Kinetic Modeling of β-Glucosidases and Cellobiohydrolases Involved in Enzymatic Hydrolysis of Cellulose

Abstract

The enzymatic hydrolysis of cellulose is still considered a main limiting step in the biological production of biofuel from lignocellulosic biomass. This step involves the action of at least three types of cellulose-degrading enzymes—endoglucanases, cellobiohydrolases, and β-glucosidases—acting in a synergistic way. This enzymatic cocktail, usually secreted by Trichoderma reesei at industrial scale, has already been well studied, and modeling of the hydrolysis kinetics widely investigated. However, most of these models are empirical and few of them distinguish the kinetic activity of each enzyme. This article provides a new way to design a functional kinetic model that dissociates the activity of β-glucosidases as a final homogeneous reaction, and the hydrolysis of cellulose by cellobiohydrolases in a heterogeneous phase. The predictive model combines a Michaelis-Menten (M-M) approach for the β-glucosidase action and a methodology based on Langmuir assumptions to describe the processive activity on solid substrate performed by cellobiohydrolases. We assess the influences of temperature, enzyme, and substrate concentration, as well as high glucose content. The suggested kinetic model allows for good prediction of all the experimental data.