Stable Cellulolytic Enzymes and Their Application in Hydrolysis of Lignocellulosic Biomass

Abstract

The effective utilization of lignocellulosic biomass for production of valueadded 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 them 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.

Halo-Tolerant And Thermostable Mechanisms of An Endoglucanase From Marine Aspergillus Niger

“…In terms of temperature, the enzymatic reaction mixtures (500 µl) including 50 µl properly diluted enzyme solution and 450 µl CMC-Na solution (1% (w/v) CMC-Na, 0.1 M sodium citrate/citric acid, pH 4.0) were incubated in water bath at different temperature (20,30,40,50, 60, 70 and 80°C) for 5 min. In terms of metal ions (5 mM and 10 mM), the enzymatic reaction mixtures (500 µl) including 50 µl properly diluted enzyme solution, 5 µl or 10 µl metal ions solution (NaCl, LiCl, AgNO 3 , MgCl 2 , CaCl 2 , NiCl 2 , CuSO 4 , ZnSO 4 , CrCl 2 , HgSO 4 , FeCl 3 , 0.5 M) and 445 µl or 440 µl CMC-Na solution (1% (w/v) CMC-Na, 0.1 M sodium citrate/citric acid, pH 4.0) were incubated in water bath at 50°C for 5 min.…”

“…Therefore, a higher reaction temperature is preferred during enzymatic hydrolysis of cellulose and the thermostability of cellulase is of crucial signi cance. Thermostable cellulases are widely available from many organisms, including fungi and bacteria (Patel et al 2019;Shuddhodana et al 2018). At present, large numbers of thermostable cellulases have been discovered, which are almost exclusively derived from thermophiles (Patel et al 2019;Shuddhodana et al 2018).…”

“…Thermostable cellulases are widely available from many organisms, including fungi and bacteria (Patel et al 2019;Shuddhodana et al 2018). At present, large numbers of thermostable cellulases have been discovered, which are almost exclusively derived from thermophiles (Patel et al 2019;Shuddhodana et al 2018). Study on mechanisms of thermostability is of great signi cance for directed evolution to obtain more thermostable enzymes.…”