Production of glutamate by two-phase fermentation

Abstract

On an industrial basis, amino acids are important components in pharmaceutical products and are widely used as food additives and flavor enhancers. The amino acids with the largest production volume is L-glutamate, which is the precursor for the synthesis of mono-sodium glutamate (MSG). Most of amino acid are now produced by batch fermentation processes. As one approach to improve the economics of processes, it is desirable to develop a continuous process. In the present work the continuous production of glutamate with immobilized cells were investigated. The living cells of Corynebacterium glutamicum ATCC 13058 were immobilized on k-Carrageenan gel matrix and immobilized gels were used as biocatalysts for the production of glutamate. The immobilized cells were activated for 48 hours in culture growth in order to give a full growth in gels. Using activated gels, experiments were carried out to find the effect of system environment such as pH and aeration rate on the glutamate productivity and cell growth. In air-circulated fermentor the continuous production of glutamate with immobilized cells was carried out. The effect of mean-residence time on the glutamate productivity and operational stability was investigated. The glutamate productivity profile showed a maximum at 10 hours mean-residence time, although the yield based on carbon source approaches a maximum as the mean-residence time increased beyond 10 hours. The maximum productivity was 0.265 g/l based on effluent flow rate. The performance of continuous whole cell reactor system was evaluated by measuring glutamate productivity for a period of 30 days and found to be far more superior to the performance of conventional batch reactor system.