Reversible immobilization of laccase to poly(4-vinylpyridine) grafted and Cu(II) chelated magnetic beads: biodegradation of reactive dyes

Recent Advances in Applications of Oxidases and Peroxidases Polymer-Based Enzyme Biocatalysts in Sensing and Wastewater Treatment: A Review

Oxidase and peroxidase enzymes have attracted attention in various biotechnological industries due to their ease of synthesis, wide range of applications, and operation under mild conditions. Their applicability, however, is limited by their poor stability in harsher conditions and their non-reusability. As a result, several approaches such as enzyme engineering, medium engineering, and enzyme immobilization have been used to improve the enzyme properties. Several materials have been used as supports for these enzymes to increase their stability and reusability. This review focusses on the immobilization of oxidase and peroxidase enzymes on metal and metal oxide nanoparticle-polymer composite supports and the different methods used to achieve the immobilization. The application of the enzyme-metal/metal oxide-polymer biocatalysts in biosensing of hydrogen peroxide, glucose, pesticides, and herbicides as well as blood components such as cholesterol, urea, dopamine, and xanthine have been extensively reviewed. The application of the biocatalysts in wastewater treatment through degradation of dyes, pesticides, and other organic compounds has also been discussed.

Applications and immobilization strategies of the copper-centred laccase enzyme; a review

Laccase is a multi-copper enzyme widely expressed in fungi, higher plants, and bacteria which facilitates the direct reduction of molecular oxygen to water (without hydrogen peroxide production) accompanied by the oxidation of an electron donor. Laccase has attracted attention in biotechnological applications due to its non-specificity and use of molecular oxygen as secondary substrate. This review discusses different applications of laccase in various sectors of food, paper and pulp, waste water treatment, pharmaceuticals, sensors, and fuel cells. Despite the many advantages of laccase, challenges such as high cost due to its non-reusability, instability in harsh environmental conditions, and proteolysis are often encountered in its application. One of the approaches used to minimize these challenges is immobilization. The various methods used to immobilize laccase and the different supports used are further extensively discussed in this review.

Utilization of laccase immobilized CdO nanoparticles in synthesis of industrially potent organics and their molecular docking studies

In the present study, Tricholoma giganteum AGHP laccase was immobilized on amino-functionalized cadmium oxide nanoparticles (CdO NPs) which was carried out by glutaraldehyde. The synthesized CdO NPs were characterized by using transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDXA) and X-ray diffraction (XRD) analysis which reflected the NPs had an average size of 35 nm with hexagonal and irregular shapes. Fourier transform infra-red (FTIR) study of laccase with amino-functionalized CdO (lac-CdO) NPs confirmed the crosslinking of laccase with CdO NPs. With immobilized laccase, a shift in pH (5.5) and temperature (35 ℃) optima was observed, when compared to free laccase (pH 4.5, 30 ℃). Lac-CdO NPs displayed 1.15 times higher stability (90 ± 0.47%) than free laccase (78 ± 0.69%) at optimum pH of 5.5. Immobilized laccase showed 1.19-fold improvement in thermal stability and 2.25-fold increment in half-life after 3 h of incubation at 50 ℃ as compared to free laccase. Recycling capability study demonstrated that lac-CdO NPs were able to retain 85 ± 0.68% of relative activity at the end of 20th 2,2-azinobis-3-ethylbenzthiozoline-6-sulfonic acid (ABTS) oxidation cycle. In addition, lac-CdO NPs showed remarkable reusability in catalysing various organic synthesis reactions even after several cycle of catalysis. Furthermore, the interactions of organic synthesis reactions and interacted residues were observed by assessing the molecular docking poses of T. giganteum laccase with substrates. The obtained results would be advantageous to develop a biocatalyst over a chemical catalyst for effective synthesis of potent organics having industrial importance.

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.

Synthesis of cross-linked magnetic chitosan beads immobilised with bacteria for aerobic biodegrading benzophenone-type UV filter

Bacterial immobilisation is a technique by which bacteria are embedded into or adsorbed onto a carrier material thereby increasing bacterial tolerance to harsh environments. This technique can be used to enhance bacterial activity and to degrade pollutants. Immobilised bacterial beads that contain nanomagnetic particles allow bead recycling and reuse. In this study, our objective was to produce cross-linked nanomagnetic chitosan beads (MCBs) for the biodegradation of benzophenone-type UV filter chemicals such as 2,4-dihydroxybenzophenone (BP-1) and oxybenzone (BP-3). We found that the optimal concentration for creating these MCBs to be 1.2% by weight chitosan and 10% by weight nano-magnetite. We selected and isolated six benzophenone-n (BPs)-biodegrading bacteria identified to be various Pseudomonas spp., a Gordonia sp., and Rhodococcus zopfii; these were used to create MCBs that were able to effectively biodegrade BP-1 or BP-3 as a sole carbon source. Both BPs were effectively biodegraded and mineralised over 8 days in the presence of the selected MCB-immobilised bacterial strains. The highest pseudo-first-order constant rates for BP biodegradation were 8.7 × 10^-3 h^-1 for BP-1 (strain BP1-D) and 1.02 × 10^-3 h^-1 for BP-3 (strain BP3-1). The mechanical strength of the MCBs was measured to be above 90% based on recovered weight. The MCBs released their bacteria at rates in the range of 10⁴-10⁵ CFU/day. We also determined the pathway through which the BPs were being aerobically biodegraded based on the GC/MS profiles of the intermediates. Our findings provide a novel strategy for treating BPs via the use of reusable and recyclable MCBs that are cheap, easy and fast to synthesise.

Non-magnetic and magnetically responsive support materials immobilized peroxidases for biocatalytic degradation of emerging dye pollutants-A review

In recent years, the removal of hazardous pollutants from many industries has become a significant challenge for mankind as a growing number of contaminants, including a wide range of organic pollutants, synthetic dyes, and polycyclic aromatic hydrocarbons (PAHs), have inevitably led to an increased anthropogenic impact on the biosphere. Due to the complex aromatic structure, most synthetic dyes show resistance to degrade by the classical approaches, such as coagulation, flotation, adsorption, membrane process, and reverse osmosis. Enzyme-assisted biodegradation of pollutants offers an eco-friendlier and cost-effective alternative to remediate dyes, dyes-based effluents, other toxins, etc. Various plant and microbial oxidoreductase (Horseradish and manganese peroxidase) have recently received more attention for degrading and detoxifying a wide range of dyes either by opening the aromatic ring structure or by precipitation due to their high activity under milder conditions, high substrate specificity, and biodegradable nature. To enhance the efficiency, stability and recyclability, enzymes were immobilized on various support media such as sodium alginate, agarose, chitin/chitosan, polyvinyl alcohol, polyacrylamide, macroporous exchange resins, hydrophobic sol-gels, and nanoporous silica gel, including magnetically separatable media. Among various types of magnetic nanoparticles (MNPs), iron oxide magnetic nanoparticles, such as hematite, magnetite, and maghemite, have gained great attention due to their properties like small size, superparamagnetism, high surface area to volume ratio, and ease of separation for repeated cycles of uses. These carriers can be separated easily and rapidly from the reaction medium by an external magnetic field without being subjected to mechanical stress than centrifugation or filtration. Various methods have been employed for immobilizing oxidoreductase on different media, such as adsorption, covalent binding, entrapment, and encapsulation using different cross-linking agents. Compared to the free enzyme, insolubilized enzymes reduce production costs by enzyme reusability, tolerance to unfavorable environmental conditions, and high catalytic stability. Here, we review various immobilization methods and biocatalytic degradation of emerging dye pollutants, focusing on various non-magnetically and magnetically responsive supports to immobilize peroxidases. Conclusively, magnetically separatable peroxidases show more stability towards extreme temperature and pH conditions and can be used for repeated cycles than free and non-magnetically separatable peroxidase.

Improvement of Laccase Activity Via Covalent Immobilization over Mesoporous Silica Coated Magnetic Multiwalled Carbon Nanotubes for the Discoloration of Synthetic Dyes

Due to its environmental friendliness and biodegradable ability, the enzymatic decolorization of azo dyes is the best option. However, the free enzyme suffers from various limitations, including poor stability, no repeatable use, and a high expense, which is the key drawback for its practical use. In this analysis, the laccase enzyme was immobilized in mesoporous silica coated magnetic multiwalled carbon nanotubes (Fe₃O₄-MWCNTs@SiO₂) by a glutaraldehyde cross-linker to create an easily separable and stable enzyme. Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX) were used to characterize the as-synthesized Fe₃O₄-MWCNTs@SiO₂. Laccase immobilized in Fe₃O₄-MWCNTs@SiO₂ showed a good improvement in temperature, pH, and storage stability. Moreover, the operational stability of the biocatalyst was improved, retaining 87% of its original activity even after 10 cycles of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) oxidation. The biocatalysts were applied for the decolorization of selected azo dyes without a mediator, and up to 99% of Eriochrome Black T (EBT), 98% of Acid Red 88 (AR 88), and 66% of Reactive Black 5 (RB5) were decolorized. Based on these properties, the biocatalysts can be potentially utilized in various environmental and industrial applications.

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.

Process intensification using immobilized enzymes for the development of white biotechnology

Process intensification of biocatalysed reactions using different techniques such as microwaves, ultrasound, hydrodynamic cavitation, ionic liquids, microreactors and flow chemistry in various industries is critically analysed and future directions provided.

Tunable Polymeric Scaffolds for Enzyme Immobilization

The number of methodologies for the immobilization of enzymes using polymeric supports is continuously growing due to the developments in the fields of biotechnology, polymer chemistry, and nanotechnology in the last years. Despite being excellent catalysts, enzymes are very sensitive molecules and can undergo denaturation beyond their natural environment. For overcoming this issue, polymer chemistry offers a wealth of opportunities for the successful combination of enzymes with versatile natural or synthetic polymers. The fabrication of functional, stable, and robust biocatalytic hybrid materials (nanoparticles, capsules, hydrogels, or films) has been proven advantageous for several applications such as biomedicine, organic synthesis, biosensing, and bioremediation. In this review, supported with recent examples of enzyme-protein hybrids, we provide an overview of the methods used to combine both macromolecules, as well as the future directions and the main challenges that are currently being tackled in this field.

Synthesis of magnetic nanoparticles with an IDA or TED modified surface for purification and immobilization of poly-histidine tagged proteins

Magnetic nanoparticles (MNPs) chelating with metal ions can specifically interact with poly-histidine peptides and facilitate immobilization and purification of proteins with poly-histidine tags. Fabrication of MNPs is generally complicated and time consuming. In this paper, we report the preparation of Ni(ii) ion chelated MNPs (Ni-MNPs) in two stages for protein immobilization and purification. In the first stage, organic ligands including pentadentate tris (carboxymethyl) ethylenediamine (TED) and tridentate iminodiacetic acid (IDA) and inorganic Fe₃O₄–SiO₂ MNPs were synthesized separately. In the next stage, ligands were grafted to the surface of MNPs and MNPs with a TED or IDA modified surface were acquired, followed by chelating with Ni(ii) ions. The Ni(ii) ion chelated forms of MNPs (Ni-MNPs) were characterized including morphology, surface charge, structure, size distribution and magnetic response. Taking a his-tagged glycoside hydrolase DspB (Dispersin B) as the protein representative, specific interactions were confirmed between DspB and Ni-MNPs. Purification of his-tagged DspB was achieved with Ni-MNPs that exhibited better performance in terms of purity and activity of DspB than commercial Ni-NTA. Ni-MNPs as enzyme carriers for DspB also exhibited good compatibility and reasonable reusability as well as improved performance in various conditions.

This article reports a novel approach for synthesizing magnetic nanoparticles with a modified surface for purification and immobilization of histidine-tagged proteins.

Magnetic nanoparticles encapsulated laccase nanoflowers: evaluation of enzymatic activity and reusability for degradation of malachite green

Magnetic laccase nanoflowers (MNFs-Lac) were successfully prepared through encapsulating Fe₃O₄ magnetic nanoparticles into the interior of laccase nanoflowers by grafting N-(phosphonomethyl)iminodiacetic acid (PMIDA) as an interconnecting bridge between the magnetic nanoparticles and copper ions. The characterizations by scanning electron microscopy and transmission electron microscopy showed that MNFs-Lac were spherical, porous and flower-like crystals with diameters of ∼10 μm, and Fe₃O₄ nanoparticles were encapsulated in the interior of MNFs-Lac evenly. The enzymatic activity and reusability of MNFs-Lac were evaluated based on the degradation efficiency for malachite green (MG). The degradation parameters, concerning initial MG concentration, dosage of MNFs-Lac, reaction temperature, pH value and reaction time, were optimized through single-factor experiments. Under the optimal conditions, 25 mg·L^-1 MG can be degraded almost completely by 1.5 g·L^-1 MNFs-Lac within 15 min. When the MNFs-Lac were reused for 18 times, the degradation efficiency of MG was still as high as 90%. These results suggested that the modified preparation method improved greatly the reusability of MNFs-Lac, which made them more suitable to degrade MG in a water environment.

Mitigation of bisphenol A using an array of laccase-based robust bio-catalytic cues - A review

Bisphenol A (BPA) is a known endocrine disruptor that poses concerning environmental and human-health related issues and ecological risks. It has been largely used as an intermediate in the manufacture of epoxy resins and polycarbonate plastics. Traces of BPA can reach into the environment through inadequate or inefficient removal during wastewater treatment, uncontrolled landfill leachates, and leaching out from the discarded BPA-based materials. Several physicochemical treatment methods including adsorption, Fenton, ozonation, electrochemical and photochemical degradation, and membrane filtration, have been applied for BPA elimination. However, these methods are not adequate for large-scale treatment due to some inherent limitations. Benefiting from high catalytic efficiency and specificity, enzyme-based bio-catalytic degradation strategies are considered quite meaningful alternative for efficient and effective BPA removal from different routes. Among various oxidoreductases, i.e., laccases exhibited a superior potential for the remediation of BPA-containing wastewater. Enzymatic oxidation of BPA can be boosted by using various natural or synthetic redox mediators. Immobilized enzymes can expand their applicability to continuous bioprocessing and facilitates process intensification. Therefore, optimized formulations of insolubilized biocatalysts are of strategic interest in the environmental biotechnology. In this review, recent research studies dealing with BPA removal by the laccase-catalyzed system are presented. At first, the presence of BPA in the ecosystem, sources, exposure, and its impact on the living organisms and human beings is summarized. Then, we highlighted the use of crude as well as immobilized laccases for the degradation of BPA. In addition to toxicity and estrogenicity removal studies, the unresolved challenges, concluding remarks, and possible future direction is proposed in this important research area. It is palpable from the literature reviewed that free as well as immobilized forms of laccases have displayed noteworthy potential for BPA removal from wastewater.

Laccase Immobilized onto Zirconia⁻Silica Hybrid Doped with Cu2+ as an Effective Biocatalytic System for Decolorization of Dyes

Nowadays, novel and advanced methods are being sought to efficiently remove dyes from wastewaters. These compounds, which mainly originate from the textile industry, may adversely affect the aquatic environment as well as living organisms. Thus, in presented study, the synthesized ZrO₂–SiO₂ and Cu²⁺-doped ZrO₂–SiO₂ oxide materials were used for the first time as supports for laccase immobilization, which was carried out for 1 h, at pH 5 and 25 °C. The materials were thoroughly characterized before and after laccase immobilization with respect to electrokinetic stability, parameters of the porous structure, morphology and type of surface functional groups. Additionally, the immobilization yields were defined, which reached 86% and 94% for ZrO₂–SiO₂–laccase and ZrO₂–SiO₂/Cu²⁺–laccase, respectively. Furthermore, the obtained biocatalytic systems were used for enzymatic decolorization of the Remazol Brilliant Blue R (RBBR) dye from model aqueous solutions, under various reaction conditions (time, temperature, pH). The best conditions of the decolorization process (24 h, 30 °C and pH = 4) allowed to achieve the highest decolorization efficiencies of 98% and 90% for ZrO₂–SiO₂–laccase and ZrO₂–SiO₂/Cu²⁺–laccase, respectively. Finally, it was established that the mortality of Artemia salina in solutions after enzymatic decolorization was lower by approx. 20% and 30% for ZrO₂–SiO₂–laccase and ZrO₂–SiO₂/Cu²⁺–laccase, respectively, as compared to the solution before enzymatic treatment, which indicated lower toxicity of the solution. Thus, it should be clearly stated that doping of the oxide support with copper ions positively affects enzyme stability, activity and, in consequence, the removal efficiency of the RBBR dye.

Hazardous contaminants in the environment and their laccase-assisted degradation - A review

In recent years, owing to the serious ecological risks and human health-related adverse effects, the wide occurrence of hazardous contaminants along with their potential to enter the environment have gained great public concerns. In this context, significant actions are urgently required to tackle the ignorance and inefficient monitoring/removal of emerging/(re)-emerging contaminants (ECs) in the environment from different routes of concerns, i.e., industrial waste, pharmaceutical, personal care products (PCPs), toxic effluents, etc. Laccases are multinuclear copper-containing oxidoreductases and can carry out one electron oxidation of a broad spectrum of environmentally related contaminants. In biotechnology, this group of versatile enzymes is known as a green catalyst/green tool with enormous potentialities to tackle ECs of high concern. In this review, we endeavored to present up-to-date literature concerning the potential use of immobilized laccases for the degradation and remediation of various types of environmental pollutants present in the environment. Both, pristine and immobilized, laccases have shown great capacity to oxidative degradation and mineralization of endocrine disrupting chemicals (EDs) in batch treatment processes as well as in large-scale continuous reactors. These properties make laccase as particularly attractive biocatalysts in environmental remediation processes, and their use might be advantageous over the conventional treatments. This review summarizes the most significant recent advances in the use of laccases and their future perspectives in environmental biotechnology.

Bifunctional in vivo role of laccase exploited in multiple biotechnological applications

Laccases are multicopper enzymes present in plants, fungi, bacteria, and insects, which catalyze oxidation reactions together with four electron reduction of oxygen to water. Plant, bacterial, and insect laccases have a polymerizing role in nature, implicated in biosynthesis of lignin, melanin formation, and cuticle hardening, respectively. On the other hand, fungal laccases carry out both polymerizing (melanin synthesis and fruit body formation) as well as depolymerizing roles (lignin degradation). This bifunctionality of fungal laccases can be attributed to the presence of multiple isoforms within the same as well as different genus and species. Interestingly, by manipulating culture conditions, these isoforms with their different induction patterns and unique biochemical characteristics can be expressed or over-expressed for a targeted biotechnological application. Consequently, laccases can be considered as one of the most important biocatalyst which can be exploited for divergent industrial applications viz. paper pulp bleaching, fiber modification, dye decolorization, bioremediation as well as organic synthesis. The present review spotlights the role of fungal laccases in various antagonistic applications, i.e., polymerizing and depolymerizing, and co-relating this dual role with potential industrial significance.

Developments in support materials for immobilization of oxidoreductases: A comprehensive review

Bioremediation, a biologically mediated transformation or degradation of persistent chemicals into nonhazardous or less-hazardous substances, has been recognized as a key strategy to control levels of pollutants in water and soils. The use of enzymes, notably oxidoreductases such as laccases, tyrosinases, various oxygenases, aromatic dioxygenases, and different peroxidases (all of EC class 1) is receiving significant research attention in this regard. It should be stated that immobilization is emphasized as a powerful tool for enhancement of enzyme activity and stability as well as for protection of the enzyme proteins against negative effects of harsh reaction conditions. As proper selection of support materials for immobilization and their performance is overlooked when it comes to comparing performance of immobilized enzyme in academic studies, this review summarizes the current state of knowledge regarding the materials used for enzyme immobilization of these oxidoreductase enzymes for environmental applications. In the presented study, thorough physicochemical characteristics of the support materials was presented. Moreover, various types of reactions and notably operational modes of enzymatic processes for biodegradation of harmful pollutants are summarized, and future trends in use of immobilized oxidoreductases for environmental applications are discussed. Our goal is to provide an improved foundation on which new technological advancements can be made to achieve efficient enzyme-assisted bioremediation.

Magnetic nanoparticles: a versatile carrier for enzymes in bio-processing sectors

Many industrial processes experience the advantages of enzymes which evolved the demand for enzymatic technologies. The enzyme immobilisation technology using different carriers has trustworthy applications in industrial biotechnology as these techniques encompass varied advantages such as enhanced stability, activity along with reusability. Immobilisation onto nanomaterial is highly favourable as it includes almost all aspects of science. Among the various techniques of immobilisation, the uses of nanoparticles are remarkably well perceived as these possess high-specific surface area leading to high enzyme loadings. The magnetic nanoparticles (MNPs) are burgeoning in the field of immobilisation as it possess some of the unique properties such as high surface area to volume ratio, uniform particle size, biocompatibility and particularly the recovery of enzymes with the application of an external magnetic field. Immobilisation of industrially important enzymes onto nanoparticles offers overall combined benefits. In this review, the authors here focus on the current scenario in synthesis and functionalisation of MNPs which makes it more compatible for the enzyme immobilisation and its application in the biotechnological industries.

Two contrary roles of Fe3O4 nanoparticles on kinetic and thermodynamic of Paclitaxel degradation by Citrobacter amalonaticus Rashtia immobilized on sodium alginate gel beads

Roles of Fe₃O₄ nanoparticles (NPs) on biodegradation of Paclitaxel by Citrobacter amalonaticus immobilized on alginate gel beads were investigated. Limitation in substrate diffusion is the major drawback of the cell immobilization method. To overcome this problem, bacterial cells were immobilized on the gel beads containing different concentrations (5-20mg/mL) of Fe₃O₄ NPs and their Paclitaxel degrading potential at different temperatures was investigated using kinetic and thermodynamic modeling. Co-immobilization of bacterial cells with 5, 10 and 20mg/mL Fe₃O₄ NPs enhanced biodegradation efficiencies to 66%, 80% and 78%, respectively, compared to the NPs free immobilized cells (41.9%). The optimum concentration of Fe₃O₄ NPs (10mg/mL) had both inhibitory and accelerating effects on paclitaxel degradation depending on the incubation time and temperature. Increasing dose of Fe₃O₄ NPs could increase paclitaxel degradation, despite increasing of thermodynamic inhibitory factors, only when longer time and higher temperature were used. ΔG values increased about 11.2 KJ/mol at all temperatures of 285, 295 and 305K, and ΔH increased 54.4%, in comparison with the treatment without NPs. This indicates that, inclusion of Fe₃O₄ NPs into the immobilization gels can increase the local concentration of Paclitaxel (with OH₂⁺ groups) and bacterial accessibility to the substrate and thus enhance biodegradation efficiency.

Immobilized Lignin Peroxidase-Like Metalloporphyrins as Reusable Catalysts in Oxidative Bleaching of Industrial Dyes

Synthetic and bioinspired metalloporphyrins are a class of redox-active catalysts able to emulate several enzymes such as cytochromes P450, ligninolytic peroxidases, and peroxygenases. Their ability to perform oxidation and degradation of recalcitrant compounds, including aliphatic hydrocarbons, phenolic and non-phenolic aromatic compounds, sulfides, and nitroso-compounds, has been deeply investigated. Such a broad substrate specificity has suggested their use also in the bleaching of textile plant wastewaters. In fact, industrial dyes belong to very different chemical classes, being their effective and inexpensive oxidation an important challenge from both economic and environmental perspective. Accordingly, we review here the most widespread synthetic metalloporphyrins, and the most promising formulations for large-scale applications. In particular, we focus on the most convenient approaches for immobilization to conceive economical affordable processes. Then, the molecular routes of catalysis and the reported substrate specificity on the treatment of the most diffused textile dyes are encompassed, including the use of redox mediators and the comparison with the most common biological and enzymatic alternative, in order to depict an updated picture of a very promising field for large-scale applications.

Removal of phenol in phenolic resin wastewater by a novel biomaterial: the Phanerochaete chrysosporium pellet containing chlamydospore-like cells

A novel biomaterial, the Phanerochaete chrysosporium pellet (CP) composed of chlamydospore-like cells (CLCs), was prepared and its potential in treating phenolic resin wastewater was evaluated. CP possesses higher phenol removal ability in contrast with mycelial pellets of P. chrysosporium, and CLC can be seen as the naturally immobilized enzymes. At shake-flask level, the ideal pH value, temperature, and inoculation quantity of CP for treatment of 1430 mg/l phenol wastewater were pH 4-6, 30 °C, and 5.0 g/l, respectively, and the maximum specific removal rate, 41.1 mg phenol/g CP/h, was obtained in fixed bed reactor (FBR) when the flow rate of wastewater was 3.4 l/h. During the treatment, FBR harbored amounts of bacteria (135 genera) and eukaryotes, as analyzed by metagenomic sequencing. Bacterial pollution not only decreased reactor performance but also had a negative impact on reusability of CP. Hot water treatment (80-85 °C) is effective to inhibit bacterial pollution, and heat resistance of CLC makes the repeated regrowing of CP be feasible. This work presents an innovative and low-cost biomaterial for phenol removal and will be helpful for the practical application of P. chrysosporium in wastewater treatment.

Reversible immobilization of laccase onto metal-ion-chelated magnetic microspheres for bisphenol A removal

Increasing attention has been given to nanobiocatalysis for commercial applications. In this study, laccase was reversibly immobilized onto Cu(ΙΙ)- and Mn(ΙΙ)-chelated magnetic microspheres and successfully applied to remove bisphenol A (BPA) from water. The results indicated that the loading of laccase onto the metal-ion-chelated magnetic microspheres was approximately 100mg/g. After five successive adsorption-desorption cycles, the laccase adsorption capacities did not change. In comparison with free laccase, the thermal and storage stabilities of immobilized laccase were significantly improved. Immobilized laccase exhibited a high removal efficiency for BPA under the combined actions of biodegradation and adsorption. Greater than 85% of BPA was removed under optimum conditions. The effects of various factors on the BPA removal efficiency of immobilized laccase were analysed. The results showed that metal-ion-chelated magnetic microspheres have great potential for industrial applications.

Laccase immobilized manganese ferrite nanoparticle: synthesis and LSSVM intelligent modeling of decolorization

Laccase was immobilized onto manganese ferrite nanoparticle (MFN) and dye decolorization from single and binary systems was studied. The characteristics of laccase immobilized manganese ferrite nanoparticle (LIMFN) were investigated using Fourier transform infrared (FTIR) and scanning electron microscopy (SEM). Direct red 31 (DR31), Acid blue 92 (AB92) and Direct green 6 (DG6) were used. A least square support vector machine (LSSVM) was developed to predict the decolorization efficiency of various single and binary systems based on the obtained laboratory data under different experimental conditions. Statistical and graphical quality measures were also employed to evaluate the performance and accuracy of the developed intelligent models. It is shown that the predictions of the designed LSSVM models are in close agreement with the experimental data. The effects of LIMFN dosage, pH and dye concentration on dye decolorization from single and binary systems were evaluated. Decolorization kinetics followed Michaelis-Menten Model.