Enhancing biocatalyst performance through immobilization of lipase (Eversa® Transform 2.0) on hybrid amine-epoxy core-shell magnetic nanoparticles

Magnetic nanoparticles were functionalized with polyethylenimine (PEI) and activated with epoxy. This support was used to immobilize Lipase (Eversa® Transform 2.0) (EVS), optimization using the Taguchi method. XRF, SEM, TEM, XRD, FTIR, TGA, and VSM performed the characterizations. The optimal conditions were immobilization yield (I.Y.) of 95.04 ± 0.79 %, time of 15 h, ionic load of 95 mM, protein load of 5 mg/g, and temperature of 25 °C. The maximum loading capacity was 25 mg/g, and its stability in 60 days of storage showed a negligible loss of only 9.53 % of its activity. The biocatalyst demonstrated better stability at varying temperatures than free EVS, maintaining 28 % of its activity at 70 °C. It was feasible to esterify free fatty acids (FFA) from babassu oil with the best reaction of 97.91 % and ten cycles having an efficiency above 50 %. The esterification of produced biolubricant was confirmed by NMR, and it displayed kinematic viscosity and density of 6.052 mm2/s and 0.832 g/cm3, respectively, at 40 °C. The in-silico study showed a binding affinity of -5.8 kcal/mol between EVS and oleic acid, suggesting a stable substrate-lipase combination suitable for esterification.

Study of Membrane-Immobilized Oxidoreductases in Wastewater Treatment for Micropollutants Removal

The development of efficient strategies for wastewater treatment to remove micropollutants is of the highest importance. Hence, in this study, we presented a rapid approach to the production of biocatalytic membranes based on commercially available cellulose membrane and oxidoreductase enzymes including laccase, tyrosinase, and horseradish peroxidase. Effective enzyme deposition was confirmed based on Fourier transform infrared spectra, whereas results of spectrophotometric measurements showed that immobilization yield for all proposed systems exceeded 80% followed by over 80% activity recovery, with the highest values (over 90%) noticed for the membrane-laccase system. Further, storage stability and reusability of the immobilized enzyme were improved, reaching over 75% after, respectively, 20 days of storage, and 10 repeated biocatalytic cycles. The key stage of the study concerned the use of produced membranes for the removal of hematoporphyrin, (2,4-dichlorophenoxy)acetic acid (2,4-D), 17α-ethynylestradiol, tetracycline, tert-amyl alcohol (anesthetic drug), and ketoprofen methyl ester from real wastewater sampling at various places in the wastewater treatment plant. Although produced membranes showed mixed removal rates, all of the analyzed compounds were at least partially removed from the wastewater. Obtained data clearly showed, however, that composition of the wastewater matrix, type of pollutants as well as type of enzyme strongly affect the efficiency of enzymatic treatment of wastewater.

Amylases from thermophilic bacteria: structure and function relationship

Amylases hydrolyze starch to diverse products including dextrins and progressively smaller polymers of glucose units. Thermally stable amylases account for nearly 25% of the enzyme market. This review highlights the structural attributes of the α-amylases from thermophilic bacteria. Heterologous expression of amylases in suitable hosts is discussed in detail. Further, specific value maximization approaches, such as protein engineering and immobilization of the amylases are discussed in order to improve its suitability for varied applications on a commercial scale. The review also takes into account of the immobilization of the amylases on nanomaterials to increase the stability and reusability of the enzymes. The function-based metagenomics would provide opportunities for searching amylases with novel characteristics. The review is expected to explore novel amylases for future potential applications.

Covalent immobilization of lipase from Candida rugosa on epoxy-activated cloisite 30B as a new heterofunctional carrier and its application in the synthesis of banana flavor and production of biodiesel

In this paper, an epoxy-activated cloisite (ECL) was prepared as a new heterofunctional carrier via a reaction between cloisite 30B (CL) and epichlorohydrin and utilized for covalent immobilization of lipase from Candida rugosa. The lipase immobilized on the ECL (LECL) was successfully used in the olive oil hydrolysis, synthesis of isoamyl acetate (banana flavor), and biodiesel production. The TGA, FT-IR, SEM, and XRD were used to characterize CL, ECL, and LECL. The influences of temperature, pH, thermal stability, and storage capacity were examined in the olive oil hydrolysis. The effects of solvent, temperature, time, water content, and substrates molar ratio on the yields of ester and biodiesel were also investigated. In the optimized conditions, the hydrolytic activity of LECL was 1.85 ± 0.05 U/ mg, and the maximum yield of ester and biodiesel was 91.6% and 95.4%, respectively. The LECL showed good thermal stability and storage capacity compared to the free lipase. Additionally, LECL was reusable for both esterification and transesterification after being used for nine cycles.

Extraction and reimmobilization of used commercial lipase from industrial waste

In industrial application, immobilized lipase are typically not reused and served as industrial waste after a certain process is completed. The capacity on the reusability of the spent lipase is not well studied. This current study embarks on reusing the remaining lipase from the spent immobilized enzyme. Active lipases were recovered using a simple reverse micellar extraction (RME). RME is the extraction process of targeted biomolecules using an organic solvent and a surfactant. This method was the first attempt reported on the recovery of the lipase from the used immobilized lipase. RME of the spent lipase was done using the nonionic Triton X-100 surfactant and toluene. Various parameters were optimized to maximize the lipase recovery from the used immobilized lipase. The optimum forward extraction condition was 0.075 M KCl, and backward conditions were at 0.15 M Triton X-100/toluene (pH 6, 2 M KCl) with recovery of 66%. The extracted lipase was immobilized via simple adsorption into the ethanol pretreated carrier. The optimum conditions of immobilization resulted in 96% of the extracted lipase was reimmobilized. The reimmobilized lipase was incubated for 20 h in pH 6 buffer at 50 °C of water bath shaker. The reimmobilized lipase still had 27% residual activity after 18 h of incubation, which higher thermal stability compared to the free lipase. In conclusion, the free lipase was successfully extracted from the spent immobilized lipase and reimmobilized into the new support. It exhibited high thermal stability, and the reusability of the spent lipase will promote continued use of industrial lipase and reduce the cost of the manufacturing process.

Immobilization of α-amylase on GO-magnetite nanoparticles for the production of high maltose containing syrup

Robust amylases with stability and catalysis at multitude of extremities are the need of an hour. Enzyme immobilization may prove beneficial at commercial scale to achieve such attributes. In the present study, a commercially available amylase was immobilized on graphene oxide (GO) - magnetite (Fe₃O₄) nanoparticles through covalent bonding. The structural and morphological characterizations were conducted by XRD, SEM and TEM. Further, FTIR and TGA confirmed the interaction between amylase, GO and nanoparticles. The variables, such as concentrations of GO (1.3 mg), Fe₃O₄ (58 μg), and amylase (4.5 mg) were optimized by the response surface methodology using central composite design. High loading capacity of 77.58 μg amylase over 1 μg GO-magnetite nanoparticles was achieved under optimum conditions. Biochemically, the pH optimum remained unaltered, i.e., pH 7, whereas, the alkalitolerance was increased by ~20% in relative activities upon immobilization. The half-life of soluble amylase was 13 h, which enhanced to 20 h upon immobilization in 20 mM phosphate buffer, pH 7 at 50 °C. Besides, the thermodynamic parameters supported the stability trends. The immobilized amylase could be used for 11 subsequent cycles. The mentioned attributes and the dextrose equivalent values during the production of high maltose containing syrup highlighted its commercialization.

Co-Immobilization of Glucose Dehydrogenase and Xylose Dehydrogenase as a New Approach for Simultaneous Production of Gluconic and Xylonic Acid

The conversion of biomass components catalyzed via immobilized enzymes is a promising way of obtaining valuable compounds with high efficiency under mild conditions. However, simultaneous transformation of glucose and xylose into gluconic acid and xylonic acid, respectively, is an overlooked research area. Therefore, in this work we have undertaken a study focused on the co-immobilization of glucose dehydrogenase (GDH, EC 1.1.1.118) and xylose dehydrogenase (XDH, EC 1.1.1.175) using mesoporous Santa Barbara Amorphous silica (SBA 15) for the simultaneous production of gluconic acid and xylonic acid. The effective co-immobilization of enzymes onto the surface and into the pores of the silica support was confirmed. A GDH:XDH ratio equal to 1:5 was the most suitable for the conversion of xylose and glucose, as the reaction yield reached over 90% for both monosaccharides after 45 min of the process. Upon co-immobilization, reaction yields exceeding 80% were noticed over wide pH (7–9) and temperature (40–60 °C) ranges. Additionally, the co-immobilized GDH and XDH exhibited a significant enhancement of their thermal, chemical and storage stability. Furthermore, the co-immobilized enzymes are characterized by good reusability, as they facilitated the reaction yields by over 80%, even after 5 consecutive reaction steps.

Immobilisation of α-amylase on activated amidrazone acrylic fabric: a new approach for the enhancement of enzyme stability and reusability

In this study, amidrazone acrylic fabric was applied as an immobilising support for α-amylase. The immobilised α-amylase was characterised by Fourier transform infrared spectroscopy and scanning electron microscopy. Furthermore, the optimum conditions for immobilisation efficiency, immobilisation time, reusability, kinetic parameters and pH, for the immobilisation process were examined. The study demonstrated that with 4% cyanuric chloride, and a pH of 7.0, the highest immobilization efficiency of 81% was obtained. Around 65% of the initial activity was maintained after storage at 4 °C for 8 weeks. The immobilised enzyme retained 53% of its original activity after being reused 15 times and exhibited improved stability compared with the free enzyme in relation to heavy metal ions, pH, temperature and inhibitors. The immobilised enzyme presented kinetic parameters of 2.6 mg starch and 0.65 µmol maltose/mL for K_m and V_max respectively, compared with 3.7 mg starch and 0.83 µmol maltose/ mL for the free enzyme. The improvements in the enzyme’s catalytic properties, stability and reusability obtained from immobilisation make amidrazone acrylic fabric support a good promising candidate for bio-industrial applications.

Enzyme immobilisation on poly-l-lysine-containing calcium phosphate particles for highly sensitive glucose detection

High catalytic activities of enzymes are necessary for enzyme immobilising technology for the development of glucose sensors. The aim of this study is to synthesise two types of poly(l-lysine)-containing calcium phosphate particles (pLys-HAp) and to achieve the immobilisation of glucose oxidase (GOX) on them. The oxidation activity of GOX immobilised on these particles was more than 80% compared to that of native GOX (considered to be 100%). Additionally, the relative activity of GOX immobilised on poly-ε-lysine-containing HAp (ε-pLys-HAp) remained approximately 70% after ten cycles. Moreover, glucose detection was able to be performed in the linear range of 4–400 μM using GOX immobilised on pLys-HAp composites. In the direct electrochemistry measurement using the cyclic voltammetry (CV) method, a glassy carbon electrode (GCE) modified by ε-pLys-HAp was a good enzyme electrode and can be used for glucose detection with high sensitivity. From these results, poly(l-lysine)-containing HAp composites can be expected to be enzyme immobilisation agents with high stability and biosensors with high sensitivity.

The as-synthesised poly-l-lysine-containing HAp with high enzyme stability could be a candidate for a glucose sensor with high sensitivity.

Lignin from bamboo shoot shells as an activator and novel immobilizing support for α-amylase

This study examined the feasibility of α-amylase activation and immobilization, using lignin from bamboo shoot shells (BSS). Our results demonstrated that BSS lignin is an excellent α-amylase activator and it elevated α-amylase activity more than two-fold at a concentration of 5mg/ml. For immobilization of α-amylase via adsorption, BSS lignin was incubated in an α-amylase solution (5mg/ml) for 20min, and the maximum specific activity, amount of loaded protein and activity recovery were 92.4U/mg, 19.0mg/g and 111%, respectively. In contrast to its free counterpart, immobilized α-amylase improved the catalytic efficiency and storage stability, under comparable working conditions (temperature and pH). Regarding its convenient usage, immobilized enzyme can be suspended in advance, but a suspension incubated at 60°C should be used within 30min. The residual activity after 14 re-uses remained at a reasonable level (53.2%). In conclusion, this study reveals a novel support for enzyme immobilization.

Nanomaterials as novel supports for the immobilization of amylolytic enzymes and their applications: A review

Numerous types of nanoparticles and nanocomposites have successfully been employed for the immobilization and stabilization of amylolytic enzymes; α-amylases, β-amylases, glucoamylases and pullulanases. Nano-support immobilized amylolytic enzymes retained very high activity and yield of immobilization. The immobilization of these enzymes, particularly α-amylases and pullulanases, to the nanosupports is helpful in minimizing the problem of steric hindrances during binding of substrate to the active site of the enzyme. The majority of nano-support immobilized amylolytic enzymes exhibited very high resistance to inactivation induced by different kinds of physical and chemical denaturants and these immobilized enzyme preparations maintained very high activity on their repeated and continuous uses. Amylolytic enzymes immobilized on nano-supports have successfully been applied in food, fuel, textile, paper and pulp, detergent, environmental, medical, and analytical fields.

Screening of thrombin inhibitors from phenolic acids using enzyme-immobilized magnetic beads through direct covalent binding by ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry

Thrombin was immobilized on dynabeads^®M-270 epoxy by direct covalent binding method for the first time. The enzyme coated magnetic beads were combined with ultrahigh-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry technique to establish a simple, rapid and reliable approach for screening thrombin inhibitors from Danshen preparation. The conjugation of thrombin to the magnetic beads was characterized using scanning electron microscope, transmission electron microscope and infrared spectroscopy, and the enzyme activity was determined by the analysis of enzyme-bead ratio and peak areas of target compounds. Several factors including amount of magnetic beads, type of elution solvent, incubation temperature and time were optimized. Additionally, two thrombin-bound compounds (protocatechuic aldehyde and salvianolic acid C) in Danshen injection were validated by conventional inhibitory assay and the IC₅₀ values were 286.11 and 66.09μg/mL, respectively. Our findings suggested that the proposed method was efficient in screening active compounds from medicinal plants.

Efficient Immobilization of Porcine Pancreatic α-Amylase on Amino-Functionalized Magnetite Nanoparticles: Characterization and Stability Evaluation of the Immobilized Enzyme

The potential of the modified magnetic nanoparticles for covalent immobilization of porcine pancreatic α-amylase has been investigated. The synthesis and immobilization processes were simple and fast. The co-precipitation method was used for synthesis of magnetic iron oxide (Fe₃O₄) nanoparticles (NPs) which were subsequently coated with silica through sol-gel reaction. The amino-functionalized NPs were prepared by treating silica-coated NPs with 3-aminopropyltriethoxysilane followed by covalent immobilization of α-amylase by glutaraldehyde. The optimum enzyme concentration and incubation time for immobilization reaction were 150 mg and 4 h, respectively. Upon this immobilization, the α-amylase retained more than 50 % of its initial specific activity. The optimum pH for maximal catalytic activity of the immobilized enzyme was 6.5 at 45 °C. The kinetic studies on the immobilized enzyme and its free counterpart revealed an acceptable change of K_m and V_max. The Km values were found as 4 and 2.5 mM for free and immobilized enzymes, respectively. The V_max values for the free and immobilized enzymes were calculated as 1.75 and 1.03 μmol mg^-1 min^-1, in order, when starch was used as the substrate. A quick separation of immobilized amylase from reaction mixture was achieved when a magnetically active support was applied. In comparison to the free enzyme, the immobilized enzyme was thermally stable and was reusable for 9 cycles while retaining 68 % of its initial activity.