Electroautotrophy of Thioalkalivibrio nitratireducens

The electrochemical behavior and electro-autotrophy of a halo-alkaliphilic chemo-autotrophic Ectothiorhodospiraceae isolated from a soda lake, Thioalkalivibrio nitratireducens, were investigated using electrochemical methods and confocal fluorescence microscopy. The electrocatalysis of oxygen reduction was observed at -0.25 V/Ag/AgCl (-0.055 V/ SHE) with bioelectrodes polarized at -0.3 V/Ag/AgCl (-0.105 V/SHE), displaying a maximum catalytic current density of -620 mA m^-2 (voltammetry). No catalytic signal toward nitrate reduction was observed under anaerobia. The microscopic observation of the polarized electrodes compared to non-polarized ones, however, revealed a bacterial proliferation both under aerobic and anaerobic conditions, demonstrating the ability of Tv. nitratireducens to grow with the polarized electrode as sole electron source.