Comparison of analysis methods for determination of the kinetic parameters in batch cultures

Alternative methods are presented to modelling the kinetics of microbial growth and substrate consumption in batch cultures. The maximum specific growth rate, μmax, the maximum specific substrate consumption rate, Rmax, and the saturation constant, Ks, were calculated for the growth of Candida utilis on glucose by using differential and integral analysis methods. The differential method was applied to the Monod equations. The integral analysis method was applied to a combination of those expressions and the empirical logistic equation to describe biomass formation. In this case, it was found that Rmax, μmax and Ks/S0 values were constant over a wide range of growth conditions. Both sets of calculated kinetic parameters enabled satisfactory simulation of the microbial growth and substrate consumption for aerobic batch cultures of C. utilis over a wide range of initial glucose concentration (S0 = 3.8–45 g/l). However, the kinetic parameters obtained by using the differential method were shown to be inadequate for the description of the time course of other main compounds in the process, including dissolved oxygen and carbon dioxide. In contrast, the integral analysis method allowed the complete description of the process dynamics. Comparison of data found in the literature for the growth of C. utilis with those predicted by using the kinetic parameters obtained from the integral analysis showed a reasonable agreement.