Process development for production of succinic acid by immobilized cells

Abstract

Development of the fermentation process with immobilized Mannheimia succiniciproducens MBEL55E, LPK7 and ALK was studied for the biological succinic acid production. To increase the final succinic acid concentration and volumetric productivity packed bed reactor system was introduced. Batch culture process has low productivity because of the low concentration of the microorganisms in the system, product inhibition. On the other hand continuous culture is limited by cell washout. For high succinic acid concentration and high volumetric productivity in the fermentation process, immobilized cell was used to develop a bioreactor system that can maintain a high cell concentration. In this study fed batch culture and continuous culture with immobilized cell in a packed bed reactor were carried out to increase the final succinic acid concentration, volumetric productivity and yield. Free cell culture was carried out to compare there fermentation performances. Fed batch culture in a packed bed reactor was effective mode to increase the final succinic acid concentration and LPK7 strain was the most suitable strain. When the packing material was activated carbon the fermentation performance resulted in the production of 56.14 g/l of succinic acid. This value was 1.2 times higher than obtained by the fermentation using the tobermolite as packing material. In case of free cell fed batch culture of LPK7, final succinic acid concentration was 33.55 g/l. The highest succinic acid concentration was achieved by packed bed reactor system packed with activated carbon. Continuous culture in a packed bed reactor was efficient system to increase the succinic acid productivity and yield. The highest volumetric productivity was 3.22 g/l/h at dilution rate of 0.3 /h when the packing material was activated carbon. This productivity value was 2.48 times higher than that obtained by batch culture. When the packing material was tobermolite, the highest volumetric productivity was 2.69 ...