Cyclic fed batch

Keller, R. and Dunn, I. J., Computer simulation of the biomass production rate of cyclic fed batch continuous culture, J. Appl. Chem., BiotechnoL, 28, 508-514, 1978. 

Repeated fed-batch process (cyclic fed-batch process)... 

To develop analytical models that describe the performance of a cyclic enzyme system (herein termed the basic system) and a cyclic enzyme system with an external inhibitor (termed the extended basic system) when operated in different modes as a fed-batch reactor or a continuous reactor. These models enable us to design systems and select operational conditions according to needs. 

The fed-batch and batch cultivation systems share the same cleaning and sterilization process in which the bioreactor operation is stopped and the bioreactor is emptied. This stoppage creates considerable costs and operational downtime. The repeated or cyclic system, which can be applied to both batch and fed-batch cultivation systems, may be installed in order to maximize the productivity. The cyclic cultivation system does not enter the cleaning and sterilization process, but rather empties a portion of the bioreactor while preserving part of the batch for the next cycle. Another method to increase productivity is cell retention techniques such as fluidized beds, membranes, or external separators. These options allow multiple cycles without cleaning and sterilization, which is initiated only if it is deemed that mutation risks exceed tolerable levels (Bellgardt, 2000b). 

DISCONTINUOUS DISCONTINUOUS CONTINUOUS CYCLIC or CONST.VOLUME FED BATCH FED BATCH PERIODIC DCSTR... 

The fed-batch technique of cultivation is limited by fermenter volume because the volume of fermentation broth increases after each substrate addition. This disadvantage can be avoided by application a cyclic feeding strategy [9-11] which allows one to control the synchrony of individual cell development [9] by the limiting substrate concentration. The preliminary simulation results on a computer show that this type of environmental control of continuous production of exocellular hydrolytic enzymes based on our model is very promising. 

Vu-Trong and P.O. Grady, Stimulation of tylosin productivity resulting from cyclic feeding profiles in fed-batch cultures, Biotechnol. Lett., 4 725 (1982)... 

Tests were carried out at 25°C and at initial pH 6.9. Cultures in the liquid medium were incubated in 50 mL Falcon tubes, continuously shaked at 220 rpm. Each culture contained a fresh Pseudomonas sp. 0X1 colony in 10 mL of medium. The airlift with 10 g of pumice was sterilized at 121°C for 30 min and then housed in a sterile room. One-day culture was transferred to the reactor and, after a batch phase, liquid medium with phenol as the only carbon source was continuously fed. The reactor volume V was fixed at 0.13 L. Aerobic conditions were established sparging technical air. Under these conditions microorganism started to grow immobilized on the solid s support. When immobilized biomass approached steady state, cyclic operation of the airlift was started by alternating aerobic/anaerobic conditions. 

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