Preparation and characterization of sugilite glass from basalt for α-amylase immobilization, statistical optimization of the immobilization process and description of free and immobilized enzyme

Heterologous expression of calcium-independent mesophilic α-amylase from Priestia megaterium: Immobilization on genipin-modified multi-walled carbon nanotubes and silica supports to enhance thermostability and catalytic activity

α-Amylases, constituting a significant share of the enzyme market, are mainly synthesized by the genus Bacillus. Enzymes tailored for specific industrial applications are needed to meet the growing demand across a range of industries, and thus finding new amylases and optimizing the ones that already exist are extremely important. This study reports the successful expression, characterization and immobilization of P. megaterium α-amylase (PmAmy) in E. coli protein expression systems. The recombinant PmAmy has a molecular weight of 56 kDa and its in silico predicted model structure presents a monomer composed of three domains, like most amylases. Regarding long-term storage, PmAmy remained 60 % active after 6 weeks of storage at -20 and -80 °C indicating its stable storage at low temperatures. PmAmy was found to be Ca2+ ion-independent for both catalytic activity and thermostability while Mn2+ enhanced activity in a concentration-dependent manner. The optimum characteristic working conditions of PmAmy were measured as pH 7.0 and 40 °C. Immobilizing PmAmy significantly improved its thermal stability, increasing its resistance to thermal denaturation by at least 4.1-fold. Kinetic analyses revealed that the KM and Vmax values of free PmAmy were 0.1 mg mL-1 and 556 U mg-1, respectively while immobilization resulted in an increase for both the KM and Vmax values. Kinetic analysis revealed enhanced activity for the Ca2+-independent immobilized enzyme, making it suitable for industrial applications particularly starch processing requiring moderate thermostability without the need for Ca2+ ions.

Immobilization of recombinant serine protease from Virgobacillus natechei FarDT on amino graphene-chitosan biocompatible nanohybrid for enhancing pH and thermal stability

The serine protease gene was heterologously expressed in Escherichia coli BL21 (DE3) using the PET 28a vector. The purified enzyme was immobilized on a nanohybrid of amino graphene and chitosan. The characterization of synthesized nanohybrids and immobilized enzymes was confirmed by Fourier transform infrared (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), and field emission scanning electron microscopy (FE-SEM). Immobilization increased the temperature optimum from 60 to 70 °C for both free and immobilized enzymes, while the optimal pH of the enzymes did not change post-immobilization (pH 8). The immobilized biocatalyst significantly enhanced thermal stability, as well as enzyme stability at significant pH ranges. After 30 days of storage, the immobilized enzymes exhibited approximately 83 % of their relative activity, while the free protease retained only 56 % of its initial activity. Stabilization also altered the kinetic parameters (increasing Km, decreasing Kcat/Km, and Vmax) and thermodynamic parameters (increasing enzyme half-life and activation energy). The study's outcomes represent a significant advancement in the realm of enzyme synthesis and its stabilization using several combined technologies, including enzyme production with recombinant DNA technology based on gene synthesis, and its stabilization using a hybrid substrate synthesized from nanomaterials. Based on these findings, the immobilized recombinant enzyme has high potential for industrial use as an efficient and stable biocatalyst.

Improvement of combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase and maltogenic amylase by functionalization of cross-linker for maltooligosaccharides synthesis

Combined cross-linked enzyme aggregates of cyclodextrin glucanotransferase (CGTase) and maltogenic amylase (Mag1) from Bacillus lehensis G1 (Combi-CLEAs-CM) were successfully developed to synthesis maltooligosaccharides (MOS). Yet, the poor cross-linking performance between chitosan (cross-linker) and enzymes resulting low activity recovery and catalytic efficiency. In this study, we proposed the functionalization of cross-linkers with the integration of computational analysis to study the influences of different functional group on cross-linkers in combi-CLEAs development. From in-silico analysis, O-carboxymethyl chitosan (OCMCS) with the highest binding affinity toward both enzymes was chosen and showed alignment with the experimental result, in which OCMCS was synthesized as cross-linker to develop improved activity recovery of Combi-CLEAs-CM-ocmcs (74 %). The thermal stability and deactivation energy (205.86 kJ/mol) of Combi-CLEAs-CM-ocmcs were found to be higher than Combi-CLEAs-CM (192.59 kJ/mol). The introduction of longer side chain of carboxymethyl group led to a more flexible structure of Combi-CLEAs-CM-ocmcs. This alteration significantly reduced the Km value of Combi-CLEAs-CM-ocmcs by about 3.64-fold and resulted in a greater Kcat/Km (3.63-fold higher) as compared to Combi-CLEAs-CM. Moreover, Combi-CLEAs-CM-ocmcs improved the reusability with retained >50 % of activity while Combi-CLEAs-CM only 36.18 % after five cycles. Finally, maximum MOS production (777.46 mg/g) was obtained by Combi-CLEAs-CM-ocmcs after optimization using response surface methodology.

Covalent immobilization of β-galactosidase using a novel carrier alginate/tea waste: statistical optimization of beads modification and reusability

β-galactosidase has been immobilized onto novel alginate/tea waste gel beads (Alg/TW) via covalent binding. Alg/TW beads were subjected to chemical modification through amination with polyethyleneimine (PEI) followed by activation with glutaraldehyde (GA). Chemical modification parameters including PEI concentration, PEI pH, and GA concentration were statistically optimized using Response Surface methodology (RSM) based on Box-Behnken Design (BBD). Analysis of variance (ANOVA) results confirmed the great significance of the model that had F value of 37.26 and P value < 0.05. Furthermore, the R2 value (0.9882), Adjusted R2 value (0.9617), and predicted R2 value (0.8130) referred to the high correlation between predicted and experimental values, demonstrating the fitness of the model. In addition, the coefficient of variation (CV) value was 2.90 that pointed to the accuracy of the experiments. The highest immobilization yield (IY) of β-galactosidase (75.1%) was given under optimized conditions of PEI concentration (4%), PEI pH (9.5), and GA concentration (2.5%). Alg/TW beads were characterized by FT-IR, TGA, and SEM techniques at each step of immobilization process. Moreover, the immobilized β-galactosidase revealed a very good reusability as it could be reused for 15 and 20 consecutive cycles keeping 99.7 and 72.1% of its initial activity, respectively. In conclusion, the environmental waste (tea waste) can be used in modern technological industries such as the food and pharmaceutical industry.

Challenges and prospects of microbial α-amylases for industrial application: a review

α-Amylases are essential biocatalysts representing a billion-dollar market with significant long-term global demand. They have varied applications ranging from detergent, textile, and food sectors such as bakery to, more recently, biofuel industries. Microbial α-amylases have distinct advantages over their plant and animal counterparts owing to generally good activities and better stability at temperature and pH extremes. With the scope of applications expanding, the need for new and improved α-amylases is ever-growing. However, scaling up microbial α-amylase technology from the laboratory to industry for practical applications is impeded by several issues, ranging from mass transfer limitations, low enzyme yields, and energy-intensive product recovery that adds to high production costs. This review highlights the major challenges and prospects for the production of microbial α-amylases, considering the various avenues of industrial bioprocessing such as culture-independent approaches, nutrient optimization, bioreactor operations with design improvements, and product down-streaming approaches towards developing efficient α-amylases with high activity and recyclability. Since the sequence and structure of the enzyme play a crucial role in modulating its functional properties, we have also tried to analyze the structural composition of microbial α-amylase as a guide to its thermodynamic properties to identify the areas that can be targeted for enhancing the catalytic activity and thermostability of the enzyme through varied immobilization or selective enzyme engineering approaches. Also, the utilization of inexpensive and renewable substrates for enzyme production to isolate α-amylases with non-conventional applications has been briefly discussed.

Computational Insights into the Selecting Mechanism of α-Amylase Immobilized on Cellulose Nanocrystals: Unveiling the Potential of α-Amylases Immobilized for Efficient Poultry Feed Hydrolysis

The selection of an appropriate amylase for hydrolysis poultry feed is crucial for achieving improved digestibility and high-quality feed. Cellulose nanocrystals (CNCs), which are known for their high surface area, provide an excellent platform for enzyme immobilization. Immobilization greatly enhances the operational stability of α-amylases and the efficiency of starch bioconversion in poultry feeds. In this study, we immobilized two metagenome-derived α-amylases, PersiAmy2 and PersiAmy3, on CNCs and employed computational methods to characterize and compare the degradation efficiencies of these enzymes for poultry feed hydrolysis. Experimental in vitro bioconversion assessments were performed to validate the computational outcomes. Molecular docking studies revealed the superior hydrolysis performance of PersiAmy3, which displayed stronger electrostatic interactions with CNCs. Experimental characterization demonstrated the improved performance of both α-amylases after immobilization at high temperatures (80 °C). A similar trend was observed under alkaline conditions, with α-amylase activity reaching 88% within a pH range of 8.0 to 9.0. Both immobilized α-amylases exhibited halotolerance at NaCl concentrations up to 3 M and retained over 50% of their initial activity after 13 use cycles. Notably, PersiAmy3 displayed more remarkable improvements than PersiAmy2 following immobilization, including a significant increase in activity from 65 to 80.73% at 80 °C, an increase in activity to 156.48% at a high salinity of 3 M NaCl, and a longer half-life, indicating greater thermal stability within the range of 60 to 80 °C. These findings were substantiated by the in vitro hydrolysis of poultry feed, where PersiAmy3 generated 53.53 g/L reducing sugars. This comprehensive comparison underscores the utility of computational methods as a faster and more efficient approach for selecting optimal enzymes for poultry feed hydrolysis, thereby providing valuable insights into enhancing feed digestibility and quality.

Protease immobilization on a novel activated carrier alginate/dextrose beads: Improved stability and catalytic activity via covalent binding

Protease from Bacillus thuringiensis strain-MA8 was successfully immobilized onto activated Alginate/dextrose (Alg/dex) beads as a new carrier with immobilization yield 77.6 %. The carrier was characterized using Scanning electron microscopy and Fourier transforms infrared spectrophotometer at every step of the immobilization process. Immobilized protease showed an increase of 10 °C in the optimum temperature compared to the free enzyme. However, the optimum pH for both the free and the Alg/dex/protease was found to be 8. The lower activation energy and deactivation rate constant and the higher half-life time and D-value confirm that the new Alg/dex carrier is suitable for promoting enzyme stability. The raise in thermal stability is also shown by the increased deactivation energy of the Alg/dex/protease compared to its free form by 1.47-fold. Likewise, the enzyme immobilization enhancement of Alg/dex/protease was accompanied by a marked increase in enthalpy and Gibbs free energy. The negative entropy for both free and Alg/dex/protease indicates that the enzyme is more stable in thermal deactivation. The Km and Vmax for the Alg/dex/protease were 2.05 and 1.22-times greater than the free form. Furthermore, Alg/dex/protease displayed good reusability as it retained 92.7 and 52.4 % of its activity after 8 and 12 hydrolysis cycles.