Chapter 8 - Immobilization of Microbial Cells for the Production of Organic Acid and Ethanol

Abstract

This chapter covers the most applied techniques for immobilization of whole cells for production of organic acids and ethanol. The inhibition problems caused by high substrate and product concentrations are solved by an advanced technique of cell immobilization. Fermentation of sugar by Saccharomyces cerevisiae, for production of ethanol in an immobilized cell reactor (ICR), was successfully carried out to improve the performance of the fermentation process. The fermentation setup comprised a column packed with beads of immobilized cells. The immobilized S. cerevisiae was simply performed by the enriched cell culture harvested at exponential growth phase. The fixed-cell loaded ICR performed well in all stages of operation and the cells were entrapped by calcium alginate. In addition, in different experimental setup, the performance of immobilized Propionibacterium acidipropionici in a plug-flow tubular reactor for production propionic and acetic acids was evaluated. The organic acid production rate in the ICR was about four times that of the continuous stirred tank reactor (CSTR).