An in situsurface electrochemistry approach towards whole-cell studies: the structure and reactivity of a Geobacter sulfurreducenssubmonolayer on electrified metal/electrolyte interfaces

A direct electron transfer process between bacterial cells of electrogenic species Geobacter sulfurreducens(Gs) and electrified electrode surfaces was studied to exploit the reactivity of Gssubmonolayers on gold and silver surfaces. A submonolayer of Gswas prepared and studied to explore specifically the heterogeneous electron transfer properties at the bacteria/electrode interface. In situmicroscopic techniques characterised the morphology of the Gssubmonolayers under the operating conditions. In addition, complementary in situspectroscopic techniques that allowed us to access in situmolecular information of the Gswith high surface selectivity and sensitivity were employed. The results provided clear evidence that the outermost cytochrome Cin Gsis responsible for the heterogeneous electron transfer, which is in direct contact with the metal electrode. Feasibility of single cell in situstudies under operating conditions was demonstrated where the combination of surface-electrochemical tools at the nano- and micro-scale with microbiological approaches can offer unique opportunities for the emerging field of electro-microbiology to explore processes and interactions between microorganisms and electrical devices.