| In order to model and control a bioprocess it is crucial to understand its dynamics. None of the past studies included complete kinetics of the L-lysine fermentation. The goal of this research was to investigate effects of process variables, such as dissolved oxygen, agitation, aeration, influent substrate concentration and rate, on the kinetics of L-lysine fermentation and to develop a fundamental model to optimize the bioreactor operation. Steady state CSTR data indicated that the specific rates of growth, substrate consumption, product formation and oxygen uptake were functions of the cell, substrate, product concentrations, and dissolved oxygen. The unstructured model developed incorporated the oxygen transfer and was able to predict both transient and steady state behavior of continuous culture as well as apparent effects of influent substrate concentration. The results are remarkable, because it is extremely difficult to simulate unbalanced growth by unstructured models developed from balanced growth data. The model was further adapted to batch culture with controlled dissolved oxygen and proved to simulate batch experiments at different initial substrate concentrations well. As expected, continuous culture gave the highest productivity. While many fundamental models were developed in the past for microbial cultures, little is known for the cell cultures. Therefore, the methodology developed in this research can be very useful for the cell cultures. |
