Whole-cells or acetic acid bacteria were immobilized on the surface or carbon paste electrodes. The electrodes produced anodic currents due to the oxidation of ethanol, glucose, glycerol or fructose in neutral solutions at room temperature, in which enzymes in the bacterial cells catalyzed the oxidation of the substances by using the electrode as a final electron acceptor in the presence of electron transfer mediators.
Photosystem�U membranes containing photoreaction center were prepared from spinach leaves and immobilized on the surface of carbon paste electrodes containing quinone compounds. The electrode produced photo- current by illumination to oxidize water yielding oxygen.
Alcohol dehydrogenase containing PQQ and heme c as redox sites adsorbed on metal　electrodes to catalyze the electrochemical oxidation of ethanol in the absence of external mediators.