Stable Cellulolytic Enzymes and Their Application in Hydrolysis of Lignocellulosic Biomass

The effective utilization of lignocellulosic biomass for production of value-added products in bio-refineries mainly depends on their hydrolysis into constituent soluble sugars. Despite the commercial availability of lignocellulolytic enzymes, there are certain challenges in using these enzymes at an industrial scale which arise from their inherent characteristics. Hence, development of industrially potent and stable cellulolytic enzymes is of great importance. While a lot of emphasis has been given to produce the enzymes with high titre and productivity, the properties of these enzymes, which affect their performance in hydrolyzing lignocellulosic residues, have largely been ignored. The various properties that affect the hydrolysis are thermal stability, catalytic efficiency, non-specific adsorption, end-product inhibition resistance, and shear inactivation. This review discusses several approaches such as finding new enzymes from extremophiles, recombinant production of cellulolytic enzymes in industrial strains, directed evolution and mutagenesis, and formation of the enzyme aggregates that are being investigated to develop stable cellulase enzymes. The authors also suggest that for a meaningful information on the modified cellulolytic enzymes and their application in cellulose hydrolysis, they should be evaluated under practical process condition.