Destabilization of energy-metabolism oscillation in the absence of trehalose synthesis in the chemostat culture of yeast.

Energy-metabolism oscillation (EMO) in yeast is basically regulated by a feedback-loop of redox reactions and modulated by the metabolism of storage carbohydrates like glycogen and trehalose. We found that EMO of the transformant tps1Delta deleted of TPS1 encoding trehalose-6-phosphate synthase fluctuated unsteadily with a short wavelength in the absence of trehalose synthesis, while EMO was gradually destabilized with the wavelength increasing as storage in a frozen state was prolonged. During EMO, whereas the fluctuations in levels of the oxygen uptake rate, NAD(P)H and cAMP were attenuated, the glycerol level fluctuated with high amplitude and the levels of glycogen and ethanol fluctuated with similar amplitudes to those in the wild type. Thus, EMO barely operated in tps1Delta depending on the increase of glycerol synthesis as a source of inorganic phosphate in place of trehalose synthesis and fairly conserved fluctuation in the level of ethanol as a synchronizing agent.