Immobilization ofCryptococcus flavusα-amylase on glass tubes and its application in starch hydrolysis

Application of Hierarchically Porous Chitosan Monolith for Enzyme Immobilization

Enzyme immobilization is a crucial technique for improving the stability of enzymes. Compared with free enzymes, immobilized enzymes offer several advantages in industrial applications. Efficient enzyme immobilization requires a technique that integrates the advantages of physical absorption and covalent binding while addressing the limitations of conventional support materials. This study offers a practical approach for immobilizing α-amylase on a hierarchically porous chitosan (CS) monolith. An optimized CS monolith was fabricated using chemically modified chitin by thermally induced phase separation. By combining physical adsorption and covalent bonding, this technique leverages the amino and hydroxy groups present in CS to facilitate effective enzyme binding and stability. α-Amylase immobilized on the CS monolith demonstrated excellent stability, reusability, and increased activity compared to its soluble counterpart across various pH levels and temperatures. In addition, the CS monolith exhibited a significant potential to immobilize other enzymes, namely, lipase and catalase. Immobilized lipase and catalase exhibited higher loading capacities and enhanced activities than their soluble forms. This versatility highlights the broad applicability of CS monoliths as support materials for various enzymatic processes. This study provides guidelines for fabricating hierarchical porous monolith structures that can provide efficient enzyme utilization in flow systems and potentially enhance the cost-effectiveness of enzymes in industrial applications.

An Accessible Method to Improve the Stability and Reusability of Porcine Pancreatic α-Amylase via Immobilization in Gellan-Based Hydrogel Particles Obtained by Ionic Cross-Linking with Mg2+ Ions

Amylase is an enzyme used to hydrolyze starch in order to obtain different products that are mainly used in the food industry. The results reported in this article refer to the immobilization of α-amylase in gellan hydrogel particles ionically cross-linked with Mg2+ ions. The obtained hydrogel particles were characterized physicochemically and morphologically. Their enzymatic activity was tested using starch as a substrate in several hydrolytic cycles. The results showed that the properties of the particles are influenced by the degree of cross-linking and the amount of immobilized α-amylase enzyme. The temperature and pH at which the immobilized enzyme activity is maximum were T = 60 °C and pH = 5.6. The enzymatic activity and affinity of the enzyme to the substrate depend on the particle type, and this decreases for particles with a higher cross-linking degree owing to the slow diffusion of the enzyme molecules inside the polymer's network. By immobilization, α-amylase is protected from environmental factors, and the obtained particles can be quickly recovered from the hydrolysis medium, thus being able to be reused in repeated hydrolytic cycles (at least 11 cycles) without a substantial decrease in enzymatic activity. Moreover, α-amylase immobilized in gellan particles can be reactivated via treatment with a more acidic medium.

Maltooligosaccharides: Properties, Production and Applications

Maltooligosaccharides (MOS) are homooligosaccharides that consist of 3-10 glucose molecules linked by α-1,4 glycosidic bonds. As they have physiological functions, they are commonly used as ingredients in nutritional products and functional foods. Many researchers have investigated the potential applications of MOS and their derivatives in the pharmaceutical industry. In this review, we summarized the properties and methods of fabricating MOS and their derivatives, including sulfated and non-sulfated alkylMOS. For preparing MOS, different enzymatic strategies have been proposed by various researchers, using α-amylases, maltooligosaccharide-forming amylases, or glycosyltransferases as effective biocatalysts. Many researchers have focused on using immobilized biocatalysts and downstream processes for MOS production. This review also provides an overview of the current challenges and future trends of MOS production.

Biochemical Study of Bacillus stearothermophilus Immobilized Lipase for Oily Wastewater Treatment

Traditional wastewater treatments involve expensive mechanical and physiochemical methods, so researchers have been developing cost-effective, sustainable technologies that use enzymes to produce higher quality effluents and recover more energy and nutrients from wastewater. A thermostable, alkaline, and solvent-tolerant lipase was partially purified from thermophilic Bacillus stearothermophilus. The lipase displayed maximum activity at 50 °C and pH 11.0 and catalyzed both short- and long-chain triacylglycerols at similar rates. B. stearothermophilus lipase also exhibited high stability when incubated at 40 °C for 1 h with anionic and non-ionic surfactants. Studies show that thermostable enzymes can be improved through immobilization and modification of other reaction conditions. Therefore, B. stearothermophilus lipase was immobilized through adsorption on CaCO3, Celite 545, and silica gel with the CaCO3 support producing the best adsorption rate (89.33%). The optimal initial lipase activity was approximately 4500 U.g−1 after 60 min. Interestingly, 93% of the initial lipase activity was retained after six cycles, and almost 50% of the initial activity remained after 12 cycles. Furthermore, immobilization improved storage stability with 98.85% of the initial lipase activity retained after 60 days of storage at 4 °C. The biochemical characteristics of immobilized lipase shifted toward a slightly alkaline region, reaching maximum activity at pH 12. The optimal temperature of immobilized lipase was 60 °C. Immobilization also improved enzymatic stability by widening the pH range from 5–9 (for free lipase) to 4–11, and thermostability by reaching 65 °C. The application of immobilized lipase in wastewater treatment was observed through oil layer biodegradation. Notably, treating wastewater for 10 days with immobilized lipase almost removed the chemical oxygen demand (COD) from 1950.1 down to 4.04 mg.L−1. Similarly, lipid content was almost removed from 15,500 ± 546 mg.L−1 down to 12 mg.L−1. All results highlight the potential value of CaCO3-immobilized lipase as an effective biocatalyst for hydrolyzing wastewater.

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 enzyme on a protein @metal-organic framework nanocomposite: A new strategy to develop the reusability and stability of the enzyme

Metal-organic structures (MOFs) have been designed for a wide range of applications due to their high porosity, large surface area, and flexibility. For the first time in this work, the successful immobilization of α-amylase is confirmed by the use of ZIF-8 as easy and good support. The morphology, functional groups, and chemical composition of the support and immobilized α-amylase were tested using different methods such as scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravimetric analysis (TGA). The enzymatic activities of the immobilized olibanum-bovine serum albumin@zeolitic imidazolate frameworks nanocomposite (OLB/BSA@ZIF-8)-α-amylase were compared with the free one. The pH and thermal stability of the OLB/BSA@ZIF-8-α-amylase were significantly enhanced compared to the free enzyme. The OLB/BSA@ZIF-8-α-amylase displayed excellent long-term storage stability, which could protect more than 90% of the initial activity for 8 weeks. Besides, the OLB/BSA@ZIF-8-α-amylase had high reusability, which showed a high degree of activity (more than 81%) after 20 cycles. This is the first study that uses OLB/BSA@ZIF-8 nanocomposite as immobilizing support for the immobilization of α-amylase. Improved catalytic efficiency (V_max/K_m) values, reusability, and storage stability of immobilized α-amylase can make it suitable in industrial and biotechnological applications.

The Immobilization of Lipases on Porous Support by Adsorption and Hydrophobic Interaction Method

Four major enzymes commonly used in the market are lipases, proteases, amylases, and cellulases. For instance, in both academic and industrial levels, microbial lipases have been well studied for industrial and biotechnological applications compared to others. Immobilization is done to minimize the cost. The improvement of enzyme properties enables the reusability of enzymes and facilitates enzymes used in a continuous process. Immobilized enzymes are enzymes physically confined in a particularly defined region with retention to their catalytic activities. Immobilized enzymes can be used repeatedly compared to free enzymes, which are unable to catalyze reactions continuously in the system. Immobilization also provides a higher pH value and thermal stability for enzymes toward synthesis. The main parameter influencing the immobilization is the support used to immobilize the enzyme. The support should have a large surface area, high rigidity, suitable shape and particle size, reusability, and resistance to microbial attachment, which will enhance the stability of the enzyme. The diffusion of the substrate in the carrier is more favorable on hydrophobic supports instead of hydrophilic supports. The methods used for enzyme immobilization also play a crucial role in immobilization performance. The combination of immobilization methods will increase the binding force between enzymes and the support, thus reducing the leakage of the enzymes from the support. The adsorption of lipase on a hydrophobic support causes the interfacial activation of lipase during immobilization. The adsorption method also causes less or no change in enzyme conformation, especially on the active site of the enzyme. Thus, this method is the most used in the immobilization process for industrial applications.

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.

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.