccase-catalyzed degradation of nine pesticide residues, including isoproturon, atrazine, prometryn, mefenacet, penoxsulam, nitenpyram, prochloraz, pyrazosulfuron-ethyl and bensulfuron-methyl. Pesticides in water and soil samples were effectively removed via biosorbent concentration and subsequent immobilized laccase degradation on peanut shell or wheat straw supports. The Langmuir equation and Freundlich equation described the biosorption isotherms of the nine pesticides. Parameters that affect the degradation was also investigated. With concentration of pesticides and SA of 6.0 mg L^-1 and 1 mmol L^-1, over 54.5% and 65.9% of pesticides were removed in water in 3 days with a biosorbent immobilized laccase dose of 25 g L^-1 for peanut shell immobilized laccase and wheat straw immobilized laccase, respectively. In the treatment of pesticide in soil with a biosorbent dose of 50 g (kg soil)^-1, with the maximum degradation rates ranged from 20.9 to 92.9% and 14.7-92.0% in 7 days for peanut shell immobilized laccase and wheat straw immobilized laccase, respectively. Therefore, laccase immobilized on biomass materials has a strong potential for the effective removal of pesticide pollutants from water and soil by biosorption coupled with degradation.

Study on transformation and degradation of bisphenol A by Trametes versicolor laccase and simulation of molecular docking

As a typical class of environmental endocrine disruptors, bisphenol A poses a potential threat to the sustainable survival and reproduction of living beings and human beings. In this study, the interaction between Trametes versicolor laccase and bisphenol A (BPA) was studied by molecular docking simulation, and the catalytic degradation of BPA was verified by experiments. The conditions for the laccase production of T. versicolor were optimized by orthogonal design, and the degradation of BPA was studied using its crude enzyme solution. The optimum degradation conditions were obtained by response surface methodology (RSM). Ultimately, the transformation products after 3 and 6 h of reaction were detected by gas chromatography-mass spectrometry. Docking results demonstrated that the reaction between laccase and BPA was spontaneous, and the degradation rate in 24 h reached 88.76%. RSM results showed that the highest BPA degradation rate of 97.68% was reached after 1 h reaction at 44.6 °C, 5 mg/L initial BPA concentration, and pH 5.20. The intermediate products of BPA catalyzed by laccase included ethylbenzene, p-xylene, and cyclohexanone 1-methyl-4-isopropenyl-2-cyclohexenol. This finding reveals that BPA degradation by the crude laccase from T. versicolor starts from the C atoms between two benzene rings that connect BPA. Compared with expensive pure enzyme, the crude laccase solution prepared by T. versicolor showed greater efficiency in BPA degradation. This work provides theoretical references and experimental methods for the biological processing of harmful pollutants.

Biodegradation potential of polycyclic aromatic hydrocarbons by immobilized Klebsiella sp. in soil washing effluent

A strain KL (Klebsiella sp.), with a high polycyclic aromatic hydrocarbons (PAHs) degradation efficiency, was isolated and purified. Immobilization of strain KL using a boric acid-CaCl₂ cross-linking method based on polyvinyl alcohol (PVA)-sodium alginate (SA)-nano alumina (ALNPs) composite was investigated for removal of phenanthrene (PHE), fluoranthene (FLA), and pyrene (PYR) in soil washing effluent. The concentration of PVA, SA, and ALNPs in immobilized beads had significant effects on the physicochemical properties and biodegradation performance. When beads had a PVA, SA, and ALNPs content of 10% (w/v), 0.8% (w/v), and 0.7% (w/v), and the initial biomass dosage was 10% (v/v), the biodegradation efficiency and mass transfer performance of the immobilized beads were optimal with the specific surface area of 13.3971 m²/g. Scanning electron microscopy (SEM) showed that the surface of immobilized beads was dense. The growth and adhesion of cells inside the beads were adequate, and pores of the beads were abundant and irregularly staggered. The immobilization method was successfully applied to the treatment of the three PAHs in soil washing effluent. Adsorption of beads contributed to PAHs removal in the initial stage of degradation. Higher residual concentrations of Tween 80 in the soil washing effluent have toxic effects on strain KL growth and reduce the PAHs degradation capacity. Tween 80 of 2500 mg/L was proper conditions for PAHs biodegradation efficiency. Compared to freely suspended KL cells, the removal rates of PHE, FLA, and PYR using the immobilization method on the 30th day were increased by 15.91%, 17.07%, and 19.08%, respectively.

Biodegradation of Cibacron Blue 3GA by insolubilized laccase and identification of enzymatic byproduct using MALDI-ToF-MS: Toxicity assessment studies by Daphnia magna and Chlorella vulgaris

The presented paper describes a detailed study on the use of immobilized laccase for effective degradation of Cibacron Blue 3GA dye. The amount of laccase loading on the cyclic carbonate groups containing poly(hydroxyethyl methacrylate-co-vinylene carbonate), p(HEMA-co-VC), microbeads was 27.8 mg g^-1, and the retained immobilized enzyme activity was 73% compared to free enzyme. The toxicity of the dye and its byproducts were studied using Daphnia magna as test organism. The micro-algal growth inhibition was also studied using a green micro algae "Chlorella vulgaris". MALDI-ToF-MS was used to verify dye degradation byproducts. After 60 min of incubation period, Cibacron Blue 3GA (CB3GA) and its byproducts disappeared from the medium. After 60-min enzymatic treatment, the non-toxic nature of medium was confirmed by toxicity studies. On the other hand, the initial byproducts of the dye seemed to be more toxic than the later formed dye products. It should be noted that the information obtained from this study can be beneficial for understanding the initial degradation byproducts toxicities of the enzymatically treated dyes to provide information about environmental protection.

Bio-interfactants as double-sided tapes for graphene oxide

We present a versatile and highly substrate-independent approach for preparing multisandwich layers based on thermally reduced Graphene Oxide (rGO) which gets strongly attached by bio-interfactants using a layer-by-layer (LBL) aqueous dipping and rinsing process. The process allows for the deposition of homogeneous ultra-thin films (∼5.5 nm) in distinct surface topographies, thicknesses and compositions by varying the bio-interfactant layer(s). The layers formed on quartz or other semi conductive material are electrically conductive, flexible, and transparent. The here-developed approach could be applied for the fabrication of wearables, sensors, and antistatic transparent films.

Tailored Design of Differently Modified Mesoporous Materials To Deeply Understand the Adsorption Mechanism for Polycyclic Aromatic Hydrocarbons

A series of SBA-15 with different modifications have been successfully prepared and applied as adsorbents to remove polycyclic aromatic hydrocarbons (PAHs) from aqueous solutions. The morphology and structural properties of the chemically modified materials are all similar to those of pure SBA-15, and thus the difference of PAHs adsorption capacity can be directly attributed to the different functional groups, which is favorable to deeply explore the adsorption mechanism. Adsorption kinetics and isotherm experiments for naphthalene (Nap), anthracene (Ant), and pyrene (Pyr) were carried out, and the results reveal that the adsorption processes follow a pseudo-second-order rate equation and the equilibrium can be achieved within 120 min for Nap and Ant, whereas only 90 min for Pyr, indicating that the more hydrophobic molecules, the easier and faster adsorption can be obtained. All of the adsorption isotherms fit well with the Freundlich model, suggesting the unevenly distributed active sites on adsorbents. The phenyl-functionalized materials possess the highest adsorption capacity, implying that the π-π interaction is the most primary interaction and plays the predominant role in the studied PAHs adsorption, superior to the acidic and hydrophobic interaction. Our research sheds light on the design and synthesis of advanced and highly efficient adsorbents to remove PAHs from aqueous solutions.

Potential of Trichoderma koningii to eliminate alachlor in the presence of copper ions

The filamentous fungus Trichoderma koningii is capable of fast and effective eliminate alachlor (90% after 72 h when added separately and 80-60% in the presence of 1-5 mM of copper). After 168 h over 99% elimination of alachlor resulted in detoxification and was connected with the mitigation of reactive oxygen species (ROS) production. Using MS/MS techniques, seven dechlorinated and hydroxylated metabolites were identified. Cytochrome P450 and laccase participate in biotransformation of the herbicide by this non-ligninolytic fungus. Laccase activity is stimulated both by copper and the mixture of copper and alachlor, which seems to be important for combined pollutants. T. koningii is characterized by high tolerance to copper (up to 7.5 mM). The metal content in mycelia reached 0.9-7.76 mg in 1 g of dry biomass. Our results suggest that T. koningii strain seems to be a promising tool for bioremediation of agricultural areas co-contaminated with copper-based fungicides and chloroacetanilide herbicides.

Immobilizing Laccase on Different Species Wood Biochar to Remove the Chlorinated Biphenyl in Wastewater

Biochars produced from two different wood species over a microwave assisted pyrolysis process were used as novel and green-based supports for immobilizing enzyme, laccase in particular. The results obtained from FT-IR, SEM and BET measurements indicated that Maple biochar with honeycomb structure has higher surface area and pore volume than Spruce biochar; and there exist O-H, C-H, C=O and C=C groups in biochars for potential chemical modification. The best laccase immobilization conditions identified from an orthogonal experiment were pH = 3, laccase concentration 16 g/L and contact time 8 h. Under such conditions, the high immobilization yield (64.2%) and amount (11.14 mg/g) of laccase on Maple biochar were achieved, leading to the significantly improved thermal stability of laccase. Moreover, the immobilized laccase is reusable and enhanced the enzymatic degradation of 4-hydroxy-3,5-dichlorobiphenyl (71.4% yield), thus creating a promising and novel type of adsorbent in the removal of polychlorinated biphenyls from wastewater.

Immobilizing Laccase on Modified Cellulose/CF Beads to Degrade Chlorinated Biphenyl in Wastewater

Novel modified cellulose/cellulose fibril (CF) beads (MCCBs) loaded with laccase were prepared to degrade polychlorinated biphenyls (PCBs) in wastewater. The proper porous structure in MCCBs was achieved by introducing nano CaCO₃ (as a pore forming agent) in cellulose/CF (CCBs) beads during the preparation process. Cellulose/CF composite beads were modified by maleic anhydride to introduce carboxyl groups. Laccase was immobilized on the MCCBs through electrostatic adsorption and covalent bonding. The effects of pH, laccase concentration and contact time on immobilization yields and recovered activity were investigated. The best conditions were pH 4, concentration 16 g/L and contact time 3 h. The immobilized laccase under these conditions showed a good performance in thermal and operational stability. The laccase immobilized on MCCB beads can remove 85% of 20 mg/L 4-hydroxy-3,5-dichlorobiphenyl (HO-DiCB) in wastewater. The results demonstrated that MCCBs, as a new type of green-based support, are very promising in material immobilizing laccase. This technology may be of potential advantage for the removal of polychlorinated biphenyls in wastewater from an environmental point of view.

Optimizing Reductive Degradation of PAHs Using Anhydrous Ethanol with Magnesium Catalyzed by Glacial Acetic Acid

Targeted degradation of individual polycyclic aromatic hydrocarbon (PAH) constituents like anthracene, may offer cost effective and efficient cleaning of coal tar-contaminated sites. Thus, a reductive degradation procedure of anthracene using activated magnesium with anhydrous ethanol at room temperature was developed and optimized. To determine the optimum conditions for anthracene, such as effective magnesium concentrations, glacial acetic acid volumes, and exposure time for the anthracene reduction, the experiments were designed using the response surface methodology based on the central composite design. The design also minimized the number of experiments. The main product from anthracene reduction is 9,10-dihyrdoanthracene. Optimum conditions for 98% degradation capacity of anthracene (2.80 × 10^-3 mmol) were 30 mg of Mg powder (1.20 mmol), 60 μL of glacial acetic acid (1.05 mmol), and 30 min exposure time. When the optimized method was tested on the coal tar specimen, twice as many reagents (i.e., Mg and glacial acetic acid) were required to obtain a 90% degradation of anthracene and fluoranthene from the coal tar. This method of using activated Mg and anhydrous ethanol selectively reduces PAHs in coal tar; in particular anthracene and fluoranthene are most efficiently removed.

Emergent contaminants: Endocrine disruptors and their laccase-assisted degradation - A review

Herein, an effort has been made to highlight the trends of the state-of-the-art of laccase-assisted degradation of emerging contaminants at large and endocrine disruptors in particular. Since first described in the 19th century, laccase has received particular interest for inter- and multidisciplinary investigations due to its uniqueness and remarkable biotechnological applicability. There has always been a paramount concern over the widespread occurrences of various pollutant types, around the globe. Therefore, pollution free processes are gaining ground all over the world. With ever increasing scientific knowledge, socioeconomic awareness, human health-related issues and ecological apprehensions, people are more concerned about the widespread environmental pollutants. In this context, the occurrences of newly identified pollutants so-called "emerging contaminants - ECs" in our main water bodies is of continued and burning concern worldwide. Undoubtedly, various efforts have already been made to tackle this challenging ECs concern though using different approaches including physical and chemical, however, each has considerable limitations. In this review, we present information on how laccase-assisted approach can change this limited tendency of physical and chemical based approaches. A special focus has been given to the laccase-assisted systems including pristine laccase, laccase-mediator catalyzed system and immobilized-laccase catalyzed system that promotes the endocrine disruptors removal. Towards the end, a list of outstanding questions and research gaps are given that can pave the way for future studies.

Degradation of the herbicide paraquat by macromycetes isolated from southeastern Mexico

Fifty-four macromycetes, isolated from southeastern Mexico, were used in order to evaluate their capacity for degradation and tolerance to the herbicide paraquat. Ten of these strains were capable of growing in a solid culture medium in the presence of 200 ppm paraquat. Subsequently, assays to evaluate the degradation of the xenobiotic in a liquid medium were carried out. Of the ten strains evaluated, three presented the highest levels of degradation of the compound, which were Trametes pavonia (54.2%), Trametes versicolor (54.1%) and Hypholoma dispersum. They presented the highest overall degradation percentage (70.7%) after 12 days culture. The presence of ligninolytic enzymes in these strains was evaluated. H. dispersum only presented aryl alcohol oxidase activity; however, with the data obtained, it was not possible to conclude whether this specific enzyme is responsible for paraquat degradation. The level of degradation obtained is above the one reported for Pseudomonas putida, one of the few reports on paraquat degradation. This is the first report on the contaminant degradation capacity of H. dispersum.

By-product identification and phytotoxicity of biodegraded Direct Yellow 4 dye

Citrus limon peroxidase mediated decolourization of Direct Yellow 4 (DY4) was investigated. The process variables (pH, temperature, incubation time, enzyme dose, H₂O₂ amount, dye concentration, co-metal ions and surfactants) were optimized for maximum degradation of dye. Maximum dye decolourization of 89.47% was achieved at pH 5.0, temperature 50 °C, enzyme dose 24 U/mL, H₂O₂ concentration 0.25 mM and DY4 concentration 18.75 mg/L and incubation time 10 min. The co-metal ions and surfactants did not affect the dye decolourization significantly. Response surface analysis revealed that predicted values were in agreement with experimentally determined responses. The degradation products were identified by UPLC/MS analysis and degradation pathway was proposed. Besides, phytotoxicity assay revealed a considerable detoxification in response of biodegradation of DY4 dye. C. limon showed promising efficiency for DY4 degradation and could possibly be used for the remediation of textile effluents.

Extraction techniques using isopropanol and Tenax to characterize polycyclic aromatic hydrocarbons bioavailability in sediment

Polycyclic aromatic hydrocarbon (PAH)-degrading bacterium strain J1-q (Sphingomonas pseudosanguinis strain J1-q) was isolated from Yangtze River surface sediment in the downtown area of Chongqing in a previous study. Isopropanol and Tenax extraction techniques were used to characterize the bioavailability of target PAH compounds. Phenanthrene (Phe) and fluoranthene (Fluo) were the target PAHs due to their significant background concentrations in surface sediment samples. Isopropanol solutions at concentrations of 50-100% and residual Phe and Fluo concentrations in sediment were correlated, with R² values of 0.9846 and 0.9649, respectively. The quantities of the Phe and Fluo fractions extracted for 3days with isopropanol from sediment were closely related with the corresponding quantities of PAHs degraded by bacterial strain J1-q when the extracting concentrations were 55% and 80%, respectively. The quantity of Phe extracted by Tenax agreed with the total quantity biodegraded when the Tenax: sediment mass ratio was 0.25 and the target PAHs were degraded for 30d, whereas the extracted quantity of Fluo accounted for 93.30% of the total quantity biodegraded by the bacterium. The triphasic model was appropriate to simulate the consecutive Phe and Fluo extraction process using Tenax at various Tenax: sediment ratios, and all simulated correlation coefficients were >0.9151. A 24-h extraction period was adequate to estimate the rapidly desorbing fractions when they were extracted with Tenax. Isopropanol extraction was preferable to characterize Phe and Fluo bioavailability under the experimental conditions, whereas Tenax extraction was useful to predict bioavailability of the two target PAHs with particular selectivity.

Current advances in the utility of functionalized SBA mesoporous silica for developing encapsulated nanocatalysts: state of the art

The cavities of SBA mesoporous silica materials can be used as nanoreactors for embedding catalytic species such as nanoparticles, complexes and heteropolyacids etc.

Biodegradation of lignin and nicotine with white rot fungi for the delignification and detoxification of tobacco stalk

BACKGROUND

Tobacco stalk is one kind of abundant crop residues in China. The high lignification of tobacco stalk increases its reusing cost and the existing of nicotine will cause serious pollution. The biodegradation of lignocellulosic biomass has been demonstrated to be an environmental and economical approach for the utilization of plant stalk. Meanwhile, many nicotine-degrading microorganisms were found in nature. However, microorganisms which could degraded both nicotine and lignin haven't been reported. Therefore, it's imperative to find some suitable microorganisms to break down lignin and simultaneously remove nicotine in tobacco stalk.

RESULTS

The nicotine in tobacco stalk could be degraded effectively by Trametes versicolor, Trametes hirsute and Phanerochaete chrysosporium. The nicotine content in tobacco stalk was lowered to below 500 mg/kg (a safe concentration to environment) after 10 days of fermentation with Phanerochaete chrysosporium and Trametes versicolor, and 15 days with Trametes hirsute. The degradation rate of lignin in the fermented tobacco stalk was 37.70, 51.56 and 53.75% with Trametes versicolor, Trametes hirsute and Phanerochaete chrysosporium, respectively. Meanwhile, 24.28% hemicellulose was degraded by Phanerochaete chrysosporium and 28.19% cellulose was removed by Trametes hirsute. Through the enzyme activity analysis, the main and highest ligninolytic enzymes produced by Phanerochaete chrysosporium, Trametes hirsute and Trametes versicolor were lignin peroxidase (88.62 U · L-1), manganese peroxidase (100.95 U · L-1) and laccase (745.65 U · L-1). Meanwhile, relatively high and stable cellulase activity was also detected during the fermentation with Phanerochaete chrysosporium, and the highest endoglucanase, exoglucanase and filter paper enzyme activities were 0.38 U · mL-1, 0.45 U · mL-1 and 0.35U · mL-1, respectively. Moreover, the products in the fermentation of tobacco stalk with P. chrysosporium were identified with GC-MS, besides the chemicals produced in the degradation of lignin and nicotine, some small molecular valuable chemicals and fatty acid were also detected.

CONCLUSIONS

Our study developed a new method for the degradation and detoxification of tobacco stalk by fermentation with white rot fungi Phanerochaete chrysosporium and Trametes hirsute. The different oxidative enzymes and chemical products detected during the degradation indicated a possible pathway for the utilization of tobacco stalk.

Immobilization of laccase on functionalized multiwalled carbon nanotube membranes and application for dye decolorization

Myceliophthora thermophilalaccase was covalently immobilized on functionalized multiwalled carbon nanotubes (MWNT) arranged over a supporting membrane to obtain a permeable bio-barrier that could be applied in multibatch or continuous processes.