On the Nonlinear Dielectric Properties of Yeast Cells-Discussion from the Cases in which the Cells were Near and Away from the Electrodes-

Abstract

The harmonics of the response wave, the nonlinear dielectric properties of yeast cells, have particular patterns according to the biological activity of the cells, and the measurement of these patterns is a technique for determining the activity of living cells. In this study, we examined the generation of nonlinear dielectric properties by comparing data for the cases in which the cells were near and away from the electrodes with an electrochemical cell mounted with a membrane filter. Measurements were made with living yeast cells in the induction phase, the logarithmic growth phase, and the stationary phase, as well as with sterilized yeast cells. Our measurements of the nonlinear dielectric property of living yeast cells demonstrated that the pattern of harmonics varied depending on the growth phase of the cells. We found that harmonics appeared for yeast cells in every growth phase when the cells existed near the electrodes. When yeast cells existed away from the electrodes, the harmonics were barely apparent for living yeast cells in the induction and stationary phases and for sterilized yeast cells; however, living cells in the logarithmic growth phase (rapidly proliferating yeast cells) displayed substantial second and fourth harmonics. The activity state of yeast cells is one of the factors determining the harmonics pattern generated, and the particular relationship between the activity of the yeast cells and the electrodes affects the cells’ nonlinear dielectric properties.