The equation-based models presented in Chapter 6 require specific rates of cell growth, substrate consumption, intermediate formation, and product formation. In this chapter, we will review the traditional methods of determining these specific rates and present a method of determining without taking time derivatives the net specific rates utilizing fed-batch cultures. Traditional methods of generating experimental data involve using primarily shake flasks (batch reactors) and, secondarily, continuous flow reactors. A new method utilizes fed-batch cultures with constant feed rates and does not require differentiation of experimental data.

It is best to generate experimental data using the type of operation that is being contemplated; that is, if a batch culture is the ultimate mode of operation, it is best to generate specific rate data using batch cultures, and if a fed-batch operation is to be used, then it is best to use fed-batch operation to generate specific rate data. Compared to chemical reactions, microbial kinetics are complex and time variant so that frequently, rate data obtained at steady state operations may not apply well to dynamic operations.