Microbial proteases: A next generation green catalyst for industrial, environmental and biomedical sustainability

Proteases are among the most important classes of hydrolytic enzymes and occupy a key position due to their applicability in both physiological and commercial fields. They are essential constituents of all forms of life, including plants, animals, and microorganisms. However, microorganisms represent an attractive source for protease secretion due to their high productivity in a relatively short time and limited space requirements for cultivation, amongst others. Microbial proteases are produced by submerged or solid-state fermentation process during post-exponential or stationary growth phase. The production of these biocatalysts by microbes is influenced by nutritional and physicochemical parameters. Downstream recovery of high-value enzyme products from culture supernatant using suitable techniques is imperative prior to further use of the biocatalysts. Immobilization of these enzymes in appropriate matrices permits reusability, reclamation, enhanced stability and cost-effectiveness of the biocatalysts. The catalytic properties of microbial proteases help in the discovery of enzymes with high activity and stability, over extreme temperatures and pH for utilization in large-scale bioprocesses. This review provides insights into microbial proteases taking cognizance of the bioprocess parameters influencing microbial proteases production coupled with methods employed for protease purification as well as the immobilization and biochemical properties of the biocatalysts for potential biotechnological applications.