Ultrasonic hyperactivation of cellulase immobilized on magnetic nanoparticles

Studies on the preparation of a sufficient carrier from egg protein and carrageenan for cellulase with optimization and application

Egg protein (EP) concentration, pH, and glutaraldehyde (GA) concentration were optimized using Box Behnken design (BBD) to prepare GA-EP-Carr (Carrageenan) beads as a carrier for Aspergillus niger MK981235 cellulase. It was recommended that the concentrations of GA, and EP be set at 11.21% (w/v), 8% (w/w), and pH 3, respectively. It was determined that 60 °C and 2% for free form and 60 °C and 3% for im-cellulase were the optimum temperature and CMC concentration parameters for maximum enzyme activity. Free and im-cellulase were determined to have Km and Vmax of 2.22 mg.ml-1 and 1.76 µmol.ml-1.min-1, and 4.55 mg.ml-1 and 3.33 µmol.ml-1.min-1, respectively. Covalent coupling of A. niger cellulase to GA- EP- Carr beads improved its thermodynamic parameters T1/2 and D-values by 2.48, 2.01, and 2.36 times at 40, 50, and 60 °C, respectively. GA- EP- Carr im-cellulase was 100% active for 60 days at 4 °C and can be used for CMC hydrolysis for 20 successive cycles. GA- EP- Carr im-cellulase showed remarkable efficiency in the clarification of mango, peach, grape, and orange juices emphasized by TSS (total soluble solids), turbidity, and reducing sugar measurements for 3 successive cycles. GA- EP- Carr im-cellulase can be applied with high efficiency in juice industry.

Enzymatic preparation of diacylglycerols: lipase screening, immobilization, characterization and glycerolysis performance

BACKGROUNDS

Glycerolysis, with its advantages of readily available raw materials, simple operation, and mild reaction conditions, is a primary method for producing diacylglycerol (DAG). However, enzymatic glycerolysis faces challenges such as high enzyme costs, low reuse efficiency, and poor stability. The study aims to develop a cost-effective immobilized enzyme by covalently binding lipase to pre-activated carriers through the selection of suitable lipases, carriers, and activating agents. The optimization is intended to improve the glycerolysis reaction for efficient DAG production.

RESULTS

Lipase CN-TL (from Thermomyces lanuginosus) was selected through glycerolysis reaction and molecular docking to catalyze the glycerolysis reaction. Optimizing the immobilization method by covalently binding CN-TL to poly(ethylene glycol) diglycidyl ether (PEGDGE)-preactivated resin LX-201A resulted in the preparation of the immobilized enzyme TL-PEGDGE-LX. The immobilized enzyme retained over 90% of its initial activity after five consecutive reactions, demonstrating excellent reusability. The DAG content in the product remained at 84.8% of its initial level, further highlighting the enzyme's potential for reusability and its promising applications in the food and oil industries.

CONCLUSIONS

The immobilized lipase TL-PEGDGE-LX, created by covalently immobilizing lipase CN-TL on PEGDGE-preactivated carriers, demonstrated broad applicability and excellent reusability. This approach offers an economical and convenient immobilization strategy for the enzymatic glycerolysis production of DAG. © 2024 Society of Chemical Industry.

Epoxy-Affixed ZIF-8/CS/Cellulase: a Sustainable Approach for Hydrolysis of Agricultural Waste to Reducing Sugars

Cellulase was effectively immobilized onto an epoxy-bound chitosan-modified zinc metal-organic framework (epoxy/ZIF-8/CS/cellulase) support, yielding a conjugation rate of 0.64 ± 0.02 mg/cm2 and retaining 80.01 ± 0.01% of its specific activity. The bare and cellulase-bound supports was characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, atomic force microscopy and energy-dispersive X-ray spectroscopy. The immobilized enzyme exhibited optimal activity at pH 5.5 and a temperature of 70 ℃. The efficiency, stability and reactivity of the enzyme improved after immobilization, as evidenced by a decrease in activation energy, enthalpy and Gibbs free energy along with an increase in entropy change. The epoxy-affixed ZIF-8/CS/cellulase strip was successfully employed for rice husk hydrolysis achieving an impressive conversion efficiency of 95%. The method demonstrated a linear range from 0.1 to 0.9% (0.1 × 10-2 to 0.9 × 10-2 mg/ml) and exhibited a strong correlation (R2 = 0.998) with the widely adopted 3, 5-dinitrosalicylic acid method. The epoxy/ZIF-8/CS bound cellulase exhibited remarkable thermal stability, retaining 100% of its activity at 70 °C, in contrast to just 53% for the free enzyme and displayed a half-life of 21 days after storage at 4 °C compared to 9 days for the free enzyme. Furthermore, it retained over 95% activity after 12 h at pH levels of 4.5 and 5.5 and showcased excellent reusability, maintaining activity over 25 cycles. Overall, this method offers high conversion efficiency and selectivity under benign conditions, with no undesirable by-products, making it a cost-effective solution for the routine hydrolysis of lignocellulosic biomass feedstock.

Pancreatic lipase immobilization on cellulose filter paper for inhibitors screening and network pharmacology study of anti-obesity mechanism

The discovery of pancreatic lipase (PL) inhibitors is an essential route to develop new anti-obesity drugs. In this experiment, chitosan was used to add amino groups to cellulose filter paper (CFP) and then glutaraldehyde was used to covalently combine PL with amino-modified CFP through the Schiff base reaction. Under optimal immobilization conditions, CFP immobilized PL has a wide range of pH and temperature tolerance, as well as excellent reproducibility, reusability and storage stability. Subsequently, 26 natural products (NPs) were screened by immobilized PL with black tea extract having the highest inhibition rate. Three compounds with binding effects on PL (epigallocatechin gallate, theaflavin-3-gallate and theaflavin-3,3'-digallate) were captured. Molecular docking proved that these three compounds have a strong binding affinity for PL. Fluorescence spectra further revealed that theaflavin-3,3'-digallate could statically quench the intrinsic fluorescence of pancreatic lipase. The molecular docking and thermodynamic parameters indicated that electrostatic interaction was considered as the main interaction force between PL and theaflavin-3,3'-digallate. Finally, the potential anti-obesity targets and pathways of the three compounds were discussed through network pharmacology. This study not only proposes a simple and efficient method for screening PL inhibitors, but also sheds light on the anti-obesity mechanism of active compounds in black tea.

Cellulase immobilization on nano-chitosan/chromium metal-organic framework hybrid matrix for efficient conversion of lignocellulosic biomass to glucose

In the current work, cellulase from Aspergillus niger was successfully immobilized on a novel epoxy-affixed chromium metal-organic framework/chitosan (Cr@-MIL-101/CS) support via covalent method using glutaraldehyde as a crosslinker. The bare and cellulase-bound support was characterized by using various microscopic and spectroscopic techniques. Immobilized cellulase exhibited a high immobilization yield of 0.7 ± 0.01 mg/cm2, retaining 87.5 ± 0.04% of its specific activity and displaying enhanced catalytic performance. The immobilized enzyme was maximally active at pH 5.0, temperature 65 °C and 0.9 × 10-2 mg/ml saturating substrate concentration and the half-lives of free and immobilized cellulases were approximately 9 and 19 days, respectively. The decrease in activation energy, enthalpy change, and Gibbs free energy change, coupled with an increase in entropy change upon immobilization, indicated that the enzyme's efficiency, stability, and spontaneity in catalyzing the reaction were enhanced by immobilization. Additionally, the immobilized cellulase efficiently converted rice husk cellulose to glucose, with a quantification limit of 0.05%, linear measurement ranging from 0.1 to 0.9%, and 8.5% conversion efficiency. The present method exhibited a strong correlation (R2 = 0.998) with the DNS method, validating its reliability. Notably, the epoxy/Cr@-MIL-101/CS-bound cellulase demonstrated impressive thermal and pH stabilities, retaining 50% of its activity at 75 °C and over 96% at pH levels of 4.5 and 5.0 after 12 h. Furthermore, it showed excellent reusability, preserving 80% of its activity after 15 cycles and maintaining 50% of its activity even after 20 days of storage. These results suggest that epoxy/Cr@-MIL-101/CS/cellulase composites could be very effective for large-scale cellulose hydrolysis applications.

Convenient preparation of indigo from the Ieaves of Baphicacanthus cusia(Nees) Bremek by enzymatic method and its MALDI-TOF-MS and UPLC-Q-TOF/MS analysis

The manufacturing of indigo naturalis requires prolonged leaf soaking and lime stirring; the resulting indigo purity is less than 3.00% and the yield of indigo (measured in stems and leaves weight) is less than 0.50%, making it unsuitable for use in industrial procedures like printing and dyeing. An enzymatic method of creating indigo without the requirement for lime was investigated in order to generate high purity indigo. Single factor tests were performed to optimize the enzymatic preparation conditions. The findings showed that 60 °C, pH 5.5, 200 mL of leaves extract containing 0.45 mg/mL indican, and a 4:1 ratio of the acidic cellulose (activity: 9000 U/mL, liquid) to indican were the ideal parameters for enzymatic preparation. The yield of indigo was 40.32%, and the contents of indigo and indirubin were 37.37% and 2.30%, respectively. MALDI-TOF-MS in positive ion mode and UPLC-Q-TOF-MS in both positive and negative ion modes were used to analyze indigo extracts from Baphicacanthus cusia(Nees) Bremek by enzymatic preparation. It has been discovered that 13 alkaloids, 5 organic acids, 3 terpenoids, 3 steroids, 2 flavones, and 7 other compounds are present in indigo extracts. The presence of the indigo, indirubin, isorhamnetin, tryptanthrin, indigodole B, and indigodole C determined by UPLC-Q-TOF-MS was verified by MALDI-TOF-MS analysis. The enzymatic preparation of indigo extracts kept the same chemical makeup as conventional indigo naturalis. Thermal analysis and SEM morphology were used to confirm that there was no lime in the indigo extract. During the enzymatic process, Baphicacanthus cusia (Nees) Bremek was employed more effectively, increasing the yield and purity of indigo.

Sono-activation of food enzymes: From principles to practice

Over the last decade, sono-activation of enzymes as an emerging research area has received considerable attention from food researchers. This kind of relatively new application of ultrasound has demonstrated promising potential in facilitating the modern food industry by broadening the application of various food enzymes, improving relevant industrial unit operation and productivity, as well as increasing the yield of target products. This review aims to provide insight into the fundamental principles and possible industrialization strategies of the sono-activation of food enzymes to facilitate its commercialization. This review first provides an overview of ultrasound application in the activation of food protease, carbohydrase, and lipase. Then, the recent development on ultrasound activation of food enzymes is discussed on aspects including mechanisms, influencing factors, modification effects, and its applications in real food systems for free and immobilized enzymes. Despite the far fewer studies on sono-activation of immobilized enzymes compared with those on free enzymes, we endeavored to summarize the relevant aspects in three stages: ultrasound pretreatment of free enzyme/carrier, assistance in immobilization process, and modification of the already immobilized enzyme. Lastly, challenges for the scalability of ultrasound in these target areas are discussed and future research prospects are proposed.

β-Glucosidase Immobilized on Magnetic Nanoparticles: Controlling Biomolecule Footprint and Particle Functional Group Density to Navigate the Activity-Stability Tradeoff

In the present work, the immobilized footprint of β-glucosidase (BGL) on silica-coated iron oxide was explored to produce reusable catalysts with flexible active sites for high activity and heightened storage stability. Synthesized iron oxide particles were coated with silica and functionalized with various densities of (3-aminopropyl)triethoxysilane (APTES) to obtain particles with amine densities ranging from 0 to 3 × 10^-5 mol/g particle. The amine-modified particles were activated with glutaraldehyde, and subsequently, BGL was immobilized using either a 0.1 or 1 mg/mL enzyme solution to produce biomolecules with a large or small footprint on the particle surface. The initial activity, activity for subsequent hydrolysis cycles, activity after extended storage, and biomolecule footprint were studied as a function of APTES density and concentration of enzyme used for immobilization. At high immobilization amounts, the specific activity and footprint were reduced, but the immobilized biomolecules were stable during storage. However, at low enzyme immobilizations, the activity of the enzymes was retained, the immobilized enzymes adopted large footprints, and the storage stability increased with APTES density relative to the free enzyme. These results highlight how controlling both the protein load and functional group density can yield immobilized enzymes possessing high activity, which are stable during storage.

The Existing Recovery Approaches of the Huangjiu Lees and the Future Prospects: A Mini Review

Huangjiu lees (HL) is a byproduct in Chinese Huangjiu production with various nutrient and biological functional components. Without efficient treatment, it could cause environmental issues and bioresource wasting. Existing dominant recovery approaches focus on large-scale disposal, but they ignore the application of high-value components. This study discusses the advantages and limitations of existing resourcing approaches, such as feed, food and biogas biological production, considering the efficiency and value of HL resourcing. The extraction of functional components as a suggestion for HL cascade utilization is pointed out. This study is expected to promote the application of HL resourcing.

Enhancement of the Catalytic Performance and Operational Stability of Sol-Gel-Entrapped Cellulase by Tailoring the Matrix Structure and Properties

Commercial cellulase Cellic CTec2 was immobilized by the entrapment technique in sol–gel matrices, and sol–gel entrapment with deposition onto magnetic nanoparticles, using binary or ternary systems of silane precursors with alkyl- or aryl-trimethoxysilanes, at different molar ratios. Appropriate tailoring of the sol–gel matrix allowed for the enhancement of the catalytic efficiency of the cellulase biocatalyst, which was then evaluated in the hydrolysis reaction of Avicel microcrystalline cellulose. A correlation between the catalytic activity with the properties of the sol–gel matrix of the nanobiocatalysts was observed using several characterization methods: scanning electron microscopy (SEM), fluorescence microscopy (FM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA/DTA). The homogeneous distribution of the enzymes in the sol–gel matrix and the mass loss profile as a function of temperature were highlighted. The influence of temperature and pH of the reaction medium on the catalytic performance of the nanobiocatalysts as well as the operational stability under optimized reaction conditions were also investigated; the immobilized biocatalysts proved their superiority in comparison to the native cellulase. The magnetic cellulase biocatalyst with the highest efficiency was reused in seven successive batch hydrolysis cycles of microcrystalline cellulose with remanent activity values that were over 40%, thus we obtained promising results for scaling-up the process.

Membrane Bioreactors: A Promising Approach to Enhanced Enzymatic Hydrolysis of Cellulose

The depletion of fossil fuel resources and the negative impact of their use on the climate have resulted in the need for alternative sources of clean, sustainable energy. One available alternative, bioethanol, is a potential substitute for, or additive to, petroleum-derived gasoline. In the lignocellulose-to-bioethanol process, the cellulose hydrolysis step represents a major hurdle that hinders commercialization. To achieve economical production of bioethanol from lignocellulosic materials, the rate and yield of the enzymatic hydrolysis of cellulose, which is preferred over other chemically catalyzed processes, must be enhanced. To achieve this, product inhibition and enzyme loss, which are two major challenges, must be overcome. The implementation of membranes, which can permeate molecules selectively based on their size, offers a solution to this problem. Membrane bioreactors (MBRs) can enhance enzymatic hydrolysis yields and lower costs by retaining enzymes for repeated usage while permeating the products. This paper presents a critical discussion of the use of MBRs as a promising approach to the enhanced enzymatic hydrolysis of cellulosic materials. Various MBR configurations and factors that affect their performance are presented.

Biohydrogen Producing Facultative Anaerobic Bacteria from Different Anaerobic Sludge

This study aims to isolate and characterize efficient biohydrogen generating facultative anaerobic bacteria from various samples, viz., biogas plant (BGP), municipal sewage (MS), and dairy industry treatment plant (DTP). The physicochemical properties of various untreated anaerobic sludge samples reflect the anoxic state and appropriateness of the substrate for separating biohydrogen generating bacteria. The biohydrogen producing bacterial strains were separated from methanogens using the heat-treatment method. The facultative anaerobic bacterial load of heat-treated test samples was determined viz., 27.2±0.57×106 (BGP), 21.8±0.43×106 (MS), and 18.6±0.92×106 (DTP) CFU mL-1 (Colony forming unit), which decreased from the total anaerobic bacterial load of untreated anaerobic sludge viz., 32.1±0.28×106 (BGP), 42.2±0.16×106 (MS), and 34.7±0.12×106 (DTP) CFU mL-1. The 28 predominant bacterial isolates strains were isolated from the heat-treated test samples. All 28 bacterial strains were identified using microscopic and biochemical techniques. Biohydrogen producing potential bacterial strains were screened using the Hungate technique with glucose as a carbon source. Among them, 12 strains were capable of producing biohydrogen, among these 5 strains being excellent biohydrogen producers. Based on the16s rRNA molecular sequencing, the 5 selected biohydrogen generating organisms were authenticated as viz., Salmonella bongori (MZ636759), Escherichia coli (MZ636716), Staphylococcus hominis (MZ636713), Yersinia enterocolitica (OM009292), and Shewanella oneidensis (MZ636800). The gas composition study by GC-TCD in a fermentative medium shows that Shewanella oneidensis (MZ636800) could produce the best biohydrogen (111.4±8.3 mLH2/L), followed by Salmonella bongori (MZ636759) with 98.1±2.9 mL H2/L and Escherichia coli (MZ636716) with 86.7±6.2 mLH2/L.

Process study of ceramic membrane-coupled mixed-cell fermentation for the production of adenine

In order to solve the problems of high complexity, many by-products, high pollution and difficult extraction of the existing adenine production process, in this study, ceramic membrane-coupled mixed cell fermentation was used to produce adenine while reducing the synthesis of by-products and simplifying the production process of adenine. Nucleoside hydrolase (encoded by the rihC gene) was used to produce adenine by coordinated fermentation with the adenosine-producing bacterium Bacillus Subtilis XGL. The adenosine hydrolase (AdHy)-expressing strain Escherichia coli BL21-AdHy was successfully employed and the highest activity of the crude enzyme solution was found by orthogonal experiments at 170 W power, 42% duty cycle, and 8 min of sonication. The highest AdHy activity was found after 18 h of induction incubation. E. coli BL21-AdHy was induced for 18 h and sonicated under the above ultrasonic conditions and the resulting crude enzyme solution was used for co-fermentation of the strain and enzyme. Moreover, 15% (v/v) of the AdHy crude enzyme solution was added to fermentation of B. subtilis XGL after 35 h. Finally, the whole fermentation system was dialyzed using coupled ceramic membranes for 45 and 75 h, followed by the addition of fresh medium. In contrast, the AdHy crude enzyme solution was added after 35, 65, and 90 h of B. subtilis fermentation, with three additions of 15, 15, and 10% of the B. subtilis XGL fermentation system. The process was validated in a 5 L fermenter and 14 ± 0.25 g/L of adenine was obtained, with no accumulation of adenosine and d-ribose as by-products. The enzymatic activity of the AdHy crude solution treated with ultrasound was greatly improved. It also reduced the cellular activity of E. coli BL21-AdHy and reduced effects on bacterial co-fermentation. Membrane-coupled dialysis solved the problem of decreased yield due to poor bacterial survival and decreased viability, and eliminated inhibition of the product synthesis pathway by adenosine. The batch addition of crude enzyme broth allowed the continuous conversion of adenosine to adenine. This production method provides the highest yield of biologically produced adenine reported to date, reduces the cost of adenine production, and has positive implications for the industrial production of adenine by fermentation. And it provides a reference for producing other high-value-added products made by fermentation.

Synthesis and Comparative Studies of Glucose Oxidase Immobilized on Fe3O4 Magnetic Nanoparticles Using Different Coupling Agents

Squaric acid (SA) is a compound with potential to crosslink biomacromolecules. Although SA has become over the last years a well-known crosslinking agent as a result of its good biocompatibility, glutaraldehyde (GA), a compound with proven cytotoxicity is still one of the most used crosslinkers to develop nanomaterials. In this regard, the novelty of the present study consists in determining whether it may be possible to substitute GA with a new bifunctional and biocompatible compound, such as SA, in the process of enzyme immobilization on the surface of magnetic nanoparticles (MNPs). Thus, a direct comparison between SA- and GA-functionalized magnetic nanoparticles was realized in terms of physico-chemical properties and ability to immobilize catalytic enzymes. The optimal conditions of the synthesis of the two types of GOx-immobilized MNPs were described, thus emphasizing the difference between the two reagents. Scanning Electron Microscopy and Dynamic Light Scattering were used for size, shape and colloidal stability characterization of the pristine MNPs and of those coupled with GOx. Binding of GOx to MNPs by using GA or SA was confirmed by FT-IR spectroscopy. The stability of the immobilized and free enzyme was investigated by measuring the enzymatic activity. The study confirmed that the resulting activity of the immobilized enzyme and the optimization of enzyme immobilization depended on the type of reagent used and duration of the process. The catalytic performance of immobilized enzyme was tested, revealing that the long-term colloidal stability of SA-functionalized MNPs was superior to those prepared with GA. In conclusion, the SA-functionalized bioconjugates have a better potential as compared to the GA-modified nanosystems to be regarded as catalytic nanodevices for biomedical purposes such as biosensors.

Magnetic cross-linked enzyme aggregate based on ionic liquid modification as a novel immobilized biocatalyst for phytosterol esterification

Novel immobilized enzyme CRL-FIL-CLEAs@Fe3O4 with enhanced activities and stabilities was successfully prepared by a cross-linked lipase aggregate method for phytosterol esterification.

Integrated strategies for enzyme assisted extraction of bioactive molecules: A review

Conventional methods of extracting bioactive molecules are gradually losing pace due to their numerous disadvantages, such as product degradation, lower efficiency, and toxicity. Thus, in light of the rising demand for these bioactive, enzymes have garnered much attention for their efficiency in extraction. However, enzyme-assisted extraction is also plagued with a high capital cost that cannot justify the extraction yields obtained. In order to mitigate these problems, enzyme-assisted extraction can be consorted with non-conventional methods. This review includes current progress concerning the combined approaches while converging the recent advancements in the field that outperformed conventional extraction processes. It also highlights the design of biocatalyst and key parameters involved in the effective extraction of bioactive molecules. An integrated approach for efficiently extracting polyphenols, essential oils, pigments, and vitamins has been comprehensively reviewed. Furthermore, the different immobilization strategies have been discussed for large-scale implementation of enzymes for extraction. The integration of advanced non-conventional methods with enzyme-assisted extraction will open new avenues to enhance the overall extraction efficiency.

Immobilization of L-asparaginase on magnetic nanoparticles: Kinetics and functional characterization and applications

L-asparaginase shows great potential as a food enzyme to reduce acrylamide formation in fried and baked products. But for food applications, enzymes must be stable at high temperatures and have higher catalytic efficiency. These desirable characteristics are conferred by the immobilization of enzymes on a suitable matrix. The present study aimed to immobilize the L-asparaginase enzyme on magnetic nanoparticles to reduce acrylamide content in the food system. Immobilized preparations were characterized using SEM, TEM, FTIR, UV-spectrometry, and XRD diffraction analyses. These nanoparticles enhanced the thermal stability of the enzyme up to four-fold at 70 °C compared to the free enzyme. Kinetic parameters exhibited an increase in V_max, K_m, and catalytic efficiency by ~ 38% than the free counterpart. The immobilized preparations were reusable for up to five cycles. Moreover, their application in the pre-treatment coupled with blanching of potato chips led to a significant reduction (greater than 95%) of acrylamide formation.

Current perspective on production and applications of microbial cellulases: a review

The potential of cellulolytic enzymes has been widely studied and explored for bioconversion processes and plays a key role in various industrial applications. Cellulase, a key enzyme for cellulose-rich waste feedstock-based biorefinery, has increasing demand in various industries, e.g., paper and pulp, juice clarification, etc. Also, there has been constant progress in developing new strategies to enhance its production, such as the application of waste feedstock as the substrate for the production of individual or enzyme cocktails, process parameters control, and genetic manipulations for enzyme production with enhanced yield, efficiency, and specificity. Further, an insight into immobilization techniques has also been presented for improved reusability of cellulase, a critical factor that controls the cost of the enzyme at an industrial scale. In addition, the review also gives an insight into the status of the significant application of cellulase in the industrial sector, with its techno-economic analysis for future applications. The present review gives a complete overview of current perspectives on the production of microbial cellulases as a promising tool to develop a sustainable and greener concept for industrial applications.

Enzyme catalysis coupled with artificial membranes towards process intensification in biorefinery- a review

In this review, for the first time, the conjugation of the major types of enzymes used in biorefineries and the membrane processes to develop different configurations of MBRs, was analyzedfor the production of biofuels, phytotherapics and food ingredients. In particular, the aim is to critically review all the works related to the application of MBR in biorefinery, highlighting the advantages and the main drawbacks which can interfere with the development of this system at industrial scale. Alternatives strategies to overcome main limits will be also described in the different application fields, such as the use of biofunctionalized magnetic nanoparticles associated with membrane processes for enzyme re-use and membrane cleaning or the membrane fouling control by the use of integrated membrane process associated with MBR.

Cellulose-deconstruction potential of nano-biocatalytic systems: A strategic drive from designing to sustainable applications of immobilized cellulases

Nanostructured materials along with an added value of polymers-based support carriers have gained high interest and considered ideal for enzyme immobilization. The recently emerged nanoscience interface in the form of nanostructured materials combined with immobilized-enzyme-based bio-catalysis has now become research and development frontiers in advance and applied bio-catalysis engineering. With the involvement of nanoscience, various polymers have been thoroughly developed and exploited to nanostructured engineer constructs as ideal support carriers/matrices. Such nanotechnologically engineered support carriers/matrix possesses unique structural, physicochemical, and functional attributes which equilibrate principal factors and strengthen the biocatalysts efficacy for multipurpose applications. In addition, nano-supported catalysts are potential alternatives that can outstrip several limitations of conventional biocatalysts, such as reduced catalytic efficacy and turnover, low mass transfer efficiency, instability during the reaction, and most importantly, partial, or complete inhibition/deactivation. In this context, engineering robust and highly efficient biocatalysts is an industrially relevant prerequisite. This review comprehensively covered various biopolymers and nanostructured materials, including silica, hybrid nanoflower, nanotubes or nanofibers, nanomembranes, graphene oxide nanoparticles, metal-oxide frameworks, and magnetic nanoparticles as robust matrices for cellulase immobilization. The work is further enriched by spotlighting applied and industrially relevant considerations of nano-immobilized cellulases. For instance, owing to the cellulose-deconstruction features of nano-immobilized cellulases, the applications like lignocellulosic biomass conversion into industrially useful products or biofuels, improved paper sheet density and pulp beat in paper and pulp industry, fruit juice clarification in food industry are evident examples of cellulases, thereof are discussed in this work.

Site-directed lysine modification of xylanase for oriented immobilization onto silicon dioxide nanoparticles

Enhanced covalent immobilization of xylanase from Chaetomium globosum (XylCg) onto SiO₂ nanoparticles was achieved by the modification of surface residues. The mutation of surface residues to lysine by site-directed mutagenesis increased the immobilization efficiency (IE) and immobilization yield (IY). The immobilized mutant XylCg (N172K-H173K-S176K-K133A-K148A) exhibited an IY of 99.5% and IE of 135%, which were 1.8- and 4.3-fold higher than immobilized wildtype (WT). Regarding the catalytic properties, the k_cat and k_cat/K_m values were 1850 s^-1 and 2030 mL mg^-1 s^-1 for the immobilized mutant, and 331 s^-1 and 404 mL mg^-1 s^-1 for the immobilized WT, respectively. Additionally, the immobilized mutant exhibited four times higher thermal stability than the immobilized WT at 60 °C. These results suggest that surface-mutated lysine residues confer good stability and orientation on the support matrix, thus improving the overall performance of xylanase.

Robust and recyclable magnetic nanobiocatalysts for extraction of anthocyanin from black rice

Anthocyanins, which are natural pigments and nutraceuticals, can be extracted from plant materials using enzyme-assisted methods. However, the enzymes used are often expensive, fragile, and hard to recover/reuse. In this study, cellulase and α-amylase were immobilized on amino-functionalized magnetic nanoparticles to prepare a magnetic nanobiocatalyst. The enzymes in this nanobiocatalyst exhibited higher stability and greater catalytic activity than free enzymes, including good thermal stability (50 to 70℃) and pH stability (pH 4.5-7.5). Nanobiocatalyst efficacy was demonstrated by extracting anthocyanins from black rice, with a maximum yield of 266 mg anthocyanin/100 g black rice obtained. After six reuse cycles, cellulase and α-amylase retained around 70% and 64% of their activity, respectively. Immobilization also increased their reusability. In summary, a novel magnetic nanobiocatalyst was developed for extracting anthocyanins from black rice, which may also have other applications within the food industry.

Preparation of regenerable magnetic nanoparticles for cellulase immobilization: Improvement of enzymatic activity and stability

To obtain regenerable magnetic nanoparticles, triethoxy(3-isocyanatopropyl)silane and iminodiacetic acid (IZ) were used as the starting material and immobilized on Fe₃ O₄ nanoparticles. Copper ions (Cu²⁺ ions) were loaded on the Fe-IZ nanoparticles and used for cellulase immobilization. The support was characterized by spectroscopic methods (FTIR, NMR) and thermogravimetric analysis, transmission electron microscopy, scanning electron microscope, X-ray diffraction, energy dispersive X-ray analysis, and vibrating sample magnetometer techniques. As a result of experiments, the amount of protein bound to immobilized cellulase (Fe-IZ-Cu-E) and cellulase activity was found to be 33.1 mg/g and 154 U/g at pH 5, 50°C, for 3 h. The results indicated that the free cellulase had kept only 50% of its activity after 2 h, while the Fe-IZ-Cu-E was observed to be around 77%, at 60°C. It was found that the immobilized cellulase maintained 93% of its initial catalytic activity after its sixth use. Furthermore, the Fe-IZ-Cu-E retained about 75% of its initial activity after 28 days of storage. To reuse the support material (Fe-IZ-Cu), it was regenerated by thorough washing with ammonia or imidazole.

Rapid screening and separation of active compounds against α-amylase from Toona sinensis by ligand fishing and high-speed counter-current chromatography

In the present study, an efficient method based on ligand fishing and high-speed counter-current chromatography (HSCCC) was established to screen, enrich and separate the active components with the α-amylase inhibitory activity from a traditional dish Toona sinensis. The active components were screened from T. sinensis by ligand fishing using the magnetic immobilized α-amylase prepared through solvothermal and crosslinking methods. HSCCC was used to separate the target compound according to the K value. As a result, a potential active compound 1,2,3,4,6-penta-O-galloyl-β-d-glucose and a non-target compound quercetin-3-O-α-L-rhamnopyranoside were separated and identified. In-vitro experiments indicated that 1,2,3,4,6-penta-O-galloyl-β-d-glucose had the activity against α-amylase and the IC₅₀ value was 93.49 ± 0.80 μg/mL which was higher than that of the non-target compound. The result further confirmed the molecular fishing effect of magnetic immobilized α-amylase. The present study can not only find and separate the hypoglycemic substances in T. sinensis quickly and effectively, but also can provide a new approach for the study of natural active components.

Laccase immobilized peroxidase mimicking magnetic metal organic frameworks for industrial dye degradation

In the present work, laccase was successfully immobilized in peroxidase mimicking magnetic metal organic frameworks (MMOFs) within 30 min using a facile approach. The integration of magnetic nanoparticles during synthesis significantly eases the separation of prepared biocatalyst using an external magnet. The immobilization of laccase was confirmed using different characterization techniques. The laccase@MMOFs found spherical in nature with an average particle size below 100 nm. The synthesized laccase embedded framework exhibits supermagnetic property with the saturation magnetization (Ms) of 34.12 emu/gm. The prepared bio-metallic frameworks maintain high surface area and thermal stability. The laccase@MMOFs was successfully exploited for the degradation of industrial dyes in batch and continuous mode with an average degradation efficiency of 95%. The prepared laccase structure had an excellent recyclability retaining upto 89% residual activity upto 10^th cycle and can be stored at room temperature upto 30 days without any significant loss of activity.

One pot clarification and debittering of grapefruit juice using co-immobilized enzymes@chitosanMNPs

In the present work, enzymes pectinase and naringinase were simultaneously co-immobilized on an eco-friendly chitosan coated magnetic nanoparticles (chitosanMNPs) by cross-linking using chitosan as a macro-molecular cross-linker. The maximum activity recovery of both enzymes in the co-immobilized form was obtained at chitosanMNPs to enzymes ratio of 1:3, 3% cross-linker concentration and 150 min cross-linking time. The synthesized MNPs before and after co-immobilization were characterized using different techniques. The prepared biocatalyst was found spherical with an average size below 200 nm and showed supermagnetic property with saturation magnetization of 38.28 emu/g. The optimum pH and temperature of both enzymes in co-immobilized form was found at 5.5 and 65 °C. The prepared biocatalyst exhibited an improved thermal stability with 1.8-fold increase in the half-life. The secondary structural analysis revealed that, prepared co-immobilized biocatalyst undergone changes in the conformational and structural rigidity due to macro-molecular cross-linker. The co-immobilized biocatalysts were evaluated for one pot clarification and debittering of grapefruit juice and found ~52% reduction in turbidity and ~85% reduction in the naringin content. The co-immobilized enzymes were recycled up to 7^th cycle and can be easily stored at room temperature for 30 days retaining up to 64% and 86% residual activities respectively.

Advances in nanomaterials induced biohydrogen production using waste biomass

Recent advances on biohydrogen production using different types of waste biomass with the implementation of nanomaterials are summarized. Inspired by exceptional physicochemical and catalytic properties of nanomaterials, the present review focuses on several approaches including impact of nanomaterials on cellulosic biohydrogen production, possible pretreatment technology, as well as improved enzyme & sugar production in order to enhance the biohydrogen yield. Particularly, impacts of nanomaterial are elaborated in detail on different pathways of biohydrogen production (e.g. dark fermentation, photo-fermentation and hybrid-fermentation) using variety of waste biomass. Additionally, emphases are made on the feasibility of nanomaterials for making the biohydrogen production process more economical and sustainable and hence to develop advanced techniques for biohydrogen production using waste biomass.

Ultrasound-Assisted Extraction for the Recovery of Carotenoids from Guava's Pulp and Waste Powders

In this work, lycopene- and β-carotene-rich extracts were obtained from guava's pulp and waste powders using maceration (ME), ultrasonic bath (BUAE, 25 °C for 30 min), and ultrasonic probe (PUAE, 25 °C for 5 min). Extracts were evaluated for total carotenoid content, antioxidant capacity, color, and lycopene and β-carotene content by HPLC-DAD. Bath-type ultrasound-assisted extraction (BUAE) was the best technique to obtain lycopene from guava pulp (135.0 mg 100 g^-1) and waste (76.64 mg 100 g^-1), followed by ME (pulp = 107.6, waste = 43.57 mg 100 g^-1), and PUAE (pulp = 44.19, waste = 33.83 mg 100 g^-1). The total carotenoid content positively affected the extracts' antioxidant capacity. Dehydration of guava fractions showed to be an efficient method to increase carotenoid availability. This is the first work to report the recovery of carotenoids from guava by ultrasonic extraction. Furthermore, this method has shown to be a suitable approach to reduce extraction time and solvent use. These extracts could be further applied to lipid-rich foods as a natural antioxidant and/or as an ingredient in the development of functional foods.

Magnetic nanoparticles-based lactate dehydrogenase microreactor as a drug discovery tool for rapid screening inhibitors from natural products

Lactate dehydrogenase (LDH), catalyzing the conversion of pyruvate to lactate during glycolysis, is overexpressed in cancer cells. LDH inhibitors are a promising approach for the treatment of cancer. But up till now, there is limited method for rapid screening of LDH inhibitors. Herein, the use of LDH functionalized magnetic nanoparticles as a drug discovery tool for the selective enrichment of LDH potential inhibitors from natural products was firstly reported in this study. Firstly, LDH was immobilized onto the surface of amino-modified magnetic nanoparticles via covalent binding. In order to obtain the maximum enzyme activity, the immobilization conditions including pH, time and LDH concentration were optimized. The amount of LDH immobilized on MNPs was about 49 μg enzyme/mg carrier under the optimized conditions. Subsequently, the ligand fishing assay was performed to validate the specificity and selectivity of immobilized LDH using a model mixture, which consisted of galloflavin, chlorogenic acid and verbascoside. Finally, the immobilized LDH approach combined with ultra-high performance liquid chromatography-tandem mass spectrometry technique (UHPLC-MS/MS) was applied to screen potential LDH inhibitors from two anthraquinone-rich natural products (Rhubarb and Polygonum cuspidatum). Nine and six compounds were identified from Rhubarb and Polygonum cuspidatum extracts respectively, of which three compounds were common to both. Our results have proven that LDH functionalized magnetic nanoparticles have a significant prospect for drug discovery from complex matrices.

Enzyme activity of waste activated sludge extracts

Wastewater treatment and generated biological sludge provide an alternative source of enzymes to conventional industrial production methods. Here, we present a protocol for extracting enzymes from activated sludge using ultrasonication and surfactant treatment. Under optimum conditions, ultrasound disruption of activated sludge gave recovery rates of protease and cellulase enzymes equivalent to 63.1% and ∼100%, respectively. The extracting of enzymes from activated sludge represents a potentially significant, high-value, resource recovery option for biological sludge generated by municipal wastewater treatment.

Refolding of thermally denatured cholesterol oxidases by magnetic nanoparticles

Proteins are prone to unfolding and subsequent denaturation by changes in temperature, pH and other harsh conditions. Nanoparticles act as artificial 'chaperones' due to favourable orientation of the proteins on their scaffold which prevents aggregation and reconfigures denatured proteins into their native functional state. In the present study, thermal denaturation of Cholesterol oxidases from Pseudomonas aeruginosa PseA, Rhodococcus erythropolis MTCC 3951 and Streptomyces sp. were studied at temperatures 50-70 °C. Further, these thermally denatured proteins were refolded using functionalized Magnetic Iron (II, III) oxide nanoparticles which was confirmed using DLS, Zeta Potential Measurements, fluorescence and CD spectroscopy. The refolded proteins were found to regain their secondary structure and activity to a great extent.

Stabilization of cutinase by covalent attachment on magnetic nanoparticles and improvement of its catalytic activity by ultrasonication

This paper reports on stabilization of serine cutinase activity by immobilizing it through cross linking with glutaraldehyde on magnetic nanoparticles (Fe-NPs) and intensification of catalytic activity by ultrasonic treatment. The optimum parameters were cross linking with 10.52 mM glutaraldehyde for 90 min using 1:2 (w/w) ratio of enzyme:Fe-NPs. The characterization of cutinase-Fe-NPs was done by different instrumental analysis. Ultrasonic power showed a beneficial effect on the activity of free and immobilized cutinase at 5.76 and 7.63 W, respectively, after 12 min. Immobilization and ultrasonic treatment led to increments in kinetic parameters (K_m and V_max) along with noticeable changes in the secondary structural fractions of cutinase. Cutinase-Fe-NPs showed augmented pH (4-8) and thermal stability (40-60 °C). Considerably higher thermal inactivation kinetic constants (k_d, t_1/2 and D-value) and thermodynamic constants (E_d, ΔH°, ΔG° and ΔS°) highlighted superior thermostability of cutinase-Fe-NPs. Cutinase-Fe-NPs and ultrasound treated cutinase-Fe-NPs retained 61.88% and 38.76% activity during 21-day storage, and 82.82 and 80.69% activity after fifth reusability cycle, respectively.

Enzyme Immobilization on Metal-Organic Framework (MOF): Effects on Thermostability and Function

MOFs are porous materials with adjustable porosity ensuing a tenable surface area and stability. MOFs consist of metal containing joint where organic ligands are linked with coordination bonding rendering a unique architecture favouring the diverse applications in attachment of enzymes, Chemical catalysis, Gases storage and separation, biomedicals. In the past few years immobilization of soluble enzymes on/in MOF has been the topic of interest for scientists working in diverse field. The activity of enzyme, reusability, storage, chemical and thermal stability, affinity with substrate can be greatly improved by immobilizing of enzyme on MOFs. Along with improvement in enzymes properties, the high loading of enzyme is also observed while using MOFs as immobilization support. In this review a detail study of immobilization on/in Metalorganic Frameworks (MOFs) have been described. Furthermore, strategies for the enzyme immobilization on MOFs and resulting in improved catalytic performance of immobilized enzymes have been reported.

Recent Advances of Cellulase Immobilization onto Magnetic Nanoparticles: An Update Review

Cellulosic enzymes, including cellulase, play an important role in biotechnological processes in the fields of food, cosmetics, detergents, pulp, paper, and related industries. Low thermal and storage stability of cellulase, presence of impurities, enzyme leakage, and reusability pose great challenges in all these processes. These challenges can be overcome via enzyme immobilization methods. In recent years, cellulase immobilization onto nanomaterials became the focus of research attention owing to the surface features of these materials. However, the application of these nanomaterials is limited due to the efficacy of their recovery process. The application of magnetic nanoparticles (MNPs) was suggested as a solution to this problem since they can be easily removed from the reaction mixture by applying an external magnet. Recently, MNPs were extensively employed for enzyme immobilization owing to their low toxicity and various practical advantages. In the present review, recent advances in cellulase immobilization onto functionalized MNPs is summarized. Finally, we discuss enhanced enzyme reusability, activity, and stability, as well as improved enzyme recovery. Enzyme immobilization techniques offer promising potential for industrial applications.

Intensified approach for desulfurization of simulated fuel containing thiophene based on ultrasonic flow cell and oxidizing agents

Intensified desulfurization of simulated crude fuel containing thiophene has been investigated using ultrasonic flow cell in combination with oxidizing agents such as peracetic acid, hydrogen peroxide (H₂O₂) and Fenton reagent at ambient conditions. The effect of thiophene loading, recirculation flow rate and the oxidant loading on the extent of desulfurization has been studied at 1 L capacity. Combination of ultrasound and hydrogen peroxide at optimized loading of 8% resulted in higher extent of desulfurization (38%) as compared to only ultrasound (17%). Higher degree of enhancement in extent of desulfurization (57% as the actual value) was observed for combination of ultrasound and peracetic acid at loading of 10%. Significant increase in extent of desulfurization was obtained for the combination of ultrasound and Fenton reagent (2 g/L FeSO₄ + 10% H₂O₂) with actual extent being 87%. The conventional approaches of only hydrogen peroxide and only Fenton without ultrasound resulted in much lower extent of desulfurization as 22 and 40% respectively confirming the synergism for the combined process involving ultrasound. Maximum desulfurization extent as 96% was obtained for the approach of ultrasound combined with Fenton reagent at 2 g/L of FeSO₄ and 15% H₂O₂ addition in three stages and 80 min of treatment time. The analysis of treated samples using HPLC spectra revealed that no other by-products or unwanted chemical species were formed during the treatment. The process intensification benefits have been clearly established in terms of much higher extent of desulfurization for combined approaches with the final sulfur content below minimum limit (5 ppm) whereas most of the conventional desulfurization approaches (without ultrasound) resulted in sulfur retention up to 10 ppm in final treated fuel.

Magnetic cross-linked enzyme aggregates of acrylamidase from Cupriavidus oxalaticus ICTDB921 for biodegradation of acrylamide from industrial waste water

Acrylamidase from Cupriavidus oxalaticus ICTDB921 was immobilized on magnetic nanoparticles (MNPs) for degradation of acrylamide (a group 2A carcinogen and an environmental contaminant) from industrial waste water. Acrylamidase-MNPs were prepared (maximum recovery ∼94%) at optimized process parameters viz. 1.5:1 (v/v) of acetone: crude acrylamidase/5 mM of glutaraldehyde/90 min/1.5:1 of enzyme: MNP ratio. MNPs and acrylamidase-MNPs were characterized by particle size analysis, FTIR, XRD, SEM and vibrating sample magnetometer. Acrylamidase-MNPs showed a shift in optimum pH (8-8.5) and temperature (60-65 °C) with higher pH/thermal stability vis-à-vis free enzyme. A significant increase in kinetic constants, thermal inactivation constants and thermodynamic parameters were noted for acrylamidase-MNPs. A complete degradation of acrylamide ∼2100 mg/L was achieved in industrial waste water under optimized conditions for batch process and the kinetics was best represented by Haldane model. Acrylamidase-MNPs retained >80% of its initial activity after 4 cycles for both pure acrylamide and industrial waste water.

Asparaginase conjugated magnetic nanoparticles used for reducing acrylamide formation in food model system

Acrylamide is a potent carcinogen and neurotoxin formed by the Maillard reaction when l-asparagine reacts with starch at high temperature. It is formed in food materials mainly deep fried and bakery products. Enzymatic pretreatment of these food products with asparaginase enzyme leads to reduction in acrylamide. However, enzymatic process is quite expensive due to high cost, low catalytic efficiency as well as problem with enzyme reusability. Present work deals with these problems by exploring l-asparaginase from Bacillus aryabhattai. Asparaginase enzyme was immobilized on APTES modified magnetic nanoparticles. It was found to be more than three-fold increase their thermal stability from free enzyme and retained 90% activity after fifth cycle. The immobilized enzyme also showed better affinity towards its substrate. During pretreatment of asparagine in a starch-asparagine food model system and it was clearly demonstrated that asparaginase nanoconjugates had reduced the formation of acrylamide by more than 90% within 30 min.