Co-immobilization of glucose oxidase and catalase in silica inverse opals for glucose removal from commercial isomaltooligosaccharide

Biomimetic construction of multi-enzyme reactor through artificial antibody-antigen-directed immobilization for cascade catalytic conversion of cellulose to gluconic acid

To achieve the biotransformation of cellulose into gluconic acid, a multi-enzyme reactor comprising cellulase, glucose oxidase, and catalase was constructed through artificial antibody-antigen-directed immobilization. Catechol was used as a template to prepare artificial antibodies, which were then used to modify the enzymes through a Schiff base reaction to form artificial antigens. The artificial antibody and antigen were subsequently assembled via affinity recognition to immobilize the enzymes. The immobilization yields for all three enzymes exceeded 85 %, with specific activities of 43.48 ± 1.54 U/mg, 0.88 ± 0.06 U/mg, and 18.47 ± 1.43 U/mg, respectively. The immobilized enzymes demonstrated excellent adaptability, storage stability, reusability, and regenerability. Through the modular assembly of artificial antigen-antibody, the multi-enzyme reactor facilitated the cascade conversion of cellulose to gluconic acid.

Biomimetic co-immobilization of β-glucosidase, glucose oxidase, and horseradish peroxidase to construct a multi-enzyme biosensor for determination of amygdalin

Accurate, specific, and cost-effective detection of toxic cyanogenic glycosides is crucial for ensuring biological health and food safety. In this study, a novel biosensor based on co-immobilized multi-enzyme system was constructed by artificial antibody-antigen-directed immobilization for the colorimetric detection of amygdalin through a cascade reaction catalyzed by β-glucosidase, glucose oxidase, and horseradish peroxidase. Artificial antibodies and antigens were prepared using catechol and 3,4-dihydroxybenzaldehyde, respectively, to generate mutual affinity recognition ability for enzyme immobilization. On this basis, the biosensing system showed a complete response to amygdalin within 4 min, with a linear range from 2 to 10 μM, a detection limit of 0.18 μM, and a quantification limit of 0.6 μM. In addition, this sensor had good precision, reproducibility, stability, and reusability. This study proposed a method for detecting cyanogenic glycosides, providing a successful case for the application of cascade biosensors in food safety detection.

Magnetic Nanoparticle Support with an Ultra-Thin Chitosan Layer Preserves the Catalytic Activity of the Immobilized Glucose Oxidase

Here, we developed magnetically recoverable biocatalysts based on magnetite nanoparticles coated with an ultra-thin layer (about 0.9 nm) of chitosan (CS) ionically cross-linked by sodium tripolyphosphate (TPP). Excessive CS amounts were removed by multiple washings combined with magnetic separation. Glucose oxidase (GOx) was attached to the magnetic support via the interaction with N-hydroxysuccinimide (NHS) in the presence of carbodiimide (EDC) leading to a covalent amide bond. These steps result in the formation of the biocatalyst for D-glucose oxidation to D-gluconic acid to be used in the preparation of pharmaceuticals due to the benign character of the biocatalyst components. To choose the catalyst with the best catalytic performance, the amounts of CS, TPP, NHS, EDC, and GOx were varied. The optimal biocatalyst allowed for 100% relative catalytic activity. The immobilization of GOx and the magnetic character of the support prevents GOx and biocatalyst loss and allows for repeated use.

Evaluation of the operational conditions of the glucose oxidase and catalase multienzymatic system through enzyme co-immobilization on amino hierarchical porous silica

Hexaric acids have attracted attention lately because they are platform chemicals for synthesizing pharmaceuticals. In particular, gluconic acid is one of the most studied because it is readily available in nature. In this work, operational conditions like temperature and pH were evaluated for the enzymatic production of gluconic acid. For this purpose, glucose oxidase (GOx) and catalase (CAT) were individually immobilized and co-immobilized using amino-silica as support. The catalytic performance of the enzymes both as separate biocatalysts (GOx or CAT) and as an enzymatic complex (GOx-CAT) was assessed in terms of enzymatic activity and stability at temperatures 45 °C and 50 °C and pH 6 to 8. The results show that CAT is a key enzyme for gluconic acid production as it prevents GOx from being inhibited by H2O2. However, CAT was found to be less stable than GOx. Therefore, different GOx to CAT enzymatic ratios were studied, and a ratio of 1-3 was determined to be the best. The highest glucose conversion conditions were 45 °C and pH 7.0 for 24 h. Regarding the biocatalyst reuse, GOx-CAT retained more than 70% of its activity after 6 reaction cycles. These results contribute to further knowledge and application of oxidases for hexaric acid production and shed greater light on the role of the glucose oxidase/catalase pair in better catalytic performance. Both enzymes were immobilized in one pot, which is relevant for their potential use in industry; an enzyme system was obtained in a single step.

Effective synthesis of high-content fructooligosaccharides in engineered Aspergillus niger

BACKGROUND

Aspergillus niger ATCC 20611 is an industrially important fructooligosaccharides (FOS) producer since it produces the β-fructofuranosidase with superior transglycosylation activity, which is responsible for the conversion of sucrose to FOS accompanied by the by-product (glucose) generation. This study aims to consume glucose to enhance the content of FOS by heterologously expressing glucose oxidase and peroxidase in engineered A. niger.

RESULTS

Glucose oxidase was successfully expressed and co-localized with β-fructofuranosidase in mycelia. These mycelia were applied to synthesis of FOS, which possessed an increased purity of 60.63% from 52.07%. Furthermore, peroxidase was expressed in A. niger and reached 7.70 U/g, which could remove the potential inhibitor of glucose oxidase to facilitate the FOS synthesis. Finally, the glucose oxidase-expressing strain and the peroxidase-expressing strain were jointly used to synthesize FOS, which content achieved 71.00%.

CONCLUSIONS

This strategy allows for obtaining high-content FOS by the multiple enzymes expressed in the industrial fungus, avoiding additional purification processes used in the production of oligosaccharides. This study not only facilitated the high-purity FOS synthesis, but also demonstrated the potential of A. niger ATCC 20611 as an enzyme-producing cell factory.

Construction of co-immobilized multienzyme systems using DNA-directed immobilization technology and multifunctionalized nanoparticles

The multienzyme co-immobilization systems with high cascade catalytic efficiency and selectivity have attracted considerable attention. In this study, through DNA-directed immobilization (DDI) technology, two model enzymes, glucose oxidase (GOD) and horseradish peroxide (HRP) were co-immobilized on the multifunctional silica nanoparticles (DDI enzyme). In addition to the directional distribution promoted by DNA complementary chains, the multienzyme system allowed the control of the stoichiometric ratio of the enzymes by adjusting the ratio of amino/carboxyl groups. The optimal mole ratio of GOD/HRP was 1:2, while the protein loading amount could reach 8.06 mg·g-1. Compared with the conventional direct adsorption, the catalytic activity of the DDI enzyme was 2.49 times higher. Moreover, with the enhancement of thermal and mechanical stability, the DDI enzyme could still retain at least 50% of its initial activity after 12 cycles. Accompanied by an excellent response and good selectivity, the constructed multienzyme systems simultaneously showed the potential as a glucose detector. Therefore, based on the DDI technology, the highly efficient multienzyme co-immobilization system could be further extended for a wider range of research fields.

Nanostructured supports for multienzyme co-immobilization for biotechnological applications: Achievements, challenges and prospects

The synergistic combination of current biotechnological and nanotechnological research has turned to multienzyme co-immobilization as a promising concept to design biocatalysis engineering. It has also intensified the development and deployment of multipurpose biocatalysts, for instance, multienzyme co-immobilized constructs, via biocatalysis/protein engineering to scale-up and fulfil the ever-increasing industrial demands. Considering the characteristic features of both the loaded multienzymes and nanostructure carriers, i.e., selectivity, specificity, stability, resistivity, induce activity, reaction efficacy, multi-usability, high catalytic turnover, optimal yield, ease in recovery, and cost-effectiveness, multienzyme-based green biocatalysts have become a powerful norm in biocatalysis/protein engineering sectors. In this context, the current state-of-the-art in enzyme engineering with a synergistic combination of nanotechnology, at large, and nanomaterials, in particular, are significantly contributing and providing robust tools to engineer and/or tailor enzymes to fulfil the growing catalytic and contemporary industrial needs. Considering the above critics and unique structural, physicochemical, and functional attributes, herein, we spotlight important aspects spanning across prospective nano-carriers for multienzyme co-immobilization. Further, this work comprehensively discuss the current advances in deploying multienzyme-based cascade reactions in numerous sectors, including environmental remediation and protection, drug delivery systems (DDS), biofuel cells development and energy production, bio-electroanalytical devices (biosensors), therapeutical, nutraceutical, cosmeceutical, and pharmaceutical oriented applications. In conclusion, the continuous developments in nano-assembling the multienzyme loaded co-immobilized nanostructure carriers would be a unique way that could act as a core of modern biotechnological research.

Critical Parameters in an Enzymatic Way to Obtain the Unsweet Lactose-Free Milk Using Catalase and Glucose Oxidase Co-Encapsulated into Hydrogel with Chemical Cross-Linking

The presented work involves obtaining and characterising a two-enzymatic one-pot bioreactor, including encapsulated (co-immobilised) glucose oxidase and catalase. The enzymatic capsules were applied to produce unsweet, lactose-free milk during low-temperature catalysis. Furthermore, operational conditions, like pH and aeration, were selected in the paper, which sorts out discrepancies in literature reports. All experiments were carried out at 12 °C, corresponding to milk storage and transportation temperature. Preliminary studies (for reasons of analytical accuracy) were carried out in a buffer (pH, concentration of sugars mimicking conditions in the lactose-free milk, the initial glucose concentration 27.5 g/L) verified by processes carried out in milk in the final stage of the study. The presented results showed the need for regulating pH and the aeration of the reaction mixture in the continuous mode during the process. The procedure of co-immobilisation was performed in an alginate matrix with the cross-linking of glutaraldehyde or carbodiimide while carbodiimide showed better enzymes retention inside alginate capsules. Co-encapsulated enzymes could be used for nine cycles, preserving finally about 40% of the initial activity.

Co-immobilization of glucose oxidase and catalase in porous magnetic chitosan microspheres for production of sodium gluconate

In the process of immobilizing the enzyme, the overflow of enzyme and the decrease of enzyme activity are very serious. In order to improve the stable binding between enzyme and carrier, a kind of porous magnetic chitosan microsphere with appropriate pore size was successfully prepared by adjusting the size of pore-forming agent in this paper. The rough porous structure is favorable for the adsorption of enzyme and the catalytic action of enzyme on substrate. The results showed that when the pore size of the microspheres was at 790.15 ± 250.91 nm, the protein loading and enzyme activity of GOD could be increased effectively, which could reach 58.28 ± 2.64 mg/g and 16.93 ± 0.14 U, respectively. The co-immobilization of CAT and GOD eliminated the harmful by-product H2O2 in time and effectively solved the problem of continuous deactivation of GOD in the reaction process. When the mass ratio of PMCSM/GOD/CAT was 100/6.02/10.96 (mg/mg/mg), the relative enzyme activity of GOD reached the highest (133.32 ± 0.68%). The thermal stability and pH stability of the enzyme were greatly improved after co-immobilization. The relative enzyme activity of PMCSM@GOD@CAT was 57.27 ± 3.04% at 60 °C, while that of free GOD was only 28.76 ± 4.10%. The relative enzyme activity of PMCSM@GOD@CAT was above 63% at pH 5–10, while the relative enzyme activity of free GOD was only 4.98 ± 0.72% at pH 10. The yield of sodium gluconate from 50 mL 250 mg/mL glucose catalyzed by PMCSM@GOD@CAT loading 60.2 mg GOD was 96.19 ± 0.79% at pH 6.0 and 30 °C, and the reaction lasted 6 h. The relative enzyme activity of PMCSM@GOD@CAT remained 69.77 ± 0.78% after repeated use for 10 times. After 30 days of storage, PMCSM@GOD@CAT maintained its initial activity of 76.52 ± 1.41%. The immobilized process studied in this paper provides a theoretical basis for the production of sodium gluconate by double enzyme directly catalyzing and lays a certain foundation for the application of immobilized enzyme in the future chemical industry and food industry.

A SiO2 Microcarrier with an Opal-like Structure for Cross-Linked Enzyme Immobilization

The opal-like SiO₂ microcarriers with different pore diameters named opal-SiO₂I and opal-SiO₂II were synthesized and utilized as microcarriers to immobilize Rhizopus oryzae lipase (ROL) and Aspergillus oryzae α-amylases (AOA). ROL and AOA can be more stably immobilized on the cross-linked SiO₂ opals by neopentyl glycol diglycidyl ether (NGDE), which is the first attempt to use it as a cross-linking agent compared with glutaraldehyde. According to the morphology analysis, multiple layers of SiO₂ monodisperse microspheres were regularly packed and formed an opal-like structure, and enzymes were well scattered and immobilized throughout the SiO₂ opals. The results showed that the performance of enzymes immobilized on opal-SiO₂II with a larger specific surface area was much better than that of opal-SiO₂I. The enzyme activity of ROL@opal-SiO₂II and AOA@opal-SiO₂II cross-linked with 1% NGDE increased 5.32 and 9.32 times compared with their free counterpart, respectively. Furthermore, pH and thermal stability and reusability of ROL/AOA@opal-SiO₂II were significantly improved and higher than those of ROL/AOA@opal-SiO₂I and free enzymes. This study provides an easily obtained microcarrier opal-SiO₂II, which shows potential for efficient different enzyme immobilizations and further industrial applications.

Glucose Oxidase Immobilized on Magnetic Zirconia: Controlling Catalytic Performance and Stability

Here, we report the structures and properties of biocatalysts based on glucose oxidase (GOx) macromolecules immobilized on the mesoporous zirconia surface with or without magnetic iron oxide nanoparticles (IONPs) in zirconia pores. Properties of these biocatalysts were studied in oxidation of d-glucose to d-gluconic acid at a wide range of pH and temperatures. We demonstrate that the calcination temperature (300, 400, or 600 °C) of zirconia determines its structure, with crystalline materials obtained at 400 and 600 °C. This, in turn, influences the catalytic behavior of immobilized GOx, which was tentatively assigned to the preservation of GOx conformation on the crystalline support surface. IONPs significantly enhance the biocatalyst activity due to synergy with the enzyme. At the same time, neither support porosity nor acidity/basicity shows correlations with the properties of this biocatalyst. The highest relative activity of 98% (of native GOx) at a pH 6-7 and temperature of 40-45 °C was achieved for the biocatalyst based on ZrO₂ calcined at 600 °C and containing IONPs. This process is green as it is characterized by a high atom economy due to the formation of a single product with high selectivity and conversion and minimization of waste due to magnetic separation of the catalyst from an aqueous solution. These and an exceptional stability of this catalyst in 10 consecutive reactions (7% relative activity loss) make it favorable for practical applications.

Efficient Multi-Enzymes Immobilized on Porous Microspheres for Producing Inositol From Starch

In vitro synthetic enzymatic biosystem is considered to be the next generation of biomanufacturing platform. This biosystem contains multiple enzymes for the implementation of complicated biotransformatiom. However, the hard-to-reuse and instability of multiple enzymes limit the utilization of this biosystem in industrial process. Multi-enzyme immobilization might be a feasible alternative to address these problems. Herein, porous microspheres are used as carriers to co-immobilize multiple enzymes for producing inositol from starch. At first, all the enzymes (i.e., α-glucan phosphorylase aGP, phosphoglucose mutase PGM, inositol 1-phosphate synthase IPS, and inositol monophosphatase IMP) for converting starch to inositol were immobilized on porous microspheres individually to check the effect of immobilization, then all the enzymes are co-immobilized on porous microspheres. Compared to reaction system containing all the individual immobilized enzymes, the reaction system containing the co-immobilized enzymes exhibit ∼3.5 fold of reaction rate on producing inositol from starch. This reaction rate is comparable to that by free enzyme mixture. And the co-immobilized multi-enzyme system show higher thermal stability and recovery stability than free enzyme mixture. After 7 batches, the immobilized enzymes retain 45.6% relative yield, while the free enzyme mixture only retain 13.3% relative yield after 3 batches. Co-immobilization of multiple enzymes on porous microspheres for biomanufacturing would shed light on the application of in vitro synthetic enzymatic biosystem in industrial scale.

Removal of Small-Molecular Byproducts from Crude Fructo-Oligosaccharide Preparations by Fermentation Using the Endospore-Forming Probiotic Bacillus coagulans

Short-chain prebiotic fructo-oligosaccharides (FOS) produced by enzymatic conversion from sucrose often contains high concentration of monosaccharides as byproducts. In addition to conventional physical/chemical purification processes, microbial treatment is an alternative method to remove these byproducts. We used Bacillus coagulans to reduce the abundance of byproducts during the enzymatic production of FOS. It is a promising probiotic because this thermophilic and spore-forming bacterium remains viable and stable during food processing and storage. B. coagulans also produces lactic acid during the carbohydrate metabolism and is used industrially to produce lactic acid for medical and food/feed applications. We aimed to establish an evaluation system to screen different strains of B. coagulans for their performance and selected B. coagulans Thorne for the treatment of crude FOS due to its high growth rate, high sporulation rate, and low nutrient requirements. B. coagulans preferentially utilized monosaccharides over other sugar components of the FOS mixture. Glucose and fructose were completely consumed during the fermentation but 85% (w/w) of the total FOS remained. At the end of the fermentation, the total viable cell count of B. coagulans Thorne was 9.9 × 108 cfu·mL−1 and the maximum endospore count was 2.42 × 104 cfu·mL−1.

Enzyme production ofd-gluconic acid and glucose oxidase: successful tales of cascade reactions

This review mainly focuses on the use of glucose oxidase in the production ofd-gluconic acid, which is a reactant of undoubtable interest in different industrial areas. As example of diverse enzymatic cascade reactions.

Combi-CLEAs of Glucose Oxidase and Catalase for Conversion of Glucose to Gluconic Acid Eliminating the Hydrogen Peroxide to Maintain Enzyme Activity in a Bubble Column Reactor

In this study combined cross-linked aggregates of catalase from bovine liver and glucose-oxidase from Aspergillus niger were prepared, and the effects of the precipitant and crosslinking agents, as well as the use of bovine serum albumin (BSA) as a feeder protein, on enzyme immobilization yield and thermal stability of both enzymes, were evaluated. Combi- crosslinking of enzyme aggregates (CLEAs) prepared using dimethoxyethane as precipitant, 25 mM glutaraldehyde and BSA/enzymes mass ratio of 5.45 (w/w), exhibited the highest enzyme activities and stabilities at 40 °C, pH 6.0, and 250 rpm for 5 h. The stability of both immobilized enzymes was fairly similar, eliminating one of the problems of enzyme coimmobilization. Combi-CLEAs were used in gluconic acid (GA) production in a bubble column reactor operated at 40 °C, pH 6.0 and 10 vvm of aeration, using 26 g L−1 glucose as the substrate. Results showed conversion of around 96% and a reaction course very similar to the same process using free enzymes. The operational half-life was 34 h, determined from kinetic profiles and the first order inactivation model. Combi-CLEAs of glucose-oxidase and catalase were shown to be a robust biocatalyst for applications in the production of gluconic acid from glucose.

Immobilized glucose oxidase on magnetic silica and alumina: Beyond magnetic separation

Here we report immobilization of glucose oxidase (GOx) on magnetic silica (Fe₃O₄-SiO₂) and alumina (Fe₃O₄-Al₂O₃) functionalized with amino groups using glutaraldehyde as a linker. Magnetic support based biocatalysts demonstrate high catalytic activity in d-glucose oxidation to D-gluconic acid at pH 5-7.5 and temperature of 30-50 °C with the best activities of 95% and 91% for magnetic silica and alumina, respectively. A comparison of magnetic and non-magnetic alumina and silica shows a significant enhancement of the relative catalytic activity for magnetic supports, while the silica based biocatalysts show a higher activity than the biocatalysts based on alumina. A noticeably higher activity of GOx immobilized on magnetic supports is explained by synergy of the GOx inherent activity and enzyme-like activity of iron oxide nanoparticles, while the enhancement with silica based catalysts is most likely due to a larger pore size and stronger Brønsted acid sites. Excellent relative activity of Fe₃O₄-SiO₂-GOx (95% of native GOx) in a tolerant pH and temperature range as well as high stability in a repeated use (6% relative activity loss after five catalytic cycles) makes this catalyst promising for practical applications.

Co-localization of oxidase and catalase inside a porous support to improve the elimination of hydrogen peroxide: Oxidation of biogenic amines by amino oxidase from Pisum sativum

Diamine oxidase (DAO) from Pisum sativum is an enzyme that catalyzes the degradation of biogenic amines (BA) present in wine, producing harmless aldehydes and hydrogen peroxide (H2O2). H2O2 promotes a rapid inactivation of the immobilized enzyme. At first glance, co-immobilization of DAO and catalase (CAT) could improve the elimination of the released hydrogen peroxide. Two different co-immobilized derivatives were prepared: (a) both enzymes co-localized and homogeneously distributed across the whole structure of a porous support, and (b) both enzymes we de-localized inside the porous support: DAO immobilized on the outer part of the porous support and catalase immobilized in the inner part. Co-localized derivatives were seven-fold more effective than de-localized ones for the elimination of hydrogen peroxide inside the porous support. In addition to that, the degradation of putrescine by DAO was three-fold more rapid when using both co-localized enzymes. The optimal co-localized derivative (containing 1.25 mg of DAO plus 25 mg of CAT per g of support) promoted the instantaneous elimination of 91% H2O2 released inside the porous support during putrescine oxidation. This optimal derivative preserves 92% of activity after three reaction cycles and DAO immobilized without catalase only preserves 41% of activity. Co-localization seems to be the key strategy to immobilize two sequential enzymes. When enzymes are immobilized in close proximity to each other in a co-localized pattern, the generation of byproducts as H2O2 is strongly reduced.