Biocatalysts (enzymes and whole cells) catalyze reactions with the advantage of superior chemo-, regio-, and stereo-specificity in mild conditions, thereby avoiding the production of larger amounts ...of waste. The currently great practical importance of immobilized biocatalysts is expressed by the high number of scientific publications together with an ever increasing number of different applications in this area of enzyme technology. This mainly relies on new research results with respect to immobilization techniques and the development of advanced carrier materials designed for this purpose.
The employment of immobilized biocatalysts is one of the most effective and powerful tools used in the modern chemical industry as a prerequisite for an economical and environmentally friendly production process. The book presented here reflects the currently great practical importance of immobilized biocatalysts by means of a variety of actual examples. They comprise the immobilization of enzymes from different enzyme classes and a variety of whole cells with particular importance for the production of compounds for application in the chemical, pharmaceutical and food industry (in part from renewable resources), biohydrogen production, the fabrication of biosensors, and the treatment of waste water. Several articles introduce new research results with respect to immobilization techniques and the development of carrier materials designed for this purpose.
In addition, review articles provide among others an overview of the industrial application of immobilized biocatalysts in various areas including the energy sector, or discuss the many advantages of metal–organic frameworks (MOFs) as platforms for enzyme immobilization. They deal with the pros and cons of many inorganic, organic, hybrid and composite materials, including nano-supports, used for the immobilization of biocatalysts, and with the development of engineered strains applied to the conversion of lignocellulosic biomass to platform chemicals by consolidated bioprocessing.
In summary, the articles meet the state of the art of both scientific and technical standards and the book is indispensable for all those involved in the various aspects of this topic.
Developing value-added lignin-based biomaterials for enzyme immobilization has drawn great attention. This study developed a cost-effective and eco-friendly one-pot strategy to synthesize the ...rod-like lignin@zeolitic imidazolate framework-8 (ZIF-8) hybrid nanomaterial by using lignin derived from lignocellulosic biofuel production. The incorporation of lignin into the ZIF-8 network not only altered the morphology, but also modified the surface properties of the material, making it an ideal support for enzyme immobilization. The synthesized nanoscale hybrid materials were used to immobilize beta-glucosidase (BG) with high immobilization capacity and about 92–166 mg/g of BG was immobilized through physical adsorption. The immobilized BG exhibited good stability, catalytic activity and recycling properties, and was reused under acidic conditions for more than 8 cycles with more than 60% activity kept. The as-prepared hybrid material can serve as a great carrier for immobilizing various biomolecules.
•A one-pot strategy was developed to synthesize the rod-like lignin@ZIF-8.•The morphology and surface properties of lignin@ZIF-8 were characterized.•The immobilization capacity of lignin@ZIF-8 for beta-glucosidase (BG) was about 92–166 mg/g.•The relative activity of immobilized BG was more than 60% after 8 times reuse.
Transaminases have attracted considerable interest in their use as biocatalysts for the synthesis of compounds containing chiral amine units, which are widespread within the pharmaceutical, ...agrochemical, and fine chemical industry. Recent developments in enzyme- and process-engineering have expedited their use in asymmetric synthesis; however, industrial applications are still hindered by a number of factors, including equilibrium thermodynamics, product inhibition, and poor substrate tolerance. Detailed and comprehensive approaches to each of these challenges have been reported during the last two decades; the most representative enzyme discovery and screening strategies, protein and equilibrium engineering, and immobilization techniques are reviewed herein. Furthermore, we present a detailed look into the applications of transaminases for the synthesis of a variety of amine-containing compounds and the integration of transaminases into multienzymatic systems that allow access to a variety of highly complex products for the end user.
•A novel photon-enzyme cascade system was constructed through self-assembly.•Biocatalytic nanoflower has high HRP loading and improved activity.•The hybrid nanoflowers showed excellent degradation ...performance for BPA.•The HRP-CN/Cu3(PO4)2 can be an alternative to GOx&HRP cascade catalysis system.
Inspired by the multi-enzymes cascade catalysis, a novel photon-enzyme cascade catalysis system described as hybrid HRP-CN/Cu3(PO4)2 nanoflowers was constructed successfully for the first time. It not only exhibits excellent immobilized enzyme enzymatic properties but also has better tolerance to extreme acid, alkali and high temperature compared with the free HRP. Moreover, the encapsulation yield of HRP reaches up to 36.2% and the residual activity after 5 cycles still has 83.6% over HRP-CN/Cu3(PO4)2 catalyst. Specifically, the HRP-CN/Cu3(PO4)2 showed excellent degradation performance for bisphenol A (BPA), which reached up to 72.98% far more than that of CN/Cu3(PO4)2 (41.89%) and HRP/Cu3(PO4)2 (4.71%). Those unique advantages are mainly owing to the introduction of photocatalyst (g-C3N4), which not only increases the encapsulation yield of HRP, but also realizes the complete mineralization of BPA. The photon-enzyme cascade catalysis system could replace the traditional system composed of glucose oxidase and horseradish peroxidase (GOx&HRP) for the harmless treatment of BPA, providing a new strategy for HRP in wastewater treatment.
The widespread occurrence and adverse environmental and health-related impacts of various types of emerging contaminants (ECs) have become an issue of high concern. With ever increasing scientific ...knowledge, socio-economic awareness, health-related problems and ecological apprehensions, people are more concerned about the widespread ECs, around the globe. Among ECs, biologically active compounds from pharmaceutical, cosmeceutical, biomedical, personal care products (PPCPs), endocrine-disrupting chemicals (EDCs), and flame-retardants are of paramount concern. The presence and persistence of ECs in water bodies are of continued and burning interest, worldwide. Various types of ECs are being discharged knowingly/unknowingly with/without partial treatments into the aquatic environments that pose serious health issues and affects the entire living ecosystem. So far, various approaches have been developed for ECs degradation and removal to diminish their adverse impact. Many previous and/or ongoing studies have focused on contaminants degradation and efficient removal via numerous treatment strategies, i.e. (1) physical, (2) chemical and (3) biological. However, the experimental evidence is lacking to enable specific predictions about ECs mechanistic degradation and removal fate across various in-practice systems. In this context, the deployment oxidoreductases such as peroxidases (lignin peroxidases, manganese-dependent peroxidases, and horseradish peroxidase), aromatic dioxygenases, various oxygenases, laccases, and tyrosinases have received considerable research attention. Immobilization is highlighted as a promising approach to improve enzyme catalytic performance and stabilization, as well as, to protect the three-dimensional structure of the enzyme against the undesirable consequences of harsh reaction environment. This work overviews the current and state-of-the-art critical aspect related to hazardous pollutants at large and ECs in particular by the immobilized oxidoreductase enzymes. The first part of the review focuses on the occurrence, physiochemical behavior, potent sources and significant routes of ECs. Following that, environmentally-related adverse impacts and health-related issues of ECs are discussed in the second part. In the third part, biodegradation and removal strategies with a comparative overview of several conventional vs. non-conventional methods are presented briefly. The fourth part majorly focuses on operational modes of different oxidoreductase enzyme-based biocatalytic processes for the biodegradation and biotransformation of a wide array of harmful environmental contaminants. Finally, the left behind research gaps, concluding remarks as well as future trends and recommendations in the use of carrier-immobilized oxidoreductases for environmental perspective are also discussed.
•This review deals with the removal of emerging contaminants (ECs) by immobilized oxidoreductases.•Occurrence, physicochemical behavior, potent sources and significant routes of ECs are discussed.•Environmentally-related adverse impacts and health-related issues of ECs are discussed.
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•Laccase was steadily immobilized in a metal-organic framework/polyvinyl alcohol (MOF/PVA) cryogel.•The immobilized laccase showed both good stability and reusability.•The removal of ...anthraquinone dye was efficient and feasible.•C-α oxidation was shown to be the dominant mechanism for alizarin green degradation.
Anthraquinones (AQs) are hard-degraded substances that can cause significant harm to the environment. Many treatment methods are under consideration, among which biodegradation by laccase is competitive. AQs can be degraded by laccase, but the mechanism is indistinct, and the free laccase lacks stability and reusability. In this study, an eco-friendly metal–organic framework (MOF) composite, a MOF/polyvinyl alcohol (PVA) cryogel, is synthesized to construct a MOF/PVA immobilized laccase, i.e., MOF/PVA/Lac. Among all the MOF/PVA/Lac, the MIL-68(Al)/PVA/Lac (MIL-68(Al) is one of MOFs) showed excellent enzymatic properties where the pH stability, thermal stability, and operational stability were enhanced. The MIL-68(Al)/PVA/Lac achieved a high removal efficiency (95.86%) of alizarin green within 12 h and maintained more than 60% of its activity after six reaction cycles. Using molecular docking, mass spectrometry (MS), and two-dimensional nuclear magnetic resonance (2D-NMR), the final product of the degradation process, p-toluidine, was identified. The affinity sites of laccase for alizarin green were determined, and the reaction mechanism, C-α oxidation, was confirmed.
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•Enzyme@MOF composites are still at an early stage of development.•Enzyme@MOF composites are a versatile host platform for the effective enzymes immobilization systems.•Different ...approaches and process optimization of preparing enzyme@MOF composites are evaluated.•There will be great demand on Enzyme@MOF composites with diverse functionality.
Metal-organic frameworks (MOFs) are a type of porous material that have tunable porosity, desirable functionality, extremely high surface area, and chemical/thermal stability. MOFs consist of metal containing nodes and organic ligands linked through coordination bonds. Owing to the unique properties of MOFs, there is considerable interest in using them as a potential matrix for enzyme immobilization. Recent studies have focused on developing enzyme-MOF composites with potential applications. Many MOF-enzyme composites exhibit excellent catalytic performance, far outperforming free enzymes in many aspects. This review summarizes recent developments in enzyme-MOF composites with special emphasis on novel synthesizing strategies, process optimization, and improvement of catalytic performance of the enzyme-MOF composites over free enzymes.
The persistent disposal of xenobiotic compounds like insecticides, pesticides, fertilizers, plastics and other hydrocarbon containing substances is the major source of environmental pollution which ...needs to be eliminated. Many contemporary remediation methods such as physical, chemical and biological are currently being used, but they are not sufficient to clean the environment. The enzyme based bioremediation is an easy, quick, eco-friendly and socially acceptable approach used for the bioremediation of these recalcitrant xenobiotic compounds from the natural environment. Several microbial enzymes with bioremediation capability have been isolated and characterized from different natural sources, but less production of such enzymes is a limiting their further exploitation. The genetic engineering approach has the potential to get large amount of recombinant enzymes. Along with this, enzyme immobilization techniques can boost the half-life, stability and activity of enzymes at a significant level. Recently, nanozymes may offer the potential bioremediation ability towards a broad range of pollutants. In the present review, we have described a brief overview of the microbial enzymes, different enzymes techniques (genetic engineering and immobilization of enzymes) and nanozymes involved in bioremediation of toxic, carcinogenic and hazardous environmental pollutants.
•Microbial enzymes involved in degradation of various toxic pollutants.•Major biodegrdative enzymes over-expressed using recombinant DNA technology.•Enzyme immobilization techniques increase the half-life, stability and activity of enzymes.•Nanozymes used for bioremediation purpose.
The biological activities of heparan sulfate (HS) are intimately related to their molecular weights, degree and pattern of sulfation and homogeneity. The existing methods for synthesizing homogeneous ...sugar chains of low dispersity involve multiple steps and require stepwise isolation and purification processes. Here, we designed a mesoporous metal-organic capsule for the encapsulation of glycosyltransferase and obtained a microreactor capable of enzymatically catalyzing polymerization reactions to prepare homogeneous heparosan of low dispersity, the precursor of HS and heparin. Since the sugar chain extension occurs in the pores of the microreactor, low molecular weight heparosan can be synthesized through space-restricted catalysis. Moreover, the glycosylation co-product, uridine diphosphate (UDP), can be chelated with the exposed metal sites of the metal-organic capsule, which inhibits trans-cleavage to reduce the molecular weight dispersity. This microreactor offers the advantages of efficiency, reusability, and obviates the need for stepwise isolation and purification processes. Using the synthesized heparosan, we further successfully prepared homogeneous 6-O-sulfated HS of low dispersity with a molecular weight of approximately 6 kDa and a polydispersity index (PDI) of 1.032. Notably, the HS generated exhibited minimal anticoagulant activity, and its binding affinity to fibroblast growth factor 1 was comparable to that of low molecular weight heparins.
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Immobilization is a key technology for successful realization of enzyme‐based industrial processes, particularly for production of green and sustainable energy or chemicals from biomass‐derived ...catalytic conversion. Different methods to immobilize enzymes are critically reviewed. In principle, enzymes are immobilized via three major routes (i) binding to a support, (ii) encapsulation or entrapment, or (iii) cross‐linking (carrier free). As a result, immobilizing enzymes on certain supports can enhance storage and operational stability. In addition, recent breakthroughs in nano and hybrid technology have made various materials more affordable hosts for enzyme immobilization. This review discusses different approaches to improve enzyme stability in various materials such as nanoparticles, nanofibers, mesoporous materials, sol–gel silica, and alginate‐based microspheres. The advantages of stabilized enzyme systems are from its simple separation and ease recovery for reuse, while maintaining activity and selectivity. This review also considers the latest studies conducted on different enzymes immobilized on various support materials with immense potential for biosensor, antibiotic production, food industry, biodiesel production, and bioremediation, because stabilized enzyme systems are expected to be environmental friendly, inexpensive, and easy to use for enzyme‐based industrial applications.
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