Immobilization of soybean (Glycine max) α-amylase onto Chitosan and Amberlite MB-150 beads: Optimization and characterization

Immobilization of laccase on magnetic PEGDA-CS inverse opal hydrogel for enhancement of bisphenol A degradation in aqueous solution

Endocrine disruptors such as bisphenol A (BPA) adversely affect the environment and human health. Laccases are used for the efficient biodegradation of various persistent organic pollutants in an environmentally safe manner. However, the direct application of free laccases is generally hindered by short enzyme lifetimes, non-reusability, and the high cost of a single use. In this study, laccases were immobilized on a novel magnetic three-dimensional poly(ethylene glycol) diacrylate (PEGDA)-chitosan (CS) inverse opal hydrogel (LAC@MPEGDA@CS@IOH). The immobilized laccase showed significant improvement in the BPA degradation performance and superior storage stability compared with the free laccase. 91.1% of 100 mg/L BPA was removed by the LAC@MPEGDA@CS@IOH in 3 hr, whereas only 50.6% of BPA was removed by the same amount of the free laccase. Compared with the laccase, the outstanding BPA degradation efficiency of the LAC@MPEGDA@CS@IOH was maintained over a wider range of pH values and temperatures. Moreover, its relative activity of was maintained at 70.4% after 10 cycles, and the system performed well in actual water matrices. This efficient method for preparing immobilized laccases is simple and green, and it can be used to further develop ecofriendly biocatalysts to remove organic pollutants from wastewater.

Immobilization of α-amylase onto functionalized molybdenum diselenide nanoflowers (MoSe2-NFs) as scaffolds: Characterization, kinetics, and potential applications in starch-based industries

The current study presents the application of molybdenum diselenide nanoflowers (MoSe2-NFs) as an innovative substrate for immobilizing α-amylase by glutaraldehyde activation. This approach results in the development of a nanobiocatalyst that exhibits remarkable advantages compared to a standalone enzyme. Several physical methods, such as fluorescence microscopy, FT-IR, SEM, TEM, XRD, AFM, and Raman spectroscopy, were used to confirm that α-amylase was successfully attached to MoSe2-NFs. By employing the Box-Behnken design of the RSM, the parameters were optimized, resulting in an immobilization efficiency of roughly 87.33%. The immobilized variant of α-amylase demonstrated superior thermostability, pH stability, reusability, and storage stability in comparison to the soluble enzyme. The catalytic activity of α-amylase was highest when immobilized on MoSe2-NFs at the same pH and temperature as the soluble enzyme. However, there was an expansion in the range of parameters in which this activity was observed. Furthermore, the immobilized enzyme exhibited a retention of nearly 80% residual activity following 12 successive reuses. The immobilized enzyme exhibited around 82% residual activity after being stored for 120 days. It is possible that the immobilization process changed the Michaelis-Menten constant, which means that the substrate could no longer reach certain active sites on the enzyme because it had become longer. The study's findings suggest that the α-amylase-MoSe2-NFs system could be useful in industry because it can work in a wider range of temperature and pH conditions. Furthermore, the intrinsic non-toxic characteristics of the matrix, along with its ability to be kept for prolonged periods and recycled, render nano biocatalysts very well-suited for the effective synthesis of maltose in the food and pharmaceutical industries.

Pros and Cons in Various Immobilization Techniques and Carriers for Enzymes

In recent years, enzyme immobilization technology has been developed, and studies on immobilized enzyme materials have become very prominent. With the immobilization technique, enzymes and compatible carrier materials are combined or enzyme crystals/aggregates are used in a carrier-free fashion, by physical, chemical, or biochemical methods. As a kind of biocatalyst, immobilized enzymes can catalyze certain chemical reactions with high selectivity and high efficiency under relatively mild reaction conditions and eliminate pollution to the environment. Considering the current status and applications of immobilized enzyme technology and materials emerging in the last 5 years, this mini-review introduces the advantages and disadvantages of various enzyme immobilization techniques with carriers as well as the pros and cons of different materials for immobilization. The future prospects of immobilization technology and carrier materials are outlined, aiming to provide a reference for further research and applications of sustainable technology.

Comparison of Immobilized and Free Amyloglucosidase Process in Glucose SyrupsProduction from White Sorghum Starch

Optimum conditions for glucose syrups production from white sorghum were studied through sequential liquefaction and saccharification processes. In the liquefaction process, a maximum dextrose equivalent (DE) of 10.98 % was achieved using 30 % (w/v) of starch and Termamyl ɑ-amylase from Bacillus licheniformis. Saccharification was performed by free and immobilized amyloglucosidase from Rhizopus mold at 1 % (w/v). DE values of 88.32 % and 79.95 % were obtained from 30 % (w/v) of starch with, respectively, free and immobilized enzyme. The immobilized Amyloglucosidase in calcium alginate beads showed reusable capacity for up to 6 cycles with 46 % of the original activity retained. The kinetic behaviour of immobilized and free enzyme gives Km value of 22.13 and 16.55 mg mL-1 and Vmax of 0.69 and 1.61 mg mL-1  min-1 , respectively. The hydrolysis yield using immobilized amyloglucosidase were lower than that of the free one. However, it is relevant to reuse enzyme without losing activity in order to trim down the overall costs of enzymatic bioprocesses as starch transformation into required products in industrial manufacturing. Hydrolysis of sorghum starch using immobilized amyloglucosidase represents a promising alternative towards the development of the glucose syrups production process and its utilization in various industries.

Immobilization of Urease onto Nanochitosan Enhanced the Enzyme Efficiency: Biophysical Studies and in Vitro Clinical Application on Nephropathy Diabetic Iraqi Patients

Immobilization of enzymes is an effective method for improving the properties and applications of modern enzymes. There are several supports for enzyme immobilization. Because of its unique features, such as inertness and high surface area, chitosan was widely used to immobilize enzymes. Immobilization of urease onto chitosan is a promising approach to treating high urea levels in the blood, however, the immobilization conditions for the best kinetics and enzyme efficiency are still challenging. Herein, we tried to immobilize urease onto nanochitosan (chitosan NPs) through a cross-linker and study the kinetics (km and $v_{\max }$ values) and thermodynamics (Ea, ∆H, ∆S, and ∆G) parameters of the enzyme reaction before and after immobilization at different substrate concentration (50, 100, 150, 200, and 250 mg/dl) and incubation temperature (15, 20, 25, 30, 35, and 40°C) under selected optimum conditions. The immobilized urease chitosan NPs was characterized in our previous work using Fourier transform infrared $\text{infrared}$ (FTIR), Atomic force $\text{force}$ microscopy (AFM), and $\text{and}$ imaged here by scanning electron microscopy $\text{microscopy}$ (SEM). Results revealed that the highest efficiency % of immobilization (70.38%) was observed at 750 mg/ml chitosan NPs and phosphate buffer pH 7 at 40°C. With an increase of Km value for the immobilized enzyme, however, the efficiency of the enzyme was significantly higher than the free enzyme, $p<0.001$ . In addition, the activation energy of the reaction catalyzed by the immobilized enzyme was lower than that of the free enzyme, which suggests that the active site geometry of the immobilized enzyme was more favorable to accommodate the substrate and thus required less energy than that of the free enzyme. The reaction was endothermic by means of positive ∆H. The immobilized urease enzyme was in vitro applied to blood samples of Iraq nephropathy diabetic patients (n = 35) to investigate the effect on serum urease activity and urea level compared to healthy volunteers. Interestingly, the activity of serum urease significantly increased after adding the immobilized enzyme and the level of urea significantly decreased ( $p<0.0001$ ) by ∼1.5 folds. Thus, applying an immobilized urease $\text{urease}$ to remove urea from blood could be effective in the blood detoxification or dialysis regeneration system of artificial kidney machines.

The Stability Improvement of Aspergillus fumigatus α-Amylase by Immobilization onto Chitin-Bentonite Hybrid

Enzyme immobilization is a powerful method to improve the stability, reuse, and enzymatic properties of enzymes. The immobilization of the α-amylase enzyme from Aspergillus fumigatus on a chitin-bentonite (CB) hybrid has been studied to improve its stability. Therefore, this study aims to obtain the higher stability of α-amylase enzyme to reduce industrial costs. The procedures were performed as follows: production, isolation, partial purification, immobilization, and characterization of the free and immobilized enzymes. The CB hybrid was synthesized by bentonite, chitin, and glutaraldehyde as a cross-linker. The free enzyme was immobilized onto CB hybrid using 0.1 M phosphate buffer pH 7.5. The free and immobilized enzymes were characterized by optimum temperature, Michaelis constant (K_M), maximum velocity (V_max), thermal inactivation rate constant (k_i), half-life (t_1/2), and transformation of free energy because of denaturation (ΔG_i). The free enzyme has optimum temperature of 55°C, K_M = 3.04 mg mL⁻¹ substrate, V_max=10.90 μmolemL⁻¹min⁻¹, k_i = 0.0171 min⁻¹, t_1/2 = 40.53 min, and ΔG_i = 104.47 kJ mole⁻¹. Meanwhile, the immobilized enzyme has optimum temperature of 60°C, K_M = 11.57 mg mL⁻¹ substrate, V_max=3.37 μmolemL⁻¹min⁻¹, k_i = 0.0045 min⁻¹, t_1/2 = 154.00 min, and ΔG_i = 108.17 kJ mole⁻¹. After sixth cycle of reuse, the residual activity of the immobilized enzyme was 38%. The improvement in the stability of α-amylase immobilized on the CB hybrid based on the increase in half-life was four times of the free enzyme.

Immobilization of Trametes versicolor laccase on chitosan/halloysite as a biocatalyst in the Remazol Red RR dye

In this study, the laccase obtained from Trametes versicolor was immobilized onto the chitosan(CTS)/halloysite (HNT) beads. In the immobilization step, the effects of chitosan (1-3% w/v), halloysite (0-2% w/v), glutaraldehyde (0.5-1.5% v/v) and enzyme concentrations (1-3%) on loading and immobilization efficiency were investigated. SEM, FT-IR, XRD, TGA and XPS analyses were performed to examine the structure of beads. In addition, the effects of parameters such as pH (4-10), temperature (25-55 °C), storage life on the activity of free and immobilized laccase were also investigated. The activities of free and immobilized laccase preserved 23% and 56% of its initial activity at the end of 59 days of storage. The effects of mediators such as 2.2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS), 1-Hydroxybenzotriazole hydrate (HBT), 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO) and violuric acid (VLA) on the dye removal efficiency were investigated. Reusability of the CTS/HNT/Lac in the presence of HBT and VLA mediators, which enable the highest dye removal, was tested. After 15 cycles, 42% and 54% dye removal were achieved with the CTS/HNT/Lac in the medium containing HBT and VLA, and 42% and 49% of the activity is preserved, respectively. This study showed that CTS/HNT/Lac can be used repeatedly for Remazol Red RR dye removal.

Immobilization of the Tannase From Aspergillus fumigatus CAS21: Screening the Best Derivative for the Treatment of Tannery Effluent Using a Packed Bed Reactor

Enzyme immobilization is an important alternative to stabilize enzyme properties favoring the efficiency of derivatives (enzyme + support/matrix) for different purposes. According to this, the current study aimed to immobilize the Aspergillus fumigatus CAS21 tannase and the use of the derivatives in the treatment of the effluent produced by the tannery industry. The tannase was immobilized on sodium alginate, DEAE-Sephadex, amberlite, and glass pearls as supports. Calcium alginate was the most adequate support for tannase immobilization with 100% yield and 94.3% for both efficiency and activity. The best tannase activity for the calcium alginate derivative was obtained at 50°C–60°C and pH 5.0. Thermal and pH stabilities evaluated for 24 h at 30°C–60°C and pH 4–7, respectively, were improved if compared to the stability of the free enzyme. Considering the reuse of the calcium alginate derivative, 78% of the initial activity was preserved after 10 catalytic cycles, and after the 9-month storage at 4°C, the activity was maintained in 70%. This derivative was applied in a packed bed reactor (PBR) for the treatment of tannin-rich effluents from the tannery industry. The reduction of the tannin content was effective reaching degradation of 74–78% after 48 h of PBR operation. The concentration of total phenolic compounds was also reduced, and the color and clarity of the effluent improved. In conclusion, the calcium alginate derivative is an attractive alternative as biocatalyst for large-scale treatment of the effluents from the tannery industry.

Cibacron blue F3GA incorporated immobilized metal chelate affinity sorbent as a high efficient affinity immobilization materials for catalase enzyme

Catalase is a metalloenzyme commonly found in almost all plant and animal tissues and catalyzes the conversion of hydrogen peroxide to less reactive molecules. It is used for the elimination of hydrogen peroxide in biological, biomedical, food and textile applications. For this purpose, a novel affinity sorbent [poly(methacrylic acid- N-isopropyl acrylamide-CB-Fe³⁺, (p(MAA-NIPAAM)-CB-Fe³⁺)] for the determination and it was first developed using MAA and NIPAAM monomers. After characterization with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), X-ray Photoelectron Spectroscopy (XPS), adsorption parameters were determined. Reusability of p(MAA-NIPAAM)-CB-Fe³⁺ sorbent was determined after by determining the appropriate desorption agent for desorption of adsorbed catalase in the developed sorbent. It was determined that catalase adsorption could be performed with 0.01 g of sorbent in 45 min. The maximum adsorption capacity for catalase adsorption was determined as 243.17 mg/g with the use of sorbent. The operational and storage stability of the immobilized catalase was found to be high as expected. The conversion of H₂O₂ can be successfully performed by the immobilized enzyme in the prepared sorbent. It has been proven that the affinity of catalase for its substrate is increased by immobilization.

Nano-organic supports for enzyme immobilization: Scopes and perspectives

A variety of organic nanomaterials and organic polymers are used for enzyme immobilization to increase enzymes stability and reusability. In this study, the effects of the immobilization of enzymes on organic and organic-inorganic hybrid nano-supports are compared. Immobilization of enzymes on organic support nanomaterials was reported to significantly improve thermal, pH and storage stability, acting also as a protection against metal ions inhibitory effects. In particular, the effects of enzyme immobilization on reusability, physical, kinetic and thermodynamic parameters were considered. Due to their biocompatibility with low health risks, organic support nanomaterials represent a good choice for the immobilization of enzymes. Organic nanomaterials, and especially organic-inorganic hybrids, can significantly improve the kinetic and thermodynamic parameters of immobilized enzymes compared to macroscopic supports. Moreover, organic nanomaterials are more environment friendly for medical applications, such as prodrug carriers and biosensors. Overall, organic hybrid nanomaterials are receiving increasing attention as novel nano-supports for enzyme immobilization and will be used extensively.

MPH-GST sensing microplate for easy detection of organophosphate insecticides

OBJECTIVE

To develop a convenient and efficient means for organophosphate (OP) insecticide detection, a simple, cost-effective, and easy-to-use absorbance-based sensing device was generated using methyl parathion hydrolase fused with glutathione-S-transferase (MPH-GST) covalently immobilized onto a chitosan film-coated microplate.

RESULTS

With methyl parathion (MP) as a representative substrate, this MPH-GST sensing microplate had the detection limit of 0.1 µM and the linear range of 0.1-50 µM. Despite its highest stability at 4 °C, it was considerably stable at 25 °C with high activity for 30 days. It was also most stable at pH 8.0 and could be efficiently reused up to 100 rounds. The device revealed a high percentage of recovery for tap water spiked with a known concentration of MP, which was also comparable to the result obtained from gas chromatography-mass spectrometry. It also showed a high recovery of 82-100% with MP spiked agricultural products and satisfactory results with non-spiked samples. This immobilized enzyme sensing system was more sensitive and efficient than the whole cell system from our previous work.

CONCLUSIONS

All of the advantages of the MPH-GST sensing microplate developed have rendered it suitable for rapid and convenient OP screening, and for being a bio-element for fabricating a potential optical biosensor in the future.

Hydroxyapatite-decorated ZrO2 for α-amylase immobilization: Toward the enhancement of enzyme stability and reusability

Herein, the immobilization of α-amylase onto hydroxyapatite (HA) and hydroxyapatite-decorated ZrO₂ (10%wt) (HA-ZrO₂) nanocomposite were investigated. The immobilization yield was 69.7% and 84% respectively. The structural differences were characterized using X-Ray diffraction, attenuated total reflectance-Fourier transform infrared spectra, Raman, and scanning electron microscope. After 10 repeated cycles, the residual activity of immobilized α-amylase onto HA and HA-ZrO₂ nanocomposite was 46% and 70%, respectively. The storage stability was recorded to be 27%, 50% and 69% from its initial activity in the case of free and immobilized enzyme onto HA and HA-ZrO₂ nanocomposite, respectively after 8 weeks. The pH-activity profile and temperature revealed pH 6.0 and temperature 50 °C as the optimal values of free α-amylase, while the optimum values for α-amylase on HA and HA-ZrO₂ was shifted to pH 6.5 and 60 °C after immobilization. The immobilized α-amylase onto HA-ZrO₂ showed comparatively higher catalytic activity than the free α-amylase. The Km value after the immobilization process onto HA was 2.1 folds highly than that of the free enzyme. In conclusion, it can be inferred that HA-ZrO₂ is more sustainable and beneficial support for enzyme immobilization and it represents promising supports for different uses of α-amylase in the biomedical applications.

Heterologous expression, purification, immobilization and characterization of recombinant α-amylase AmyLa from Laceyella sp. DS3

AmyLa α-amylase gene from Laceyella sp. DS3 was heterologously expressed in E. coli BL21. E. coli BL21 maximally expressed AmyLa after 4 h of adding 0.02 mM IPTG at 37 °C. The recombinant AmyLa α-amylase was purified 2.19-fold through gel filtration and ion exchange chromatography. We immobilized the purified recombinant AmyLa α-amylase on four carriers; chitosan had the best efficiency. The recombinant free and the immobilized AmyLa α-amylase showed optimum activity in the pH ranges of 6.0-7.0 and 4.0-7.0, respectively and possessed an optimum temperature of 55 °C. The free enzyme had activation energy, Km, and Vmax of 291.5 kJ, 1.5 mg/ml, and 6.06 mg/min, respectively. The immobilized enzyme had activation energy, Km, and Vmax of 309.74 kJ, 6.67 mg/ml, and 50 mg/min, respectively. The immobilized enzyme was calcium-independent and insensitive (relative to the free enzyme) to metals. It could also be reused for seven cycles.

Evolutionary Trends in Industrial Production of α-amylase

BACKGROUND

Amylase catalyzes the breakdown of long-chain carbohydrates to yield maltotriose, maltose, glucose and dextrin as end products. It is present in mammalian saliva and helps in digestion.

OBJECTIVE

Their applications in biotechnology include starch processing, biofuel, food, paper, textile and detergent industries, bioremediation of environmental pollutants and in clinical and medical applications. The commercial microbial strains for production of α-amylase are Bacillus subtilis, B. licheniformis, B. amyloliquefaciens and Aspergillus oryzae. Industrial production of enzymes requires high productivity and cannot use wild-type strains for enzyme production. The yield of enzyme from bacteria can be increased by varying the physiological and genetic properties of strains.

RESULTS

The genetic properties of a bacterium can be improved by enhancing the expression levels of the gene and secretion of the enzyme outside the cells, thereby improving the productivity by preventing degradation of enzymes. Overall, the strain for specific productivity should have the maximum ability for synthesis and secretion of an enzyme of interest. Genetic manipulation of α-amylase can also be used for the production of enzymes with different properties, for example, by recombinant DNA technology.

CONCLUSION

This review summarizes different techniques in the production of recombinant α- amylases along with the patents in this arena. The washing out of enzymes in reactions became a limitation in utilization of these enzymes in industries and hence immobilization of these enzymes becomes important. This paper also discusses the immobilization techniques for used α-amylases.

Preparation of chitosan-based nanoparticles for enzyme immobilization

The aim of the present work was to prepare high loading capacity carriers for immobilizing glucoamylase. Different sizes of chitosan based particles were successfully prepared by different methods to evaluate the performance in immobilization. Chitosan particles on millimeter size were prepared by dripping granulation method, chitosan covered magnetic nanoparticles and chitosan mixted graphene oxide nanosheets covered magnetic nanoparticles were synthesized by one-step method, chitosan-glucoamylase nanoparticles were synthesized by ionic cross linking method with Sodium tripolyphosphate. These particles were characterized by SEM, TEM, FTIR and DLS analysis. The performance of the immobilized enzyme was also investigated. The results showed that the loading capacity was greatly increased on chitosan based nanoparticles. The reaction conditions of immobilized enzyme were optimized, the reusability and storage stability was also investigated. The results showed the pH durance and storage stability of the immobilized enzyme on nanosize particles were enhanced.

Random mutagenesis of super Koji (Aspergillus oryzae): improvement in production and thermal stability of α-amylases for maltose syrup production

Background

Alpha-amylases hydrolyze 1,4 α-glycosidic bonds of starch and produce malto-oligosaccharides. It is an important enzyme generally applied in textile, food and brewing industries. Enhancement in thermal stability and productivity of enzymes are the two most sought after properties for industrial use. The Aspergillus oryzae (Koji) has Generally Recognized as Safe (GRAS) status and safe for use in food industry. Hence, Koji strain’s development for the screening of potent mutants, hyper producer of thermostable α-amylases, with desired attributes is the need of the time.

Results

A process has been developed to improve super Koji (A. oryzae cmc1) strain through γ-rays treatment. The doses i.e. 0.60, 0.80, 1.00, 1.20 & 1.40 KGy gave more than 3.0 log kill. Initially, 52 Koji mutants resistant to 1% (w/v) Triton X-100 were selected. 2^nd screening was based on α-amylases hyper production and 23 mutants were sorted out by measuring clearing zones index (CI). Afterwards nine potent mutants, resistant to 2-deoxy D-glucose, were screened based on CI. These were further analyzed for thermal stability and productivity of α-amylase under submerged conditions. The mutants’ M-80(10), M-100(6) & M-120(5) gave about four fold increases in α-amylases productivity. The half life of M-100(6) α-amylase at 55 °C was 52 min and was highest among the mutants. Liquid Chromatography-Mass Spectrometry (LC-MS) analysis confirmed that mutants did not produce aflatoxins. Field Emission Scanning Electron Microscopy (FESEM) of Koji mycelia depicted that exposure to gamma rays increased rigidity of the mycelium. The potent Koji mutant M-100(6) was grown on soluble starch in 10L fermenter and produced 40.0 IU ml^-1 of α-amylases with specific activity of 2461 IU mg^-1 protein. Growth kinetic parameters were: μ = Specific growth rate= 0.069 h^-1, t_d = Biomass doubling time= 10.0 h, Y_p/x = Product yield coefficient with respect to cell mass = 482 U g^-1; q_p= Specific rate of product formation= 33.29 U g^-1 h^-1.

Conclusion

It was concluded that the developed five step screening process has great potential to generate potent mutants for the hyper production of thermostable enzymes through γ-rays mediated physical mutagenesis. The developed thermostable α-amylases of super Koji mutantM-100(6) has immense potential for application in saccharification process for maltose syrup production. Moreover, the developed five step strain’s development process may be used for the simultaneous improvement in productivity and thermal stability of other microbial enzymes.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1345-y) contains supplementary material, which is available to authorized users.

Immobilization of catalase onto chitosan and chitosan-bentonite complex: A comparative study

•

Characteristics of free and immobilized catalase.

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The kinetic parameters and stability of free and immobilized catalase were studied.

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FTIR spectra of free and immobilized catalase were studied.

The immobilization of catalase onto chitosan and chitosan–bentonite was investigated and immobilization yield of 95.91 and 95.26 was obtained respectively. The optimum pH and temperature were found as 7.5 and 8.0 at 40 °C for free and immobilized enzyme. The value of V_max decreased by 33,000–26,300, 24,500 μmol (min mg protein)⁻¹ and K_m increased by 12.5–25 and 20 mM for free and immobilized on chitosan and chitosan–bentonite respectively. The thermal stability, half life, FTIR analyses of the beads was also performed in order to characterise the structural differences. The remaining immobilized catalase onto chitosan and chitosan–bentonite activity was 50% and 70% after 20 cycles respectively. The storage stability were found as 22%, 60%, and 70% from its original activity in case of free enzyme and immobilization of chitosan, chitosan–bentonite beads respectively after 60 days.

Optimization, Purification, and Starch Stain Wash Application of Two New α-Amylases Extracted from Leaves and Stems of Pergularia tomentosa

A continuous research is attempted to fulfil the highest industrial demands of natural amylases presenting special properties. New α-amylases extracted from stems and leaves of Pergularia tomentosa, which is widespread and growing spontaneously in Tunisia, were studied by the means of their activities optimization and purification. Some similarities were recorded for the two identified enzymes: (i) the highest amylase activity showed a promoted thermal stability at 50°C; (ii) the starch substrate at 1% enhanced the enzyme activity; (iii) the two α-amylases seem to be calcium-independent; (iv) Zn2+, Cu2+, and Ag2+ were considered as important inhibitors of the enzyme activity. Following the increased gradient of elution on Mono Q-Sepharose column, an increase in the specific activity of 11.82-fold and 10.92-fold was recorded, respectively, for leaves and stems with the presence of different peaks on the purification profiles. Pergularia amylases activities were stable and compatible with the tested commercial detergents. The combination of plant amylase and detergent allowed us to enhance the wash performance with an increase of 35.24 and 42.56%, respectively, for stems and leaves amylases. Characterized amylases were reported to have a promoted potential for their implication notably in detergent industry as well as biotechnological sector.

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

Stability of enzymes is an important parameter for their industrial applicability. Here, we report successful immobilization of β-amylase (bamyl) from peanut (Arachis hypogaea) onto Graphene oxide-carbon nanotube composite (GO-CNT), Graphene oxide nanosheets (GO) and Iron oxide nanoparticles (Fe₃O₄). The Box-Behnken Design of Response Surface Methodology (RSM) was used which optimized parameters affecting immobilization and gave 90%, 88% and 71% immobilization efficiency, respectively, for the above matrices. β-Amylase immobilization onto GO-CNT (bamyl@GO-CNT) and Fe₃O₄ (bamyl@Fe₃O₄), resulted into approximately 70% retention of activity at 65 °C after 100 min of exposure. We used atomic force microscopy (AFM), scanning and transmission electron microscopy (SEM and TEM), Fourier transformed infrared (FT-IR) spectroscopy and fluorescence microscopy for characterization of free and enzyme bound nanostructures (NS). Due to the non-toxic nature of immobilization matrices and simple but elegant immobilization procedure, these may have potential utility as industrial biocatalysts for production of maltose.

Enhanced bio-catalytic performance and dye degradation potential of chitosan-encapsulated horseradish peroxidase in a packed bed reactor system

In this study, horseradish peroxidase (HRP) was immobilized onto chitosan beads by entrapment method and employed for the degradation of textile dyes. Stable and firm quality chitosan beads developed with 2.5% chitosan concentration exhibited maximum immobilization yield (~92.54±2.53%). The pH optimum of chitosan-immobilized HRP (CTS-HRP) was marginally displaced towards alkaline region (pH7.5) than that of F-HRP which displayed its optimum activity at pH7.0. The free HRP (F-HRP) and CTS-HRP enzyme presented their maximum catalytic activities at 30°C and 70°C, respectively. Relative activities of F-HRP and CTS-HRP were decreased following pre-incubation above 30°C and 50°C, respectively and after 120min at 70°C, the F-HRP, and CTS-HRP retained 19.3±1.3 and 48.3±2.4% activities, accordingly. The CTS-HRP exhibited remarkably better resistance towards heavy metal induced activity inhibition. The effect of potential inhibitors on the activity of F-HRP and CTS-HRP was investigated and found that CTS-HRP was significantly less vulnerable to the denaturation caused by urea, ethylenediaminetetraacetic acid (EDTA), cysteine, 1, 4-dithiothreitol and Triton X-100. Moreover, the CTS-assisted entrapped-HRP was also employed for the decolorization of four different textile dyes i.e. Remazol Brilliant Blue R (RBBR), Reactive Black 5 (RB5), Congo Red (CR) and Crystal Violet (CV). The CTS-HRP showed considerable decolorization efficacy in six consecutive batch operations. Results suggest that CTS-HRP is an attractive choice for use as industrial biocatalyst in larger scale bioremediation of textile dyes and effluents.

Bioinspired Multifunctional Membrane for Aquatic Micropollutants Removal

Micropollutants present in water have many detrimental effects on the ecosystem. Membrane technology plays an important role in the removal of micropollutants, but there remain significant challenges such as concentration polarization, membrane fouling, and variable permeate quality. The work reported here uses a multifunctional membrane with rejection, adsorption, and catalysis functions to solve these problems. On the basis of mussel-inspired chemistry and biological membrane properties, a multifunctional membrane was prepared by applying "reverse filtration" of a laccase solution and subsequent "dopamine coating" on a nanofiltration (NF) membrane support, which was tested on bisphenol A (BPA) removal. Three NF membranes were chosen for the preparation of the multifunctional membranes on the basis of the membrane properties and enzyme immobilization efficiency. Compared with the pristine membrane, the multifunctional membrane exhibited significant improvement of BPA removal (78.21 ± 1.95%, 84.27 ± 7.30%, and 97.04 ± 0.33% for NT103, NF270, and NF90, respectively), all of which are clearly superior to the conventional Fenton treatment (55.0%) under similar conditions and comparable to soluble laccase coupled with NF270 membrane filtration (89.0%). The improvement would appear to be due to a combination of separation (reducing the enzymatic burden), adsorption (enriching the substrate concentration as well as prolonging the residence time), and lastly, catalysis (oxidizing the pollutants and breaking the "adsorption saturation limits"). Furthermore, the synergistic effect of the polydopamine (PDA) layer on the enzymatic oxidation of BPA was confirmed, which was due to its enhanced adsorption and electron transfer performance. The multifunctional membrane could be reused for at least seven cycles with an acceptable activity loss, demonstrating good potential for removal of micropollutants.

Enzyme Immobilization: An Overview on Methods, Support Material, and Applications of Immobilized Enzymes

Immobilized enzymes can be used in a wide range of processes. In recent years, a variety of new approaches have emerged for the immobilization of enzymes that have greater efficiency and wider usage. During the course of the last two decades, this area has rapidly expanded into a multidisciplinary field. This current study is a comprehensive review of a variety of literature produced on the different enzymes that have been immobilized on various supporting materials. These immobilized enzymes have a wide range of applications. These include applications in the sugar, fish, and wine industries, where they are used for removing organic compounds from waste water. This study also reviews their use in sophisticated biosensors for metabolite control and in situ measurements of environmental pollutants. Immobilized enzymes also find significant application in drug metabolism, biodiesel and antibiotic production, bioremediation, and the food industry. The widespread usage of immobilized enzymes is largely due to the fact that they are cheaper, environment friendly, and much easier to use when compared to equivalent technologies.

Immobilization of Glycoside Hydrolase Families GH1, GH13, and GH70: State of the Art and Perspectives

Glycoside hydrolases (GH) are enzymes capable to hydrolyze the glycosidic bond between two carbohydrates or even between a carbohydrate and a non-carbohydrate moiety. Because of the increasing interest for industrial applications of these enzymes, the immobilization of GH has become an important development in order to improve its activity, stability, as well as the possibility of its reuse in batch reactions and in continuous processes. In this review, we focus on the broad aspects of immobilization of enzymes from the specific GH families. A brief introduction on methods of enzyme immobilization is presented, discussing some advantages and drawbacks of this technology. We then review the state of the art of enzyme immobilization of families GH1, GH13, and GH70, with special attention on the enzymes β-glucosidase, α-amylase, cyclodextrin glycosyltransferase, and dextransucrase. In each case, the immobilization protocols are evaluated considering their positive and negative aspects. Finally, the perspectives on new immobilization methods are briefly presented.

Laccase immobilized on PAN/O-MMT composite nanofibers support for substrate bioremediation: a de novo adsorption and biocatalytic synergy

The engineering of supports for enzyme immobilization while retaining competent functionality is nontrivial.