Impedance Analysis of PCA, MR-1, and their Coculture in Bioeletrochemical Systems

The impedance signatures of duplicate defined-culture bioanodes enriched with Geobacter sulfurreducens, Shewanella oneidensis, and their coculture were analyzed in microbial electrolyte cells. The PCA anodes and the MR-1 anodes had intracellular impedance (RIN) a few orders of magnitude larger than extracellular impedance (REX), indicating intracellular exoelectrogenic process was a rate-limiting step. RIN and REX of the PCA anodes were about 9-fold and 31 to 55-fold lower than those of the MR-1 anodes, respectively. Total capacitance was dominated by intracellular capacitance (CLF) in both PCA and MR-1. Total capacitance of the MR-1 anodes was ~2.5 fold lower than for the PCA anodes. Different morphological features of high-frequency arcs were found in the defined cultures, suggesting impedance spectra can be utilized as electrochemical signature of different exoelectrogenic pathways.