Enhancing the activity of cellulase enzyme using ultrasonic irradiations

The present work investigates the effect of low intensity ultrasonic irradiation on the cellulase activity. The effect on the kinetic and thermodynamic parameters as well as the molecular structure of cellulase enzyme was evaluated with the help of the chemical reaction kinetics model, Arrhenius equation, Eyring transition state theory, Michaelis-Menten equation, fluorescence spectroscopy and circular dichroism (CD) spectroscopy. It has been established that ultrasound had a positive effect on the activity of cellulase enzyme, though the selection of operating conditions played a crucial role in deciding the intensification. The maximum cellulase activity was observed at 17.33 W/cm(2) intensity and ultrasonic treatment time of 30 min, under which the enzyme activity was increased by about 25% over the untreated enzyme. After the ultrasonic treatment, thermodynamic parameters E-a, Delta H, Delta S and Delta G were reduced by 64.7%, 68%, 37.3% and 1.3%, respectively. In addition, fluorescence and CD spectra revealed that the ultrasonic treatment had increased the number of tryptophan on cellulase surface, and changed the molecular structure of cellulase enzyme favourably to provide more access to the active sites. (C) 2014 Elsevier B.V. All rights reserved.