Continuous glutamate production using an immobilized whole-cell system

Abstract

For the purpose of saving the energy and raw materials required in glutamate fermentation, an immobilized whole-cell system was prepared and its performance in a continuous reactor system was evaluated. Corynebacterium glutamicum (a mutant strain of ATCC 13058) whole cell was immobilized in K-carrageenan matrix and the gel structure was strengthened by treatment with a hardening agent. The effective diffusivities of carrageenan gel for glucose and oxygen were found to decrease significantly with an increase in carrageenan concentration, while the gel strength showed an increasing trend. Based on the physical and chemical properties of carrageenan gel, the immobilization method was improved and the operation of the continuous reactor system was partially optimized. In an air-stirred fermentor, the continuous production of glutamate was carried out. The effect of the dilution rate on glutamate production and operational stability were investigated. The performance of the continuous whole-cell reactor system was evaluated by measuring glutamate productivity for a period of 30 days; it was found to be far superior to the performance of conventional batch reactor systems using free cells.