Mathematical model of direct ethanol production from starch in immobilized recombinant yeast culture

Abstract

A mathematical model of direct ethanol production from starch in immobilized recombinant amylase-producing yeast culture was proposed for estimating the dynamic behavior of cell growth, starch degradation, glucose accumulation, ethanol production, and glucoamylase synthesis by immobilized yeast. The application of the model was compared to the experiments of ethanol production from starch in batch and continuous cultures. The calculated values agreed well with experimental data, regarding concentration of cells, starch, ethanol, and glucoamylase. The profiles of concentration of starch, glucoamylase, cells, and ethanol in the gel bead for estimating the efficient ethanol production were calculated by the model. By comparing the ethanol productivity and the washout dilution rate in an immobilized cell culture with those in a free cell culture, it was confirmed that the immobilized cell culture had a higher ethanol productivity than the free cell culture and produced ethanol continuously with a dilution rate of 0.5 h-1, which is about 10 times larger than the washout rate in a free cell culture. © 2004 Elsevier B.V. All rights reserved.