Energy harvesting using exoelectrogenic Shewanella oneidensis bacteria

Abstract

ABSTRACT In this study, we presented the results of experiments designed to harvest energy from a bioreactor where exoelectrogenic Shewanella oneidensis bacteria were inoculated in the electrolyte solution containing a carbon source. In the absence of metal electrodes, external electrical circuit, proton-exchange membrane (PEM) or any possible sources of electric potential in the reactor, we associate the electric potential gradients with the capability to transport electrons through the conductive nanowires. Shewanella oneidensis bacteria produce the nanowires in the environment with limited electron acceptors. The nanowires facilitate electron transfer from the oxidizing zone (lower part of the reactor) and the reducing zone (upper part of the reactor), generating electric potential difference. Transmission electron microscopy (TEM) imaging revealed nanowire formation in the electrolyte solution. After inoculation with the liquid medium amended with a carbon source, open-circuit voltages were produced in the range of 380–470 mV. A scaling-up approach was demonstrated by connecting two reactors in series, producing a maximum of 960 mV.