Redox-active molecules in bacterial cultivation media produce photocurrent

Renewable energy concepts such as microbial fuel cells (MFCs) present a promising, yet intrinsically complex electrochemical approach for utilizing bacteria as an electron source. In this work, we show that just the cultivation media for bacterial growth, which is based on yeast extract, is sufficient for generating electrical current in a bio-electrochemical cell (BEC). We apply cyclic voltammetry and 2-dimensional fluorescence spectroscopy to identify redox active molecules such as NADH, NAD⁺, and flavines that may play key roles in electron donation. Finally, we show that upon illumination, current production is enhanced 2-fold. This photocurrent is generated by a variety of metabolites capable of photochemical reduction, enabling them to donate electrons at the anode of the BEC.