Optimization and characterization of cold-active endoglucanase produced by Aspergillus terreus strain AKM-F3 grown on sugarcane bagasse

Abstract

The psychrotolerant microfungus Aspergillus terreus strain AKM-F3 (GenBank Accession No. KF417464) was investigated for the production of cold-active endoglucanase using sugarcane bagasse. The effects of different process parameters were studied for hyperproduction. Optimum production was found at 15 °C with an initial pH of 5.0 at 120 h. For enzyme production, 1 mM ZnCl2, 0.01% aspartate, 2% lactose, and 3% NaNO3 were regarded as potent inducers. The final production gave an activity 3.764-fold higher than the unoptimized conditions. The molecular weight of purified endoglucanase was 55 kDa, showing a 3.464-fold purification increase with a 23.925% yield having 75.279 U/mg of specific activity. The Km and Vmax values of the purified enzyme were found to be 0.37 mg/mL and 24.63 U/mg, respectively. The enzyme was more active at 35 °C and pH 4.0, whereas more stability was observed at 0 °C and pH 7.0. Ca2+, Mn2+, and all tested organic solvents were found to be activators of endoglucanase. EDTA had very low effect, whereas the most active inhibitor was sodium deoxycholate. The present study successfully produced a cold-active endoglucanase with novel properties that can be used for the degradation of cellulosic wastes in cold regions and the economically sound removal of unwanted extra microfibrils from cotton.