Immobilization of β-Galactosidases on Magnetic Nanocellulose: Textural, Morphological, Magnetic, and Catalytic Properties

Preparation and applications of magnetic nanocellulose composites: A review

Cellulose is the most abundant biomass material in the world. Magnetic nanoparticles can be used as reinforcing materials to give cellulose more functions due to their unique magnetism. According to the dispersion stability of nanocellulose, magnetic nanocellulose is divided into homogeneous preparation and heterogeneous preparation. In addition, the directional arrangement of nanocellulose by external magnetic field is also a way of cellulose functionalization. The current preparation of magnetic nanocellulose is mainly based on heterogeneous preparation. Magnetic nanofiber cellulose has great application potential in the field of biomedicine and sewage purification due to its special magnetic properties. It can also be applied to sensors, food packaging and other fields. In this paper, the preparation methods of magnetic nanocellulose and its physical magnetism are introduced. Then, the application of magnetic nanocellulose in different fields is reviewed. Finally, the current challenges of magnetic nanocellulose are summarized and the future development trend is prospected.

Fabrication of chia gum based covalent immobilizers

Chia gum (CG) films were processed with polyethylene-imine (PEI) and glutaraldehyde (GA) in order to in-solubilize them and transform them into covalent immobilizers. These immobilizers were exploited to immobilize protease (PR) and β-D-galactosidase (β-GAL). Accordingly, the GA/PEI processing was individually honed for both enzymes via Box-Behnken Design. In case of β-GAL, it was optimal to process the CG with 5.43 % PEI at pH 8.32 followed by 6.02 % GA. On the other hand, optimal PR immobilizers were processed with 1.5 % PEI at pH 9.52 followed by 10 % GA solution. The proficiency of the β-GAL and PR immobilizers were then compared with respect to their granted operational stabilities. The immobilized β-GAL (iβ-GAL) presented much enhanced operational stability as it preserved 93.29 % of its inceptive activity during its 14th run. Accordingly, the GA/PEI/CG β-GAL immobilizers were further inspected via FTIR, EDX, and SEM. The iβ-GAL pH and activity profiles were also inspected and compared to those of its free cognate. Moreover, iβ-GAL exhibited enhanced thermal stability where it presented larger t1/2, D-values, and ΔG than did its free cognate. The iβ-GAL also presented enhanced storage, solvent and heavy-metals stabilities. Finally, the iβ-GAL successfully degraded lactose in whey permeate for 6 consecutive 24 h cycles.

Covalent Lysozyme Immobilization on Enzymatic Cellulose Nanocrystals

Nanostructured materials represent promising substrates for biocatalyst immobilization and activation. Cellulose nanocrystals (CNCs), accessible from waste and/or renewable sources, are sustainable and biodegradable, show high specific surface area for anchoring a high number of enzymatic units, and high thermal and mechanical stability. In this work, we present a holistic enzyme-based approach to functional antibacterial materials by bioconjugation between the lysozyme from chicken egg white and enzymatic cellulose nanocrystals. The neutral CNCs were prepared by endoglucanase hydrolysis from Avicel. We explore the covalent immobilization of lysozyme on enzymatic CNCs and on their TEMPO oxidized derivatives (TO-CNCs), comparing immobilization yields, material properties, and enzymatic activities. The materials were characterized by X-ray diffractometry (XRD), attenuated total reflectance Fourier Transform infrared spectroscopy (ATR-FTIR), bicinchoninic acid (BCA) assay, field-emission scanning electron microscopy (FE-SEM) and dynamic light scattering (DLS). We demonstrate the higher overall efficiency of the immobilization process carried out on TO-CNCs, based on the success of covalent bonding and on the stability of the isolated bioconjugates.

Grafted calcium pectinate-whey protein isolate covalent immobilizers: Optimization, kinetics, thermodynamics, and application

Whey protein isolate (WPI) was incorporated within calcium pectinate (CPT) beads in order to boost their anionic qualities and meliorate their glutaraldehyde (GA)-polyethyleneimine (PEI) grafting process. The Box-Behnken Design (BBD) verified that WPI inclusion significantly raised the GA-PEI-CPT-WPI beads immobilized β-D-galactosidase (iβ-GLD) activity. The BBD also revealed the optimal settings for WPI concentration, PEI pH, PEI concentration, and GA concentration, which were 2.91 %, 10.8, 3.5 %, and 2.24 %, respectively. The GA-PEI-CPT-WPI beads grafting process was scrutinized via FTIR, EDX, and SEM. The optimal GA-PEI-CPT-WPI immobilizers provided fine β-GLD immobilization efficiencies, which reached up to 65.28 %. The free and GA-PEI-CPT-WPI iβ-GLDs pH and temperature profiles were scrutinized. It was also unveiled that the thermal stability of the iβ-GLD surpassed that of its free compeer as it provided lesser kd and ΔS values and larger t1/2, D-values, Ed, ΔH, and ΔG values. Furthermore, the iβ-GLD provided 92.00±3.39 % activity after 42 storage days, which denoted its fine storage stability. The iβ-GLD short duration (15 min) operational stability was also inspected, and 82.70±0.78 % activity was provided during the fifteenth degradation run. Moreover, the iβ-GLD long duration (24 h) operational stability was inspected while degrading the lactose of buffered lactose solution (BLS) and cheese whey (CW). It was unveiled that 81.86±0.96 % and 73.58±2.24 % of the initial glucose were detected during the sixth degradation runs, respectively.

Lactose hydrolysis in packed-and fluidized-bed reactors using a recombinant β-galactosidase immobilized on magnetic core-shell capsules

The objective of this study was to develop a bioprocess for lactose hydrolysis in diverse dairy matrices, specifically skim milk and cheese whey, utilizing column reactors employing a core-shell enzymatic system featuring β-galactosidase fused to a Cellulose Binding Domain (CBD) tag (β-galactosidase-CBD). The effectiveness of reactor configurations, including ball columns and toothed columns operating in packed and fluidized-bed modes, was evaluated for catalyzing lactose hydrolysis in both skim milk and cheese whey. In a closed system, these reactors achieved lactose hydrolysis rates of approximately 50% within 5 h under all evaluated conditions. Considering the scale of the bioprocess, the developed enzymatic system was capable of continuously hydrolyzing 9.6 L of skim milk while maintaining relative hydrolysis levels of approximately 50%. The biocatalyst, created by immobilizing β-galactosidase-CBD on magnetic core-shell capsules, exhibited exceptional operational stability, and the proposed bioprocess employing these column reactors showcases the potential for scalability.

Magnetic core-shell cellulose system for the oriented immobilization of a recombinant β-galactosidase with a protein tag

The objective of this study was to immobilize a recombinant β-galactosidase (Gal) tagged with a cellulose-binding domain (CBD) onto a magnetic core-shell (CS) cellulose system. After 30 min of reaction, 4 U/capsule were immobilized (CS@Gal), resulting in levels of yield and efficiency exceeding 80 %. The optimal temperature for β-galactosidase-CBD activity increased from 40 to 50 °C following oriented immobilization. The inhibitory effect of galactose decreased in the enzyme reactions catalyzed by CS@Gal, and Mg2+ increased the immobilized enzyme activity by 40 % in the magnetic CS cellulose system. The relative enzyme activity of the CS@Gal was 20 % higher than that of the soluble enzyme activity after 20 min at 50 °C. The CS support and CS@Gal capsules exhibited an average size of 8 ± 1 mm, with the structure of the shell (alginate-pectin-cellulose) enveloping and isolating the magnetic core. The immobilized β-galactosidase-CBD within the magnetic CS cellulose system retained ∼80 % of its capacity to hydrolyze lactose from skim milk after 10 reuse cycles. This study unveils a novel and promising support for the oriented immobilization of recombinant β-galactosidase using a magnetic CS system and a CBD tag. This support facilitates β-galactosidase reuse and efficient separation, consequently enhancing the catalytic properties of the enzyme.

Application of cellulosic materials as supports for single-step purification and immobilization of a recombinant β-galactosidase via cellulose-binding domain

This study aimed to develop single-step purification and immobilization processes on cellulosic supports of β-galactosidase from Kluyveromyces sp. combined with the Cellulose-Binding Domain (CBD) tag. After 15 min of immobilization, with an enzymatic load of 150 U/g_support, expressed activity values reached 106.88 (microcrystalline cellulose), 115.03 (alkaline nanocellulose), and 108.47 IU/g (acid nanocellulose). The derivatives produced were less sensitive to the presence of galactose in comparison with the soluble purified enzyme. Among the cations assessed (Na⁺, K⁺, Mg²⁺, and Ca²⁺), magnesium provided the highest increase in the enzymatic activity of β-galactosidases immobilized on cellulosic supports. Supports and derivatives showed no cytotoxic effect on the investigated cell cultures (HepG2 and Vero). Derivatives showed high operational stability in the hydrolysis of milk lactose and retained from 53 to 64% of their hydrolysis capacity after 40 reuse cycles. This study obtained biocatalyzers with promising characteristics for application in the food industry. Biocatalyzers were obtained through a low-cost one-step sustainable bioprocess of purification and immobilization of a β-galactosidase on cellulose via CBD.

Covalent Immobilization of Chondrostereum purpureum Endopolygalacturonase on Ferromagnetic Nanoparticles: Catalytic Properties and Biotechnological Application

Pectinases are widely used in a variety of industrial processes. However, their application is limited by low catalytic processivity, reduced stability, high cost, and poor re-use compatibility. These drawbacks may be overcome by enzyme immobilization with ferromagnetic nanoparticles, which are easily recovered by a magnetic field. In this work, an endopolygalacturonase from Chondrostereum purpureum (EndoPGCp) expressed in Pichia pastoris was immobilized on glutaraldehyde-activated chitosan ferromagnetic nanoparticles (EndoPGCp-MNP) and used to supplement a commercial enzyme cocktail. No significant differences in biochemical and kinetic properties were observed between EndoPGCp-MNP and EndoPGCp, although the EndoPGCp-MNP showed slightly increased thermostability. Cocktail supplementation with EndoPGCp-MNP increased reducing sugar release from orange wastes by 1.8-fold and showed a synergistic effect as compared to the free enzyme. Furthermore, EndoPGCp-MNP retained 65% of the initial activity after 7 cycles of re-use. These properties suggest that EndoPGCp-MNP may find applications in the processing of pectin-rich agroindustrial residues.

One-step purification of a recombinant beta-galactosidase using magnetic cellulose as a support: Rapid immobilization and high thermal stability

For the first time, this work reported the one-step purification and targeted immobilization process of a β-galactosidase (Gal) with the Cellulose Binding Domain (CBD) tag, by binding it to different magnetic cellulose supports. The process efficiency after β-galactosidase-CBD immobilization on magnetic cellulose-based supports showed values of approximately 90% for all evaluated enzymatic loads. Compared with free Gal, derivatives showed affinity values between β-galactosidase and the substrate 1.2 × higher in the lactose hydrolysis of milk. β-Galactosidase-CBD's oriented immobilization process on supports increased the thermal stability of the immobilized enzyme by up to 7 × . After 15 cycles of reuse, both enzyme preparations showed a relative hydrolysis percentage of 50% of lactose in milk. The oriented immobilization process developed for purifying recombinant proteins containing the CBD tag enabled the execution of both steps simultaneously and quickly and the obtention of β-galactosidases with promising catalytic characteristics for application in the food and pharmaceutical industries.

β-Galactosidase from Kluyveromyces lactis: Characterization, production, immobilization and applications - A review

A review on the enzyme β-galactosidase from Kluyveromyces lactis is presented, from the perspective of its structure and mechanisms of action, the main catalyzed reactions, the key factors influencing its activity, and selectivity, as well as the main techniques used for improving the biocatalyst functionality. Particular attention was given to the discussion of hydrolysis, transglycosylation, and galactosylation reactions, which are commonly mediated by this enzyme. In addition, the products generated from these processes were highlighted. Finally, biocatalyst improvement techniques are also discussed, such as enzyme immobilization and protein engineering. On these topics, the most recent immobilization strategies are presented, emphasizing processes that not only allow the recovery of the biocatalyst but also deliver enzymes that show better resistance to high temperatures, chemicals, and inhibitors. In addition, genetic engineering techniques to improve the catalytic properties of the β-galactosidases were reported. This review gathers information to allow the development of biocatalysts based on the β-galactosidase enzyme from K. lactis, aiming to improve existing bioprocesses or develop new ones.

Magnetic Nanoparticle-Containing Supports as Carriers of Immobilized Enzymes: Key Factors Influencing the Biocatalyst Performance

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes.

Synthesis of magnetic nanoparticles functionalized with histidine and nickel to immobilize His-tagged enzymes using β-galactosidase as a model

The aim of this study was to synthesize iron magnetic nanoparticles functionalized with histidine and nickel (Fe₃O₄-His-Ni) to be used as support materials for oriented immobilization of His-tagged recombinant enzymes of high molecular weight, using β-galactosidase as a model. The texture, morphology, magnetism, thermal stability, pH and temperature reaction conditions, and the kinetic parameters of the biocatalyst obtained were assessed. In addition, the operational stability of the biocatalyst in the lactose hydrolysis of cheese whey and skim milk by batch processes was also assessed. The load of 600 U_enzyme/g_support showed the highest recovered activity value (~50%). After the immobilization process, the recombinant β-galactosidase (HisGal) showed increased substrate affinity and greater thermal stability (~50×) compared to the free enzyme. The immobilized β-galactosidase was employed in batch processes for lactose hydrolysis of skim milk and cheese whey, resulting in hydrolysis rates higher than 50% after 15 cycles of reuse. The support used was obtained in the present study without modifying chemical agents. The support easily recovered from the reaction medium due to its magnetic characteristics. The iron nanoparticles functionalized with histidine and nickel were efficient in the oriented immobilization of the recombinant β-galactosidase, showing its potential application in other high-molecular-weight enzymes.

Cellulose supported magnetic nanohybrids: Synthesis, physicomagnetic properties and biomedical applications-A review

Cellulose and its forms are widely used in biomedical applications due to their biocompatibility, biodegradability and lack of cytotoxicity. It provides ample opportunities for the functionalization of supported magnetic nanohybrids (CSMNs). Because of the abundance of surface hydroxyl groups, they are surface tunable in either homogeneous or heterogeneous solvents and thus act as a substrate or template for the CSMNs' development. The present review emphasizes on the synthesis of various CSMNs, their physicomagnetic properties, and potential applications such as stimuli-responsive drug delivery systems, MRI, enzyme encapsulation, nucleic acid extraction, wound healing and tissue engineering. The impact of CSMNs on cytotoxicity, magnetic hyperthermia, and folate-conjugates is highlighted in particular, based on their structures, cell viability, and stability. Finally, the review also discussed the challenges and prospects of CSMNs' development. This review is expected to provide CSMNs' development roadmap in the context of 21st-century demands for biomedical therapeutics.

Production of beta-galactosidase fused to a cellulose-binding domain for application in sustainable industrial processes

This study aimed to produce and characterize a recombinant Kluyveromyces sp. β-galactosidase fused to a cellulose-binding domain (CBD) for industrial application. In expression assays, the highest enzymatic activities occurred after 48 h induction on Escherichia coli C41(DE3) strain at 20 °C in Terrific Broth (TB) culture medium, using isopropyl β-d-1-thiogalactopyranoside (IPTG) 0.5 mM (108.77 U/mL) or lactose 5 g/L (93.10 U/mL) as inducers. Cultures at bioreactor scale indicated that higher product yield values in relation to biomass (2000 U/g) and productivity (0.72 U/mL.h) were obtained in culture media containing higher protein concentration. The recombinant enzyme showed high binding affinity to nanocellulose, reaching both immobilization yield and efficiency values of approximately 70% at pH 7.0 after 10 min reaction. The results of the present study pointed out a strategy for recombinant β-galactosidase-CBD production and immobilization, aiming toward the application in sustainable industrial processes using low-cost inputs.

Magnetic graphene oxide nanocomposites as an effective support for lactase immobilization with improved stability and enhanced photothermal enzymatic activity

Magnetic graphene oxide-immobilized lactase with high loading capacity, improved stabilities, and photothermal enhancement of activity has been reported.

Analytical Determination of the Optimal Feed Temperature for Hydrogen Peroxide Decomposition Process Occurring in Bioreactor with a Fixed-Bed of Commercial Catalase

The hydrogen peroxide-immobilized commercial catalase system was chosen to estimate the optimal feed temperature (OFT) for fixed-bed reactor (FXBR). This feed temperature was obtained based on analytical solution by maximizing the time-averaged substrate conversion under a constant feed flow rate and temperature constraints. In calculations a set of partial differential equations describing the conservation equation for fixed-bed reactor, assuming plug flow and kinetic equation for the rate of enzyme parallel deactivation was taken into account. The model is based on kinetic, and mass-transfer parameters estimated previously in a real decomposition process of hydrogen peroxide (HP). The simulation showed that the OFT is strongly dependent on hydrogen peroxide feed concentration, feed flow rate and diffusional resistances expressed by biocatalyst global effectiveness factor. It has been shown that the more significant diffusional resistances and the higher HP conversions are, the higher the optimal feed temperature is. The calculated values of the OFT were verified with the experimental results obtained in the model reactor at selected values of the feed flow rate. Presented analysis poses a significant simplification in a numerical computational procedure and can be very useful for engineers to select the temperature condition at which bioreactor productivity is expected to be maximal.