Electrochemical bioassay system. Redox measurements of Escherichia coli growth by multichannel analyzer

The redox responses to growth of Escherichia coli, including potential changes with and without current drain, peak current and coulombic output as a function of electrode surface area, and the lag time from inoculation to mid-peak potential have been determined. Excellent reproducibility was established for replicate experiments under the uniform conditions prevailing in a multichannel electrochemical analyzer with automatic data acquisition. Bacterial generation of hydrogen from glucose followed by oxidation on the Pt anode appears to be the major electrode reaction. Concurrent measurements of absorbance and glucose consumption have been made. The following rate constants were obtained from kinetic studies: k (glucose consumption), k (E. coli growth), k (potential), k (current) and k (hydrogen generation). Further characterization of this bioelectrochemical system was derived from the studies of increasing concentrations of glucose, E. coli adsorption to anode, simulating redox responses with gaseous hydrogen and peroxide inhibition of the redox potential. Thus redox responses and kinetics measured in an E. coli fuel cell can be used to compare dose responses to agents and conditions that affect bacterial growth and environmental health.