Figure 3.

Absorbance data of a G. sulfurreducens biofilm depleted of electron donors at a current density of 450 μA cm⁻². While poising the electrode at +0.24 V, acetate was added stepwise at 15 min intervals. Even when the respiration rate was less than 10 % of maximum (<100 μm acetate), accumulation of electrons in cytochromes was still detected.