Extracellular electron transfer by Microcystis aeruginosa is solely driven by high pH

Abstract

Extracellular electron transfer (EET) by the cyanobacterium Microcystis aeruginosa was investigated. Observations indicate that EET onto an electrode poised at + 0.6 vs. standard hydrogen electrode (SHE) is triggered by high pH, more evidently at pH levels above 9. Light intensity does not appear to affect electricity generation, indicating that this may not be a “biophotovoltaic” process. The generated current density was amplified with stepwise pH increases from approximately 5 mA m−2 at pH 7.8 to 30 mA m−2 at pH 10.5, for dense (0.4 mg mL−1 dry weight) Microcystis aeruginosa suspensions with dissolved CO2 and O2 approaching equilibrium with atmospheric concentrations. The upsurge in curre..