AN ACCUMULATOR MODEL FOR ELECTRON TRANSPORT FROM MICROORGANISMS

Abstract

An accumulator model for microorganisms is proposed to describe the mechanism generating the electron flow from microbes. This model is based on the following central assumption: the microbial cell surface has a function to charge electrons released from inside the organism and to discharge them to the outside. Escherichia coli was used to test this model. The model was very useful in analyzing the time course of the current generated by the organism. To determine the suitability of the model, the consistency between the predictions based on the model and the observations was investigated by the following two types of experiments. (1) An experiment to increase the rate of electron charge from the respiratory chain of E. coli to the cell surface by adding succinic acid to the cell suspension. (2) An experiment to increase the rate of electron discharge from the cell surface to the outside by adding an anion exchange resin to the cell suspension. In both experiments the predictions and the observations were in good agreement. Consequently it was concluded that the accumulator model is useful in understanding the electrical characteristics of microbes. It was confirmed that an anion exchange resin can cause an electron transfer from the E. coli to the resin owing to an attractive force between the electron on the cell surface and the positive charge on the surface of the resin. A cation exchange resin, having a negatively charged surface, and an electrically neutral resin had little effect on the current.