Hydrolysis of Soluble Starch by Glucoamylase Immobilized on Ceramic Monolith

To evaluate the effectiveness of a ceramic monolith (mean pore diameter, 15 μm) as a support for the immobilized enzyme that catalyzes the hydrolysis of a high-molecular weight substrate, the hydrolysis of soluble starch (average molecular weight, 30 000) by use of glucoamylase from Rhizopus delemar was carried out at 50°C, pH 4.5. By observing the initial reaction rate in a batch reactor, wherein a fan-shaped piece of the immobilized enzyme monolith was fixed around a stirrer shaft, the pore diffusion resistance was found to be negligible when the concentration of starch exceeds 89 g/l. The simplified kinetic model, previously proposed, that assumed kinetic parameters as changing linearly with reduction of average molecular weight of substrate was also useful for simulating the immobilized enzyme system, regardless of batch or continuous mode, described in this paper.