ANALYSIS OF SYNCHRONOUS GROWTH OF BAKERS-YEAST .2. COMPARISON OF MODEL PREDICTION AND EXPERIMENTAL-DATA

The population balance model for growth of baker's yeast with sustained synchronous oscillations is further evaluated to predict the permissible region of doubling times for the oscillations, the preferred region, and the preferred mode of oscillation. The comparison of model predictions and experimental data reveals that sustained oscillations can only exist in a region where the length of the parent cycle is increased, and the length of the daughter cycle is decreased, in reference to asynchronous growth. While the oscillation frequency is given by the lengths of the parent and daughter cycles together with the average doubling time, the preferred region of oscillations of a certain mode is determined by the length of the budding phase which also controls the oscillation amplitude and the increase in the average fraction of budding cells over asynchronous growth. From these two parameters, the preferred region of the oscillations is predicted and compares well to experimental data. The validity of the model is further tested by dynamic simulations of synchronous growth. The inherent structure of the model allows a clear separation of cell cycle related parameters and of the age distribution of the population, by which the identification of both from experimental data is greatly facilitated. The predicted tendency of the oscillation amplitude in dependency on the oscillation frequency is also in good agreement with experimental data for the CO2 evolution. The theoretical analysis shows that two different types of synchronous oscillations exist under excess of oxygen and oxygen limitation. The latter one, with oscillation periods greater than the doubling time, cannot be explained by the model.