Abstract
Impulse responses of specific rate of glucose consumption of a brewer's yeast (S. cerevisiae) v, that of cellular growth μ and that of alcohol production π to a pulse-feed of substrate were elucidated. By varying the concentration of glucose in the pulse-feed of substrate, the authors added the substrate to the system at different stages of batch cultivation and measured the changes in specific rates of the yeast cells.
The experiments showed that the responses of the specific rates were classified into two types according to the magnitude of increment in glucose concentration, ΔG. When ΔG was less than critical value ΔGc, the specific rates were not influenced by the pulse-feed of substrate. On the other hand, when ΔG was greater than ΔGc, the specific rates of the yeast cells were decreased immediately and it took some hours before the specific rates reached their maximum speed. The authors have obtained a relationship between ΔGc and a set of (G (τ-), X (τ-)), which indicate the concentration of glucose and that of cell mass at the time of substrate addition.
