TRANSIENT-BEHAVIOR OF CONTINUOUSLY CULTIVATED BAKERS-YEAST DURING ENFORCED VARIATIONS OF DISSOLVED-OXYGEN AND GLUCOSE-CONCENTRATIONS

NADH-dependent culture fluorescence is increasingly used for the chara cterization of the biological state of the cells, when their environme nt changes. For better interpretation of the signal variations time re solved measurements are necessary. Saccharomyces cerevisiae H620 strai n was cultivated on synthetic medium in continuous operation and time resolved response to variation of the dissolved oxygen and glucose con centrations were monitored by measuring the concentrations of cell mas s, glucose, ethanol, acetaldehyde, glycogen, trehalose, mannan, lipids , dissolved oxygen, O2 and CO2 in off-gas as well as the NADH-dependen t culture fluorescence. The time resolved ethanol concentration and fl uorescence intensity changes under different cultivation conditions ar e used to discuss the cell responses to their environmental change.