In this application note, the differences between batch, fed-batch, and continuous fermentation and how these influence culture growth will be explained.
Batch fermentation in complex medium is a good starting point for fermentation beginners, and it is also the recommended method in the early stages of experimental design for strain selection and culture condition optimization. The growth improvement observed in batch fermentation in chemically defined medium compared to the one in complex medium proves the importance of medium composition in fermentation. Batch fermentation using an optimized medium composition is a feasible approach to
achieving decent biomass without complex handling.
When high biomass and product yield are the main goal (if the product yield is positively correlated with biomass), fed-batch fermentation should be considered, and it is also a very cost-effective operation. However, since fed-batch requires complex handling compared to batch fermentation, it poses more challenges for the operator.
Continuous fermentation is an operation which is also economically competitive. Once well established with a constant volume, continuous fermentation can reach a state when the specific growth rate is purely controlled by the feeding rate, which is very useful for growth control in both academic research and industrial production. It requires a thorough understanding of the bioprocess before one can successfully carry out continuous fermentation, and the operator needs to deal with the challenges in maintaining
sterility and productivity throughout the run which can last for weeks and months.
Overall, depending on the experimental needs and the laboratory settings, and with a brief estimate of the process budget and scheduling, we hope that this application note will help fermentation scientists to choose the ideal fermentation method to meet their unique needs.