A novel method for detecting microbial cells has been developed by applying cyclic voitammetry to a cell suspension of S. cerevlslae. A basal plane pyrolytic graphite electrode was employed as a working electrode. An anodic peak current appeared at 0.74 V vs. SSCE. A linear relationship was obtained between the peak current and the cell concentration in the range (0.1-1.9) × 108 cells·mL-1. The peak currents were reproducible with an average relative error of 4%. The peak currents per 108 cells were almost constant for cells harvested at an exponential growth period and a stational growth period. The peak current was not obtained from protoplasts of S. cerevlslae. It was shown that CoA existing in the cell wall mediated an electron transfer between the cells and the graphite electrode.
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