Figure 1. Solid electrode as electron donor for P. aestuarii growth.

(a) Cathodic current generated by a culture of P. aestuarii under light and dark conditions from a solid electrode polarized at −600 mV_Ag/AgCl. Cathodic current was observed in all three biological replicates of experiments with this setup. (b) Scanning electron micrograph of the surface of the electrode (scale bar, 2 μm), showing the typical prosthecate morphology (c) of P. aestuarii cells (scale bar, 500 nm). Micrograph representative of 16 recorded images. (d) Scanning electron micrograph of typical sulfide-cultured P. aestuarii cells on an isopore membrane filter (scale bar, 500 nm). Micrograph representative of 27 recorded images.