Kinetics and thermodynamics of catalysis and thermal inactivation of a novel α-amylase (Tp-AmyS) from Thermotoga petrophila

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.

Modifying Thermostability and Reusability of Hyperthermophilic Mannanase by Immobilization on Glutaraldehyde Cross-Linked Chitosan Beads

In the current study, the purified β-mannanase (Man/Cel5B) from Thermotoga maritima was immobilized on glutaraldehyde cross-linked chitosan beads. The immobilization of Man/Cel5B on chitosan beads was confirmed by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analysis. After immobilization, the protein loading efficiency and immobilization yield were found to be 73.3% and 71.8%, respectively. The optimum pH for both free and immobilized enzymes was found to be pH 5.5. However, the optimum temperature of immobilized Man/Cel5B increased by 10 °C, from 85 °C (free Man/Cel5B) to 95 °C (Immobilized). The half-life of free and immobilized enzymes was found to be 7 h and 9 h, respectively, at 85 °C owing to the higher thermostability of immobilized Man/Cel5B. The increase in thermostability was also demonstrated by an increase in the energy of deactivation (209 kJmol⁻¹) for immobilized enzyme compared to its native form (92 kJmol⁻¹), at 85 °C. Furthermore, the immobilized Man/Cel5B displayed good operational stability as it retained 54% of its original activity after 15 repeated catalytic reactions concerning its free form.