Effect of alkali pretreatment on cellulase hydrolysis of wheat straw:: Kinetic study

The most efficient way to hydrolyse cellulose from wheat straw is by enzymic hydrolysis, which can be improved by different pretreatments of the substrate. The enzyme kinetics of alkali (sodium hydroxide) pretreated wheat straw was studied using different concentrations of a commercial cellulase enzyme (6.25-75 g/L). This pretreatment increased hydrolysis compared to untreated wheat straw. The influence of enzyme concentration on the production of reducing sugars was studied from two different theoretical approaches. In the first, the hydrolysis model and kinetic parameters (maximal velocity, V-emax,V- and half-saturation constant, K-e) were determined from initial velocities by an alternative approach to the classical Michaelis-Menten equation. In the second, the Chrastil approach is used, which is the study of all the time values from the rate of product formation, taking into account that in a heterogeneous system, these reactions are diffusion limited and the time curves depend strongly on the heterogeneous rate-limiting structures of the enzyme system. (c) 2005 Elsevier Ltd. All rights reserved.