Fed-batch cultivation

IntroductionChemical changes of a substrate accomplished by selected microorganisms Microorganisms are bacteria, yeast, and molds that feed on organic materials Food is required to growThe reactor is the heart of any fermentation

mode of operation Batch reactorContinuous reactorFed-Batch reactor

Batch reactorBatch processes operate in closed systems; substrate is added at the beginning of the process and products removed only at the end.

Continuous reactorBioreactors are operated continuously in a few bioprocess industries such as brewing, production of bakers' yeast and waste treatment.

Fed-Batch reactorIn fed-batch operation, intermittent or continuous feeding of nutrients is used to supplement the reactor contents and provide control over the substrate concentration.

Fixed volume fed-batch The culture volume is maintained constant by feeding the growth limiting substrate or withdrawal of a portion of the culture.

Variable volume fed-batch the volume changes with the fermentation time due to the substrate feed.

Advantages and disadvantages of the fed-batch reactors The conditions are under the control The production of by-products are avoidedReplacement of water loss by evaporation Dealing with toxic substrateNo additional special piece of equipment is required as compared with the batch fermentationThere is opportunity to optimize product synthesis

DisadvantagesIt requires previous analysis of the microorganism The quantities of the components to control must be above the detection limits of the available measuring equipment

The accumulation of non-producing or low-producing variants may result