Showing papers on "Immobilized enzyme published in 2021"

Rhus vernicifera Laccase Immobilization on Magnetic Nanoparticles to Improve Stability and Its Potential Application in Bisphenol A Degradation

Abstract: In the present study, Rhus vernicifera laccase (RvLac) was immobilized through covalent methods on the magnetic nanoparticles. Fe2O3 and Fe3O4 nanoparticles activated by 3-aminopropyltriethoxysilane followed with glutaraldehyde showed maximum immobilization yields and relative activity up to 81.4 and 84.3% at optimum incubation and pH of 18 h and 5.8, respectively. The maximum RvLac loading of 156 mg/g of support was recorded on Fe2O3 nanoparticles. A higher optimum pH and temperature of 4.0 and 45 °C were noted for immobilized enzyme compared to values of 3.5 and 40 °C for free form, respectively. Immobilized RvLac exhibited better relative activity profiles at various pH and temperature ranges. The immobilized enzyme showed up to 16-fold improvement in the thermal stability, when incubated at 60 °C, and retained up to 82.9% of residual activity after ten cycles of reuses. Immobilized RvLac exhibited up to 1.9-fold higher bisphenol A degradation efficiency potential over free enzyme. Previous reports have demonstrated the immobilization of RvLac on non-magnetic supports. This study has demonstrated that immobilization of RvLac on magnetic nanoparticles is very efficient especially for achieving high loading, better pH and temperature profiles, and thermal- and solvents-stability, high reusability, and higher degradation of bisphenol A.

Immobilization of carbonic anhydrase for CO2 capture and its industrial implementation: A review

Abstract: Minimal cost per ton of captured CO2 and associated environmental impacts are considerable barriers for the industrial implementation of post-combustion CO2 capture. Aqueous solvents promoted with the enzyme carbonic anhydrase are a promising alternative to replace energy intensive and environmentally unfriendly amine-based solutions, which are currently benchmark solvents in CO2 absorption. However, using free enzyme in solution requires significant amounts of enzyme in addition to its possible denaturalization. Enzyme immobilization appears as a rational approach to develop a novel CO2 capture system using aqueous solvents. In the recent literature, efforts are focused on the development and characterization of different carriers and immobilization strategies to achieve good activity and stability compared to free enzyme in solution. In the laboratory and the industry, immobilized carbonic anhydrase have been already tested in a variety of configurations including packed columns, gas-liquid membrane contactors, dynamic devices and selective membranes. This article reviews the developments, opportunities and limitations found at laboratory scale as well as in the industry, and brings them together in order to identify the key challenges and perspectives in the industrial implementation of immobilized carbonic anhydrase for CO2 capture.

Microbial L-asparaginase for Application in Acrylamide Mitigation from Food: Current Research Status and Future Perspectives.

Abstract: L-asparaginase (E.C.3.5.1.1) hydrolyzes L-asparagine to L-aspartic acid and ammonia, which has been widely applied in the pharmaceutical and food industries. Microbes have advantages for L-asparaginase production, and there are several commercially available forms of L-asparaginase, all of which are derived from microbes. Generally, L-asparaginase has an optimum pH range of 5.0–9.0 and an optimum temperature of between 30 and 60 °C. However, the optimum temperature of L-asparaginase from hyperthermophilic archaea is considerable higher (between 85 and 100 °C). The native properties of the enzymes can be enhanced by using immobilization techniques. The stability and recyclability of immobilized enzymes makes them more suitable for food applications. This current work describes the classification, catalytic mechanism, production, purification, and immobilization of microbial L-asparaginase, focusing on its application as an effective reducer of acrylamide in fried potato products, bakery products, and coffee. This highlights the prospects of cost-effective L-asparaginase, thermostable L-asparaginase, and immobilized L-asparaginase as good candidates for food application in the future.

Enzyme immobilization as a strategy towards efficient and sustainable lignocellulosic biomass conversion into chemicals and biofuels: current status and perspectives

Abstract: Environmental issues have led to the urgent necessity of research to focus on fossil fuel dependency detachment in the near future. Under the biorefinery concept, enzymatic hydrolysis is a key bioprocess for lignocellulosic biomass conversion into biofuels and bioproducts. Even though taking place under milder conditions and without the use of hazardous chemicals compared, for example, with acid hydrolysis, the use of enzymes significantly increases the cost of the process. In this sense, enzyme immobilization has emerged as an important strategy to reduce enzyme costs as it often enhances enzyme stability, while also allowing an easy recovery and reuse. This review discusses the advantages and limitations of hydrolytic lignocellulosic enzyme immobilization, with special focus on the hydrolysis of different lignocellulosic biomasses. Enzyme immobilization is a very well-studied topic, however, there is a lack of studies on the enzymatic hydrolysis of real LCM substrates and the enzyme–substrate (biomass) interactions, thus limiting the knowledge transition for the implementation of this strategy within the context of second generation biorefineries. As such, this state-of the-art compiles recent studies reporting the use of immobilized lignocellulosic enzymes and contributes to shed light on the main knowledge gaps and specific hurdles of these processes, in order to be able to take full advantage of the benefits of enzyme immobilization and boost the feasibility and attractiveness of biorefineries.

One-pot green synthesis of iron oxide nanoparticles from Bauhinia tomentosa: Characterization and application towards synthesis of 1, 3 diolein.

Abstract: The green synthesis of NPs through plant extracts can be a modest, one-pot alternative synthesis to the conventional physical or chemical method. The prime focus of this study is to produce MNPs by the reducing effect of Bauhinia tomentosa leaf extract, and it was immobilized in porcine pancreatic lipase (PPL). Synthesized NPs were characterized by field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD) and Raman spectroscopy, UV–Vis Spectrometry, Thermogravimetry, and Differential Scanning Calorimeter (DSC), Zeta potential test, VSM, BET and Fourier Transform Infrared Spectroscopy (FTIR). The effect of process parameters was studied, about the efficiency of immobilization are enzyme stability, the extent of enzyme reusability, its separation from products, the activity of immobilized enzyme, recovery, and its loss. Finally, the immobilized lipase was used for the synthesis of 1,3-diolein using enzyme-mediated esterification of oleic acid and glycerol. Under optimized condition (reaction temp-55 $$^\circ $$ C; molar ratio-2.5:1; pH-7) diolein yield was achieved to be 94%. Therefore, this work was further used for the industrial production of 1,3-diacylglycerol since a perfect enzyme-catalyzed process was observed.

Characterization of magnetic nanoparticle–immobilized cellulases for enzymatic saccharification of rice straw

Abstract: Cellulases convert lignocellulosic biomass into fermentable sugars which further act as substrate for ethanol production. Our previous research was focused on enzymatic hydrolysis of rice straw by free cellulases for production of fermentable sugars. Immobilization is a powerful tool to increase the stability and reusability of cellulases besides improving the economy of ethanol production process from rice straw. In the present study, cellulase produced from Aspergillus fumigatus was immobilized on magnetic nanoparticles by using glutaraldehyde cross linker with a binding efficiency of 65.55%. The electron microscopy and spectroscopy tools confirmed the enzyme immobilization process on magnetic nanoparticles. The immobilized cellulase exhibited filter paper, carboxymethyl cellulase and cellobiase activities of 11.82, 21.36 and 10.81 IU, respectively. The free and immobilized cellulase exhibited identical pH optima (pH 5.0) while different temperature optima of 50 °C and 60 °C, respectively. The immobilized enzyme retained 56.87% of its maximal activity after 6 h of pre-incubation at 60 °C. Km (Michaelis constant) and Vmax (maximum velocity) of immobilized enzyme were 11.76 mM and 1.17 μmol min−1 ml−1, respectively. The immobilized cellulase hydrolysed pre-treated rice straw with saccharification efficiency of 52.67%. Further, it could be reutilized for up to four saccharification cycles with retention of 50.34% activity. Therefore, the improved properties of magnetic nanoparticle-immobilized cellulase and its reusability benefits offer a promising potential for industrial production of fermentable sugars and ethanol from rice straw.

Immobilizing Enzymes on Noble Metal Hydrogel Nanozymes with Synergistically Enhanced Peroxidase Activity for Ultrasensitive Immunoassays by Cascade Signal Amplification.

Abstract: Enzyme immobilization plays an essential role in solving the problems of the inherently fragile nature of enzymes. Although prominent stability and reuse of enzymes can be achieved by enzyme immobilization, their bioactivity and catalytic efficiency will be adversely affected. Herein, PdCu hydrogel nanozymes with a hierarchically porous structure were used to immobilize horseradish peroxidase (HRP) to obtain PdCu@HRP. In addition to the improvement of stability and reusability, PdCu@HRP displayed synergistically enhanced activities than native HRP and PdCu hydrogels. Not only the specific interactions between PdCu hydrogel nanozymes and enzymes but also the enrichment of substrates around enzymes by electrostatic adsorption of hydrogels was proposed to expound the enhanced catalytic activity. Accordingly, by taking advantage of the excellent catalytic performance of the PdCu@HRP and the glucose oxidase encapsulated in zeolitic imidazolate framework-8, colorimetric biosensing of the carcinoembryonic antigen via catalytic cascade reactions for achieving signal amplification was performed. The obtained biosensor enhanced the detection sensitivity by approximately 6.1-fold as compared to the conventional HRP-based enzyme-linked immunosorbent assay, demonstrating the promising potential in clinical diagnosis.

Ultra-Thin 2D CuO Nanosheet for HRP Immobilization Supported by Encapsulation in a Polymer Matrix: Characterization and Dye Degradation

Abstract: Herein, we report the immobilization of horseradish peroxidase (HRP) on a novel two-dimensional copper oxide nanosheet (CuONS) and supported by encapsulation in poly (methyl methacrylate) (PMMA). The morphological/chemical properties of the immobilized HRP on CuONS-PMMA were investigated and characterized by scanning electron microscopy, and Fourier transforms infrared spectroscopy. After optimizing the immobilization conditions, recovered HRP activity was 72.8% using 1% CuONS–PMMA. Reusing the immobilized enzyme for ten cycles indicated that 52% of its initial activity was retained. Moreover, the immobilization of HRP using this method led to a shift in its optimum pH from 7 to broad optimum 7–7.5 and optimum temperature from 40 °C to broad optimum 40–50 °C. Km values of free and immobilized HRP were 30 and 46.7 mM for guaiacol and 5.53 and 8.55 mM for H2O2, respectively. The immobilized HRP enzyme was more stable towards metal ions. The immobilized HRP was used for crystal violet, methyl green, and malachite green dyes degradation. The immobilized HRP showed significant improvement in the capacity for dye decolorization relative to free enzyme. Therefore, based on all the characteristics mentioned above, it may be suggested that the use of this technique for HRP immobilization appears to be promising for industrial applications. A schematic illustration of the immobilization process of HRP on CuONS/PMMA.

Production of biodiesel from waste bio-oil through ultrasound assisted transesterification using immobilized lipase

Abstract: In this study, process intensification was carried out using lipase catalyzed transesterification of waste cottonseed oil (WCSO) with ethanol in the presence of ultrasonication. A maximum conversion of 98.7% was observed for ultrasound assisted transesterification. The optimum process conditions were ethanol to oil molar ratio of 4.5:1, a reaction temperature of 45°C, enzyme loading of 5 wt%, a reaction time of 6 h, ultrasonic amplitude of 40% and the duty cycle of 15 s ON and 15 s OFF. The influence of ultrasound makes the process efficient because of an effective reduction in reaction time to 6 h with the least catalyst dosage and power consumption. Reusability tests of the catalyst were conducted after separating the immobilized Rhizopus oryzae lipase. The regenerated lipase catalyst was found to have better reusability up to the fourth cycle and the produced biodiesel was within the ASTM D6751 standard. Furthermore, the ultrasound assisted process under mild operating conditions did not affect the immobilized enzyme. It was clearly observed that ultrasonication is faster and effective for biodiesel conversion using the immobilized lipase catalyzed transesterification reactions.

Enhanced Wastewater Treatment by Immobilized Enzymes

Abstract: In the presented review, we have summarized recent achievements on the use of immobilized oxidoreductases for biodegradation of hazardous organic pollutants including mainly dyes, pharmaceuticals, phenols, and bisphenols. In order to facilitate process optimization and achievement of high removal rates, effect of various process conditions on biodegradation has been highlighted and discussed. Current reports clearly show that immobilized oxidoreductases are capable of efficient conversion of organic pollutants, usually reaching over 90% of removal rate. Further, immobilized enzymes showed great recyclability potential, allowing their reuse in numerous of catalytic cycles. Collected data clearly indicates immobilized oxidoreductases as an efficient biocatalytic tools for removal of hazardous phenolic compounds, making them a promising option for future water purification. Data shows, however, that both immobilization and biodegradation conditions affect conversion efficiency; therefore, process optimization is required to achieve high removal rates. Nevertheless, we have demonstrated future trends and highlighted several issues that have to be solved in the near-future research, to facilitate large-scale application of the immobilized oxidoreductases in wastewater treatment.