Hydrogenase Activity Control at Desulfovibrio vulgaris Cell-Coated Carbon Electrodes: Biochemical and Chemical Factors Influencing the Mediated Bioelectrocatalysis

Hydrogen uptake and evolution reactions have been electrochemically measured using a glassy carbon electrode modified by a coating made of whole Desulfovibrio vulgaris Hildenborough cells. High cathodic and anodic catalytic currents have been obtained using methyl viologen as a mediator, which are reflecting hydrogenase activity inside the bacterial cell, in the production and uptake of hydrogen, respectively. The influence of various parameters, such as pH, ionic strength and nature of the mediator on the catalytic current values has been studied. An original strategy has been proposed in order to specify and understand the location of the hydrogenase activity. CV experiments have been performed using cell fractions of Desulfovibrio vulgaris Hildenborough, i. e., periplasmic, membrane and cytoplasmic fractions, respectively. Comparison has been made between the hydrogenase activities obtained from the electrochemical data in each cellular fraction and those measured using the pure isolated hydrogenases located in the different spaces of the cell.