Microbial Biofilm Voltammetry
Defined conditions for studying microbial electron transfer to surfaces
While electrochemical characterization of immobilized enzymes on solid electrodes has become common, no standard methods are available to study electron transfer by whole organisms. We probe the electrochemistry of electron transfer via voltammetric protocols typically applied in protein film voltammetry and corrosion research.
Organisms are typically grown as biofilms on carbon fiber, glassy carbon, or microfabricated gold electrodes in 10 ml bioreactors, while maintaining strict anaerobic conditions. Electrode surfaces are polished to a defined roughness, and/or are oxidized to alter the carbon surface itself. Surface potential is controlled via a multichannel potentiostat; up to 16 independent channels can be monitored and probed in routine analyses, while three mobile electrochemical workstations are used for more detailed characterization of electrodes or supernatants.
New techniques for monitoring microbial electron transfer
Bioreactors are monitored frequently (and often automatically) through pre-programmed electrochemical analyses, including low scan rate cyclic voltammetry (LSRCV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). We have optimized protocols for these techniques, enabling detection of key midpoint potentials, and to increase peak separation. This work has systematically studied effects of variables such as electrode roughness and surface treatments on the rate and mechanisms of electron transfer to electrodes.
