Covalent immobilization of peanut β-amylase for producing industrial nano-biocatalysts: A comparative study of kinetics, stability and reusability of the immobilized enzyme

Enzymatic interfacial conversion of acylglycerols in Pickering emulsions stabilized by hydrogel microparticles

HYPOTHESIS

A critical challenge in the enzymatic conversion of acylglycerols is the limited exposure of the enzyme dissolved in the aqueous solution to the hydrophobic substrate in the oil phase. Positioning the enzyme in a microenvironment with balanced hydrophobicity and hydrophilicity in Pickering emulsion will facilitate the acylglycerol-catalyzing reactions at the interface between the oil and liquid phases.

EXPERIMENTS

In this work, to overcome the challenge of biphasic catalysis, we report a method to immobilize enzymes in polyethylene glycol (PEG)-based hydrogel microparticles (HMPs) at the interface between the oil and water phases in Pickering emulsion to promote the enzymatic conversion of acylglycerols.

FINDINGS

3 wt% of HMPs can stabilize the oil-in-water Pickering emulsion for at least 14 days and increase the viscosity of emulsions. Lipase-HMP conjugates showed significantly higher hydrolytic activity in Pickering emulsion; HMP-immobilized lipase SMG1 showed an activity about three times that of free lipase SMG1. Co-immobilization of a lipase and a fatty acid photodecarboxylase from Chlorella variabilis (CvFAP) in Pickering emulsion enables light-driven cascade conversion of triacylglycerols to hydrocarbons, transforming waste oil to renewable biofuels in a green and sustainable approach. HMPs stabilize the Pickering emulsion and promote interfacial biocatalysis in converting acylglycerols to renewable biofuels.

Engineering and application of polysaccharides and proteins-based nanobiocatalysts in the recovery of toxic metals, phosphorous, and ammonia from wastewater: A review

Global waste production is anticipated reach to 2.59 billion tons in 2030, thus accentuating issues of environmental pollution and health security. 37 % of waste is landfilled, 33 % is discharged or burned in open areas, and only 13.5 % is recycled, which makes waste management poorly efficient in the context of the circular economy. There is therefore a need for methods to recycle waste into valuable materials through resource recovery process. Progress in the field of recycling is strongly dependent on the development of efficient, stable, and reusable, yet inexpensive catalysts. In this case, a growing attention has been paid to development and application of nanobiocatalysts with promising features. The main purpose of this review paper is to: (i) introduce nanobiomaterials and describe their effective role in the preparation of functional nanobiocatalysts for the recourse recovery aims; (ii) provide production methods and the efficiency improvement of nanobaiocatalysts; (iii) give comprehensive description of valued resource recovery for reducing toxic chemicals from the contaminated environment; (iv) describe various technologies for the valued resource recovery; (v) state the limitation of the valued resource recovery; (vi) and finally economic importance and current scenario of nanobiocatalysts strategies applicable for the resource recovery processes.

Study on the Interaction Mechanism of Methoxy Polyethylene Glycol Maleimide with Sweet Potato β-Amylase

In this study, sweet potato β-amylase (SPA) was modified by methoxy polyethylene glycol maleimide (molecular weight 5000, Mal-mPEG5000) to obtain the Mal-mPEG5000-SPA modified β-amylase and the interaction mechanism between SPA and Mal-mPEG5000 was investigated. the changes in the functional groups of different amide bands and modifications in the secondary structure of enzyme protein were analyzed using infrared spectroscopy and circular dichroism spectroscopy. The addition of Mal-mPEG5000 transformed the random curl in the SPA secondary structure into a helix structure, forming a folded structure. The Mal-mPEG5000 improved the thermal stability of SPA and protected the structure of the protein from breaking by the surrounding. The thermodynamic analysis further implied that the intermolecular forces between SPA and Mal-mPEG5000 were hydrophobic interactions and hydrogen bonds due to the positive values of ΔH^θ and ΔS^θ. Furthermore, the calorie titration data showed that the binding stoichiometry for the complexation of Mal-mPEG5000 to SPA was 1.26, and the binding constant was 1.256 × 10⁷ mol/L. The binding reaction resulted from negative enthalpy, indicating that the interaction of SPA and Mal-mPEG5000 was induced by the van der Waals force and hydrogen bonding. The UV results showed the formation of non-luminescent material during the interaction, the Fluorescence results confirmed that the mechanism between SPA and Mal-mPEG5000 was static quenching. According to the fluorescence quenching measurement, the binding constant (K_A) values were 4.65 × 10⁴ L·mol^-1 (298K), 5.56 × 10⁴ L·mol^-1 (308K), and 6.91 × 10⁴ L·mol^-1 (318K), respectively.

Biochemical Properties of β-Amylase from Red Algae and Improvement of Its Thermostability through Immobilization

β-Amylase hydrolyzes polysaccharides, such as starch, into maltose. It is used as an industrial enzyme in the production of food and pharmaceuticals. The eukaryotic red alga Cyanidioschyzon merolae is a unicellular alga that grows at an optimum pH of 2.0-3.0 and an optimum temperature of 40-50 °C. By focusing on the thermostability and acid resistance of the proteins of C. merolae, we investigated the properties of β-amylase from C. merolae (hereafter CmBAM) and explored the possibility of using CmBAM as an industrial enzyme. CmBAM showed the highest activity at 47 °C and pH 6.0. CmBAM had a relatively higher specificity for amylose as a substrate than for starch. Immobilization of CmBAM on a silica gel carrier improved storage stability and thermostability, allowing the enzyme to be reused. The optimum temperature and pH of CmBAM were comparable to those of existing β-amylases from barley and wheat. C. merolae does not use amylose, but CmBAM has a substrate specificity for both amylose and amylopectin but not for glycogen. Among the several β-amylases reported, CmBAM was unique, with a higher specificity for amylose than for starch. The high specificity of CmBAM for amylose suggests that isoamylase and pullulanase, which cleave the α-1,6 bonds of starch, may act together in vivo. Compared with several reported immobilized plant-derived β-amylases, immobilized CmBAM was comparable to β-amylase, with the highest reusability and the third-highest storage stability at 30 days of storage. In addition, immobilized CmBAM has improved thermostability by 15-20 °C, which can lead to wider applications and easier handling.

Immobilization of Urease Enzyme on Chitosan/Polyvinyl alcohol Electrospun Nanofibers

Electrospun nanofibers have gained much attention for enzyme immobilization due to their high surface-to-volume ratio. In this study, urease was immobilized on chitosan/poly (vinyl alcohol) (PVA) nanofibers by both adsorption and crosslinking methods. In order to obtain nanofibers with more desirable properties, solutions with different ratios of chitosan and PVA were electrospun and crosslinked using glutaraldehyde. Comparing SEM images of the nanofibers, before and after immersing them in phosphate buffer, it was shown that higher chitosan content leads to more stable fibers. So, the solution with the chitosan to PVA ratio of 40:60 was used for enzyme immobilization. Then, the effects of initial protein concentration, temperature, incubation time, and method of immobilization were investigated to reach the highest enzyme activity. Under similar immobilization conditions, covalently immobilized urease showed higher activity, compared to uncrosslinked immobilized enzyme. Besides, it retained 30% of its initial activity after 10 times usage. So, this method was chosen for further investigation. Not only the activity of the immobilized enzyme was much higher than the free enzyme in a wide range of pH and temperature, but also stability of the immobilized enzyme was improved. Immobilized urease was then used to remove thiourea which is a toxic compound. Findings indicated 60% hydrolysis of initial thiourea in 12 hours. In conclusion, the findings showed that chitosan/PVA nanofibers are suitable candidates for the immobilization of urease. This article is protected by copyright. All rights reserved.

Magnetic layered double hydroxide nanosheet as a biomolecular vessel for enzyme immobilization

Magnetic nanoparticle coated with manganese‑aluminum layered double hydroxide (Fe3O4/Mg-Al-CO3-LDH) was prepared and used as porous support for ficin (EC 3.4.22.3) as a model enzyme. Structural characteristics were studied by XRD, FTIR, SEM and light scattering. The quantity of immobilized ficin on the mentioned LDH and non-magnetic LDH was measured and enzyme activity, stability and reusability were compared. Results revealed that the core and shell structure of Fe₃O₄/Mg-Al-CO₃-LDH makes it better dispersion compared to the pristine Mg-Al-CO₃-LDH. Ficin showed strong affinity to absorption of the surface of mentioned LDHs nanosheet especially magnetic LDH, confirmed that the existence of Fe₃O₄ in the core structure of magnetic Fe₃O₄/Mg-Al-CO₃-LDH caused better dispersion of LDH nanocrystal shell compared to pristine LDH moreover, enzyme which immobilized on the magnetic LDH supports, can be recovered by magnetic interaction. The storage stability of free ficin, immobilized ficin on the Mg-Al-CO₃-LDH and Fe₃O₄/Mg-Al-CO₃-LDH during a period of 120 days lost about 75%, 30%, and 20% of their initial activities, respectively.

Encapsulation of peroxidase on hydrogel sodium polyacrylate spheres incorporated by silver and gold nanoparticles: A comparative study

The selectivity of biocatalysts based on enzymes, eco-friendly reaction systems, and strong catalyst performance is exceptionally compelling. For improving enzyme recyclability and stability, a good option that has been proved is immobilization. For enzyme immobilization, hydrogel sodium polyacrylate combined with nanoparticles is an interesting class of support matrices as compared to others. This study synthesizes and uses the cross-linked hydrogel sodium polyacrylate-decorated gold or silver nanoparticles (HSP/AuNPs or AgNPs) as immobilized support for peroxidase and FTIR characterizes it. The novel supports immobilized system properties enhanced biocompatibility. They have attained a greater immobilization yield (91% with HSP/AuNPs and 84% with HSP/AgNPs). The rest of the immobilized peroxidase activity, after 10 recurring cycles of HSP/AuNPs was 61% and HSP/AgNPs was 54% . The remaining activity of the immobilized enzyme onto HSP/AgNPs, after storing at 4°C for 6 weeks, was 73% and HSP/AuNPs was 75% of its initial activity. It was revealed that the optimum temperature for the free enzyme and the immobilized enzyme was 50°C and 50–60°C, respectively. For the immobilized enzyme, the optimum pH is 7–7.5, as compared to the optimum pH of free enzyme pH 6.5.

Preparation and characterization of stable core/shell Fe3O4@Au decorated with an amine group for immobilization of lipase by covalent attachment

The self-assembly approach was used for amine decoration of core/shell Fe₃O₄@Au with 4-aminothiophenol. This structure was used for covalent immobilization of lipase using a Ugi 4-component reaction. The amine group on the structure and carboxylic group from lipase can react in the Ugi reaction and a firm and stable covalent bond is created between enzyme and support. The synthesized structure was fully characterized and its activity was explored in different situations. The results showed the pH and temperature stability of immobilized lipase compared to free lipase in a wide range of pH and temperature. Also after 60 days, it showed excellent activity while residual activity for the free enzyme was only 10%. The synthesized structure was conveniently separated using an external magnetic field and reused 6 times without losing the activity of the immobilized enzyme.

The self-assembly approach was used for amine decoration of core/shell Fe₃O₄@Au with 4-aminothiophenol.

Stimuli-Responsive Regulation of Biocatalysis through Metallic Nanoparticle Interaction

The remote control of biocatalytic processes in an extracellular medium is an exciting idea to deliver innovative solutions in the biocatalysis field. With this purpose, metallic nanoparticles (NPs) are great candidates, as their inherent thermal, electric, magnetic, and plasmonic properties can readily be manipulated upon external stimuli. Exploring the unique NP properties beyond an anchoring platform for enzymes brings up the opportunity to extend the efficiency of biocatalysts and modulate their activity through triggered events. In this review, we discuss a set of external stimuli, such as light, electricity, magnetism, and temperature, as tools for the regulation of nanobiocatalysis, including the challenges and perspectives regarding their use. In addition, we elaborate on the use of combined stimuli that create a more refined framework in terms of a multiresponsive system. Finally, we envision this review might instigate researchers in this field of study with a set of promising opportunities in the near future.

Rational reformation of Corynebacterium glutamicum for producing L-lysine by one-step fermentation from raw corn starch

This article focuses on engineering Corynebacterium glutamicum to produce L-lysine efficiently from starch using combined method of "classical breeding" and "genome breeding." Firstly, a thermo-tolerable L-lysine-producing C. glutamicum strain KT_45-6 was obtained after multi-round of acclimatization at high temperature. Then, amylolytic enzymes were introduced into strain KT_45-6, and the resultant strains could use starch for cell growth and L-lysine production except the strain with expression of isoamylase. In addition, co-expression of amylolytic enzymes showed a good performance in starch degradation, cell growth and L-lysine production, especially co-expression of α-amylase (AA) and glucoamylase (GA). Moreover, L-lysine yield was increased by introducing AA-GA fusion protein (i.e., strain KT_45-6S-5), and finally reached to 23.9 ± 2.3 g/L in CgXII^IPM-medium. It is the first report of an engineered L-lysine-producing strain with maximum starch utilization that may be used as workhorse for producing amino acid using starch as the main feedstock. KEY POINTS: • Thermo-tolerable C. glutamicum was obtained by temperature-induced adaptive evolution. • The fusion order between AA and GA affects the utilization efficiency of starch. • C. glutamicum with starch utilization was constructed by optimizing amylases expression.

Expression, biochemical and structural characterization of high-specific-activity β-amylase from Bacillus aryabhattai GEL-09 for application in starch hydrolysis

BACKGROUND

β-amylase (EC 3.2.1.2) is an exo-enzyme that shows high specificity for cleaving the α-1,4-glucosidic linkage of starch from the non-reducing end, thereby liberating maltose. In this study, we heterologously expressed and characterized a novel β-amylase from Bacillus aryabhattai.

RESULTS

The amino acid-sequence alignment showed that the enzyme shared the highest sequence identity with β-amylase from Bacillus flexus (80.73%) followed by Bacillus cereus (71.38%). Structural comparison revealed the existence of an additional starch-binding domain (SBD) at the C-terminus of B. aryabhattai β-amylase, which is notably different from plant β-amylases. The recombinant enzyme purified 4.7-fold to homogeneity, with a molecular weight of ~ 57.6 kDa and maximal activity at pH 6.5 and 50 °C. Notably, the enzyme exhibited the highest specific activity (3798.9 U/mg) among reported mesothermal microbial β-amylases and the highest specificity for soluble starch, followed by corn starch. Kinetic analysis showed that the K_m and k_cat values were 9.9 mg/mL and 116961.1 s^- 1, respectively. The optimal reaction conditions to produce maltose from starch resulted in a maximal yield of 87.0%. Moreover, molecular docking suggested that B. aryabhattai β-amylase could efficiently recognize and hydrolyze maltotetraose substrate.

CONCLUSIONS

These results suggested that B. aryabhattai β-amylase could be a potential candidate for use in the industrial production of maltose from starch.

Engineered tyrosinases with broadened bio-catalysis scope: immobilization using nanocarriers and applications

Enzyme immobilization is a widely used technology for creating more stable, active, and reusable biocatalysts. The immobilization process also improves the enzyme's operating efficiency in industrial applications. Various support matrices have been designed and developed to enhance the biocatalytic efficiency of immobilized enzymes. Given their unique physicochemical attributes, including substantial surface area, rigidity, semi-conductivity, high enzyme loading, hyper catalytic activity, and size-assisted optical properties, nanomaterials have emerged as fascinating matrices for enzyme immobilization. Tyrosinase is a copper-containing monooxygenase that catalyzes the o-hydroxylation of monophenols to catechols and o-quinones. This enzyme possesses a wide range of uses in the medical, biotechnological, and food sectors. This article summarizes an array of nanostructured materials as carrier matrices for tyrosinase immobilization. Following a detailed background overview, various nanomaterials, as immobilization support matrices, including carbon nanotubes (CNTs), carbon dots (CDs), carbon black (CB), nanofibers, Graphene nanocomposite, platinum nanoparticles, nano-sized magnetic particles, lignin nanoparticles, layered double hydroxide (LDH) nanomaterials, gold nanoparticles (AuNPs), and zinc oxide nanoparticles have been discussed. Next, applied perspectives have been spotlights with particular reference to environmental pollutant sensing, phenolic compounds detection, pharmaceutical, and food industry (e.g., cereal processing, dairy processing, and meat processing), along with other miscellaneous applications.

Highly Selective Entrapment of His-Tagged Enzymes on Superparamagnetic Zirconium-Based MOFs with Robust Renewability to Enhance pH and Thermal Stability

Metal-organic frameworks (MOFs), as a kind of poriferous nanoparticle, are promising candidates for enzyme immobilization to enhance their stability and reusability. However, most MOFs could not specifically immobilize enzymes and regenerate easily, which inevitably leads to serious high consumption and environmental pollution. In this study, renewable and magnetic MOFs were first constructed to specially immobilize His-tagged enzymes from the cell lysates without purification. The immobilized β-glucuronidase exhibited wider pH adaptability and temperature stability. The relative activity of immobilized β-glucuronidase was still maintained at ∼80% after eight cycles. Importantly, after simple treatment, the immobilization capacity of regenerated MOFs after simple treatment was restored to more than 90% in the first three times. The specific magnetic MOFs were proven to be an efficient and renewable platform for one-step immobilization and purification of His-tagged enzymes, showing great potential in industrial applications of nanotechnology and biocatalysis.

Highly enhanced activity and stability via affinity induced immobilization β-glucosidase from Aspergillus niger onto amino-based silica for the biotransformation of ginsenoside Rb1

In this study, an enzyme immobilization method for the effective biotransformation of ginsenoside Rb1 to impart activity and stability was developed. Using a hydrolase enzyme model, β-glucosidase from Aspergillus niger, immobilization within chemically affinity-linked amino-based silica provided an immobilization efficiency 5.86-fold higher than that of free enzyme. Compared with the free enzyme, the immobilized enzyme functioned optimally at a wider pH range and had higher thermostability. The optimum pH for the free and immobilized enzymes was 5.5. The optimal reaction temperature of the immobilized enzyme was 45 °C, which was 5 °C higher than that of the free enzyme. The Michaelis constant (K_m) values before and after immobilization were 0.482 mmol•L^-1 and 0.387 mmol•L^-1, respectively. The catalytic rate (K_cat) for the immobilized and free enzymes was 22.269 mmol•L^-1and 8.800 mmol•L^-1, respectively, and the catalytic efficiency (K_cat/K_m) activity of the immobilized enzyme was 3.30-fold higher than that of the free enzyme. The immobilized enzyme could preserve 97 % of the activity after 45 cycles of repeated use. The high catalytic activity and significant operational stability are beneficial for industrial applications.

Robust nanocarriers to engineer nanobiocatalysts for bioprocessing applications

The synergistic integration of bio-catalysis engineering with nanostructured materials, as unique multifunctional carrier matrices, has emerged as a new interface of nanobiocatalysis (NBC). NBC is an emerging innovation that offers significant considerations to expand the designing and fabrication of robust catalysts at the nanoscale with improved catalytic characteristics for multipurpose bioprocessing applications. In addition, nanostructured materials with unique structural, physical, chemical, and functional entities have manifested significant contributions in mimicking the enzyme microenvironment. A fine-tuned enzyme microenvironment with an added-value of NBC offers chemo- regio- and stereo- selectivities and specificities. Furthermore, NBC is growing rapidly and will become a powerful norm in bio-catalysis with much controlled features, such as selectivity, specificity, stability, resistivity, induce activity, reaction efficacy, multi-usability, improved mass transfer efficiency, high catalytic turnover, optimal yield, ease in recovery, and cost-effectiveness. Considering the above critics and unique structural, physicochemical, and functional attributes, herein, we present and discuss advances in NBC and its bioprocessing applications in different fields. Briefly, this review is focused on four parts, i.e., (1) NBC as a drive towards applied nanobiocatalysts (as an introduction with opportunities), (2) promising nanocarriers to develop nanobiocatalysts, (3) applications in the fields of biotransformation, biofuel production, carbohydrate hydrolysis, bio-/nanosensing, detergent formulations, and extraction and purification of value-added compounds, and (4) current challenges, concluding remarks, and future trends.

Ultrasonic coupling with electrical current to effective activation of Persulfate for 2, 4 Dichlorophenoxyacetic acid herbicide degradation: modeling, synergistic effect, and a by-product study

In this research work, we investigated the ability of the oxidative degradation of 2, 4-Dichlorophenoxy acetic acid herbicide via ultrasonic-assisted in electro-activation of the persulfate system in the presence of nano-zero valent iron. The effect of experimental parameters such as pH value [4-8], electrical current (0.5-1 A), persulfate concentration (0.25-0.5 mg.l-1), nano zero-valent iron dose (0.05-0.1 mg.l-1), and initial organic pollutant concentration (50-100 mg.l-1) on the ultrasonic-electropersulfate process performance was assessed via central composite design. The combination of ultrasonic waves with the electrochemical process to activation of persulfate showed better efficiency into 2, 4-Dichlorophenoxy acetic acid herbicide degradation compared to their implementation in individual and binary systems. Following optimal conditions (pH = 5.62, 0.80 A applied electrical current, 0.39 mg/L persulfate concentration, 0.07 mg/L nano-zero valent iron, and 50 mg/L 2,4-Dichlorophenoxy acetic acid concentration in 40 min reaction), nearly 91% removal was done. Moreover, the complete removal of 2, 4-Dichlorophenoxy acetic acid, 92% COD, and 88% TOC removal was achieved by this process near 140 min reaction. The scavenging experiment confirmed the role of free oxidizing species in the degradation of 2, 4-Dichlorophenoxy acetic acid during the process. Approximately 50% improved 2, 4-Dichlorophenoxy acetic acid removal in the process against the inclusive efficiency of single mechanisms. The obtained results were fitted to the pseudo-first-order kinetic model with a high correlation coefficient (R2 = 0.96). Five important intermediate products of 2, 4-D oxidation were 2, 4-dichlorophenol (2, 4-DCP), 2, 6-dichlorophenol (2, 6-DCP), 4, 6 dichlororesorcinol (4, 6-DCR), 2-chlorohydroquinone (2-CHQ), and 2-chloro-1, 4-benzoquinone (2-CBQ). In the end, can be employed as a satisfactory advanced oxidation process in high mineralization of 2, 4-D and refractory organic pollutants.

Production of L-alanyl-L-glutamine by immobilized Escherichia coli expressing amino acid ester acyltransferase

Production of Ala-Gln by the E. coli expressing α-amino acid ester acyltransferase was a promising technical route due to its high enzyme activity, but the continuous production ability still needs to improve. Therefore, the immobilized E. coli expressing α-amino acid ester acyltransferase was applied for the continuous production of Ala-Gln. Four materials were selected as embedding medium for the whole cell entrapment of recombinant bacteria. Calcium alginate beads were found to be the most proper entrapment carrier for production of Ala-Gln. The temperature, pH, and repeatability of the immobilized cell were compared with free cells. Results showed that immobilization cell could maintain a wider range of temperature/pH and better stability than free cell (20-35 °C/pH 8.0-9.0, and 25 °C/pH 8.5, respectively). On this basis, continuous production strategy was put forward by filling the immobilized cell in the tubular reactor with multiple control conditions. The Ala-Gln by immobilization cell achieved the productivity of 2.79 mg/(min*mL-CV) without intermittent time. Consequently, these findings suggest that the immobilization technique has potential applications in the production of Ala-Gln by biotechnological method. KEY POINTS: • Immobilization helps to achieve high efficiency production of Ala-Gln. • Immobilized cells have better stability than free cells. • Sodium alginate is the most suitable immobilized material.

Facile one-step targeted immobilization of an enzyme based on silane emulsion self-assembled molecularly imprinted polymers for visual sensors

Immobilized enzymes play significant roles in many practical applications. However, the enzymes need to be purified before immobilization by conventional immobilizing methods, and the purification process is expensive, laborious, complicated and results in a decrease of the enzymatic activity. So, we present a novel method by a facile one-step targeted immobilization of an enzyme without a purification process from complex samples. For this purpose, a novel molecularly imprinted polymer was prepared via a silane emulsion self-assembly method using boric acid-modified Fe3O4 nanoparticles as magnetic nuclei, horseradish peroxidase as a template, 3-aminopropyltriethoxysilane as a functional monomer and tetraethyl orthosilicate as a crosslinking agent. The molecularly imprinted polymers were characterized using a scanning electron microscope, X-ray photoelectron spectroscope, vibrating sample magnetometer and X-ray diffractometer. The as-prepared and characterized materials were employed to immobilize horseradish peroxidase from a crude extract of horseradish. Moreover, the immobilized horseradish peroxidase was employed to develop visual sensors for the detection of glucose and sarcosine. This study demonstrated that the molecularly imprinted polymers prepared via the silane emulsion self-assembly method can facilely immobilize horseradish peroxidase from a crude extract of horseradish without any purification process. The developed visual method based on the immobilized horseradish peroxidase shows great potential applications for the visual detection of glucose and sarcosine.

Nanoparticles decorated carbon nanotubes as novel matrix: A comparative study of influences of immobilization on the catalytic properties of Lensculinarisβ-galactosidase (Lcβ-gal)

In the present study, Multiwalled carbon nanotubes (MWCNT) decorated with two different nanoparticles namely tungsten disulfide (WS₂) and tin oxide (SnO₂), nanocomposites (NCs) were synthesized via hydrothermal method. Spectroscopic studies showed that both synthesized NCs possess nearly same functional groups but MWCNT-SnO₂ NCs are rich in O-functional group. Microscopic studies revealed that both NCs have different morphological microstructure. Lens culinaris β-galactosidase (Lcβ-gal) was immobilized using glutaraldehyde cross-linker resulted in immobilization efficiency of 91.5% and 88% with MWCNT-WS₂ and MWCNT-SnO₂ NCs, respectively. Remarkable increase in rate of hydrolysis of whey lactose has been observed with both NCs i.e. Lcβ-gal immobilized MWCNT-WS₂ hydrolyzes the 97% whey lactose in 1.5 h while MWCNT-SnO₂ showed maximum 92% of whey hydrolysis in 2 h at optimum conditions. Both nanobiocatalyst could serve as a promising candidates for dairy industries and would offer a potential platform for enzyme based biosensor fabrication.

Immobilization of fenugreek β-amylase onto functionalized tungsten disulfide nanoparticles using response surface methodology: Its characterization and interaction with maltose and sucrose

In this communication, fenugreek β-amylase was immobilized onto functionalized tungsten disulfide nanoparticles through cross-linker glutaraldehyde and successful immobilization was confirmed by SEM, AFM and FTIR spectroscopy. To make the process economical and efficient, optimization of independent variables was carried out using Box-Behnken design of response surface methodology. Approximately similar predicted (85.6%) and experimental (84.2%) immobilization efficiency revealed that the model is suitable for design of space. Optimum temperature was calculated to be 60 °C. After immobilization, an increased K_m (2.12 times) and a decreased V_max (0.58 times), indicated inaccessibility of active site residues to the substrate. The immobilized enzyme retained 77% relative activity after 10 uses whereas 40% residual activity was obtained after 120 days. An increased half-life with concomitantly decreased kinetic rate constant revealed that the immobilized enzyme is more stable at a higher temperature and the process followed first-order kinetics (R² > 0.93). The limit of detection for maltose and sucrose fluorescence biosensor was found to be 0.052 and 0.096 mM, respectively. Thermodynamic parameters such as changes in Gibbs free energy (ΔG < 0), enthalpy (ΔH > 0) and entropy (ΔS >0) revealed that the process is spontaneous and endothermic, driven by hydrophobic interactions. Thermo-stability data at higher temperature for the immobilized enzyme makes it a suitable candidate for industrial applications in the production of maltose in food and pharmaceutical industries. Furthermore, fluorescence biosensor could be used to detect and quantify maltose and sucrose to maintain the quality of industrial products.

Recent development in the application of immobilized oxidative enzymes for bioremediation of hazardous micropollutants - A review

During the past several years, abundant progresses has been made in the development of immobilized oxidative enzymes with focus on finding new support materials, improving the immobilization methods and their applications. Nowadays, immobilized oxidative enzymes are broadly accepted as a green way to face the challenge of high amounts of micropollutants in nature. Among all oxidative enzymes, laccases and horseradish peroxidase were used frequently in recent years as they are general oxidative enzymes with ability to oxidize various types of compounds. Immobilized laccase or horseradish peroxidase are showed better stability, and reusability as well as easy separation from reaction mixture that make them more favorable and economic in compared to free enzymes. However, additional improvements are still essential such as: development of the new materials for immobilization with higher capacity, easy preparation, and cheaper price. Moreover, immobilization methods are still need improving to become more efficient and avoid enzyme wasting during immobilization and enzyme leakage through working cycles.

Fabrication of the robust and recyclable tyrosinase-harboring biocatalyst using ethylenediamine functionalized superparamagnetic nanoparticles: nanocarrier characterization and immobilized enzyme properties

Immobilized tyrosinase onto the functionalized nanoparticles with the ability to be reused easily in different reaction cycles to degrade phenolic compounds is known as a substantial challenge, which can be overcome through surface modification of the particles via proper chemical groups. Herein, the synthesis and silica coating of superparamagnetic nanoparticles using a simple procedure as well as their potential for tyrosinase immobilization were demonstrated. Therefore, N-[3-(trimethoxysilyl)propyl]ethylenediamine was used to functionalize the silica-coated nanoparticles with amine groups. Then, the ethylenediamine functionalized magnetic nanoparticles (EMNPs) were suspended in a solution containing tetrahydrofuran and cyanuric chloride (as an activating agent) to modify nanocarriers. To immobilize enzyme, a mixture of tyrosinase and cyanuric chloride functionalized magnetic nanoparticle (Cyc/EMNPs) was shaken at room temperature. The particles were characterized by EDX, TGA, SEM, FTIR, and TEM. As a result, the successful functionalization of the magnetic nanoparticles and covalent attachment of tyrosinase onto the Cyc/EMNPs were confirmed. The fabricated nano-biocatalyst particles were semi-spherical in shape. The immobilized tyrosinase (Ty-Cyc/EMNPs) exhibited remarkable reusability of six consecutive reaction cycles while no considerable loss of activity was observed for the first three cycles. Moreover, the excellent stability of the biocatalyst at different temperatures and pHs was proved. The Ty-Cyc/EMNPs with interesting features are promising for practical applications in biosensor development and wastewater treatment.

Immobilization of horseradish peroxidase on electrospun magnetic nanofibers for phenol removal

In this study, Fe₃O₄/polyacrylonitrile (PAN) magnetic nanofibers (MNFs) were fabricated by electrospinning method to immobilize the horseradish peroxidase (HRP), making which a complex platform for phenol removal application. Results indicated that, the average diameter of MNFs was about 200-400 nm and the maximum saturation magnetic induction was 19.03 emu/g. Compared with the free HRP, the modified HRP showed no change in optimum pH, but showed higher catalytic activity. Moreover, HRP immobilized MNFs (H-MNFs) with 40% Fe₃O₄ nanoparticles loading had the lowest HRP loading, but had the highest relative activity, because of the magnetic synergy with the presence of MNPs. Subsequently, the 40% H-MNFs was used for the remediation of phenol wastewater, achieved the removal efficiency of phenol to 85% in the first round use, and remained 52% of efficiency after 5 recycles using. It was expected that the H-MNFs could be a potential application in wastewater treatment such as phenol removal.

Production of recombinant beta-amylase of Bacillus aryabhattai

In this study, the effects of carbon source, nitrogen source, and metal ions on cell growth and Bacillus aryabhattai β-amylase production in recombinant Brevibacillus choshinensis were investigated. The optimal medium for β-amylase production, containing glucose (7.5 g·L^-1), pig bone peptone (40.0 g·L^-1), Mg²⁺ (0.05 mol·L^-1), and trace metal elements, was determined through single-factor experiments in shake flasks. When cultured in the optimized medium, the β-amylase yield reached 925.4 U mL^-1, which was 7.2-fold higher than that obtained in the initial medium. Besides, a modified feeding strategy was proposed and applied in a 3-L fermentor fed with glucose, which achieved a dry cell weight of 15.4 g L^-1. Through this cultivation approached 30 °C with 0 g·L^-1 initial glucose concentration, the maximum β-amylase activity reached 5371.8 U mL^-1, which was 41.7-fold higher than that obtained with the initial medium in shake flask.

Applications of RAFT polymerization for chemical and enzymatic stabilization of l-asparaginase conjugates with well-defined poly(HPMA)

HPMA RAFT polymerization and activation with variable linker chemistry for stabilization of l-asparaginase against pH, temperature, freeze–thaw and proteolytic stresses.

Co-immobilization of cellulase and lysozyme on amino-functionalized magnetic nanoparticles: An activity-tunable biocatalyst for extraction of lipids from microalgae

An activity-tunable biocatalyst for Nannochloropsis sp. cell-walls degradation was prepared by co-immobilization of cellulase and lysozyme on the surface of amino-functionalized magnetic nanoparticles (MNPs) employing glutaraldehyde. The competition between cellulase and lysozyme during immobilization was caused by the limited active sites of the MNPs. The maximum recovery of activities (cellulase: 78.9% and lysozyme: 69.6%) were achieved due to synergistic effects during dual-enzyme co-immobilization. The thermal stability in terms of half-life of the co-immobilized enzymes was three times higher than that in free form and had higher catalytic efficiency for hydrolysis of cell walls. Moreover, the co-immobilized enzymes showed greater thermal stability and wider pH tolerance than free enzymes under harsh conditions. Furthermore, the co-immobilized enzymes retained up to 60% of the residual activity after being recycled 6 times. This study provides a feasible approach for the industrialization of enzyme during cell-walls disruption and lipids extraction from Nannochloropsis sp.

Chemical and Biochemical Approach to Make a Perfect Biocatalytic System on Carbonaceous Matrices

Enzymatic processes are widely used in food industry, pharmacy, cosmetic and household chemistry, and medicine. However, the common and efficient application of the biological catalysts is limited by a number of factors that influence enzymes activity. One of the most frequent methods to improve the biocatalysts' properties is immobilization. This chapter presents a recent overview of our attempts to obtain the perfect biocatalytic system. The experimental approach, proposed in this chapter, includes the critical points like: the choice of adequate immobilization method, most suitable carrier, determination of enzyme kinetic parameters, stability, and toxicity of obtained systems. As carbon materials including graphene-derived materials offer unique properties and a plenty of different modifications, these parameters seem to be of decisive importance to understand chemistry of complex systems. Consideration of all the mentioned requirements lead us to the conclusion that graphene oxide could be the best candidate for support in perfect biocatalytic systems.

Enhanced activity and stability of papain by covalent immobilization on porous magnetic nanoparticles

Papain enzyme was successfully immobilized by covalent bonding onto biocompatible Fe₃O₄/SF nanoparticles, which were prepared with the soft template of silk fibroin (SF). The optimized immobilization condition is pH6.0, hydrolysis time of 60min, and an enzyme/support ratio of 10.0mg/g. Compared with free papain, the immobilized papain exhibits a high effective activity, broader working pH and temperature. This immobilized papain can be separated from the solution by the external magnetic field for cyclic utilization, and 70% of initial activity was retained after eight consecutive operations while completely loss of proteolytic activity for the free papain. Furthermore, the immobilized papain maintained 85% of their initial activity after being stored for 28days. Kinetic parameters, maximum reaction rate (V_max) and Michaelis constant (K_m) of immobilized papain, were determined as 4.95mg/l·min and 0.23mg/ml, larger than its free counterpart. All the results above indicated that the immobilized papain onto magnetic Fe₃O₄/SF nanoparticles would have potential industrial and medical applications.

An antioxidant rich novel β-amylase from peanuts (Arachis hypogaea): Its purification, biochemical characterization and potential applications

β-Amylase from un-germinated seeds of peanut (Arachis hypogaea) was purified to apparent electrophoretic homogeneity with final purification fold of 205 and specific activity of 361μmol/min/mg protein. The enzyme was purified employing simple purification techniques for biochemical characterization. The purified enzyme was identified as β-amylase with M_r of 31kDa. The enzyme displayed its optimum catalytic activity at pH5.0 and 60°C with activation energy of 4.5kcal/mol and Q₁₀ 1.2. The enzyme displayed K_m and V_max values, for soluble potato starch of 1.28mg/mL and 363.63μmol/min/mg, respectively. Thermal inactivation of β-amylase at 65°C resulted into first-order kinetics with rate constant 0.0126min^-1 and t_½ 55min. The enzyme was observed to act on native granular potato starch, which could minimize the high cost occurring from solubilization of starch in industries. Enzyme fractions scavenge 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical, indicating its antioxidative nature. In addition, the purified β-amylase was successfully utilized for the improvement of antioxidant potential of wheat. These findings suggest that β-amylase from peanuts have potential application in food and pharmaceutical industries.