Abstract
An electrochemical measurement of yeast cell density and vitality was developed using 2,3,5-trimethyl-1,4-benzoquinone. 2,3,5-Trimethyl-1,4-benzoquinone was reduced most effectively to the corresponding hydroquinone by yeast cells. The hydroquinone produced was detected amperometrically on the glassy carbon electrode. Ethanol was essential for the effective metabolism of quinones by yeast cells. The maximum oxidative current was obtained at the ethanol concentration of 8–10% regardless of the strain of yeast. The promotion of the metabolism of quinones was thought to be based on the increase of plasma membrane permeability by ethanol molecules. A linear relationship between the oxidative current and cell density of yeast was obtained in the range of 6.4103–1.6106 cells/ml assay solution. During the cultivation of yeast cells the oxidative current showed an almost parallel change with that of glucose in yeast growth and fermentation, suggesting that the oxidative current change reflected the vitality of yeast cells.
