Aggrandizing power output from Shewanella oneidensis MR-1 microbial fuel cells using calcium chloride

There are several interconnected metabolic pathways in bacteria essential for the conversion of carbon electron sources directly into electrical currents using microbial fuel cells (MFCs). This study establishes a direct exogenous method to increase power output from a Shewanella oneidensis MR-1 containing MFC by adding calcium chloride to the culture medium. The current output from each CaCl2 concentration tested revealed that the addition of CaCl2 to 1400 mu M increased the current density by >80% (0.95-1.76 mu A/cm(2)) using sodium lactate as the sole carbon source. Furthermore, polarization curves showed that the maximum power output could be increased from 157 to 330 mu W with the addition of 2080 mu M CaCl2. Since the conductivity of the culture medium did not change after the addition of CaCl2 (confirmed by EIS and bulk conductivity measurements), this increase in power was primarily biological and not based on ionic effects. Thus, controlling the concentration of CaCl2 is a pathway to increase the efficiency and performance of S. oneidensis MR-1 MFCs. Published by Elsevier B.V.