Cyclic fed-Batch Culture

The life of variable volume fed-batch fermentation may be extended beyond the time it takes to fill the fermenter by withdrawing a portion of the culture and using the residual culture as the starting point for a further fed-batch process. The decrease in volume results in the significant increase in the dilute rate. This results in an increase in the specific growth rate. The increase is then followed by its gradual decrease as the quasi steady state is established. Such a cycle may be repeated several times resulting in a series of fed-batch fermentation. Thus, the organism would experience a periodic shift-up growth rate followed by a gradual shift-down. This periodicity in growth rate may be achieved in the fixed volume fed-batch systems by diluting the culture when the biomass reaches a concentration which cannot be maintained in aerobic conditions. Dilution results in decline of growth rate and increase of biomass, and once again the maximum sustainability in a vessel is obtained. Dilution would be achieved by withdrawing culture and refilling to the original level with sterile water or medium not containing feed substrate.