Studies on immobilized keratinolytic protease from bacillus amyloliquefaciens au05

Abstract

Enzymes increase the rate of biochemical reactions by decreasing the activation energy. Unlike chemical catalysts, enzymes are specific and remain unaltered at the end of the reaction. Among microbial hydrolases, proteases account for 60% of the global enzyme market has an increased industrial demand for its wide range of applications along with ease of sustainable production. The industrial applications of proteases are challenging, due to destabilization of enzymes under operational and storage conditions with difficulty in recovery and reusability of the free enzymes which resulted in the employment of immobilization technology. Immobilization provides a microenvironment by confining the enzymes within the matrix thereby protecting them from robust conditions. They can be easily separated from the reaction products and can be reused further. The immobilization method and types of matrix are important parameters influencing the stability of enzymes. However entrapment of soluble enzymes within the matrix has the disadvantage of enzyme leaching and mass-transfer limitation which is effectively overcome by Cross-linked Enzyme Aggregates (CLEAs). The cross-linking of aggregates is a carrier-free immobilization technique which precipitates the crude enzymes to form insoluble enzyme aggregates with cross-linking agents such as glutaraldehyde. CLEAs enhance the amount of active enzymes by maintaining their tertiary structure. Electrospinning technique has also been employed to produce continuous nanofibers with high mechanical stability, interconnectivity and increased surface area. Thus various methods such as adsorption, cross-linking and entrapment methods along with recent techniques as CLEAs and electrospinning has been used in the study to enhance the operational stability and shelflife thereby preventing enzyme denaturation. During electrospinning, high electric forceresults in repulsive forces between the ionic groups of chitosan polymer hampering the nanofiber formation. This could be drastically reduced