Interestingly, Geobacter sulfurreducens also called, “electricigens” [1] can form metabolically active biofilms greater than 50 μm thick which help in converting acetate to electricity [2]. Its property as microbial nanowires is important for long-range electron transfer through the biofilms. Cells at a distance from the anode remain viable and the electrically conductive ‘pili’ increase the thickness of the biofilm without reducing the efficiency, sometimes increases electricity production by 10-fold [2].
A recently discovered mutant strain, G. sulfurreducens KN400 [3, 4] can produce the highest known current densities in pure cultures. The possibilities of adapting this organism to produce even higher current densities are being evaluated