Microbial Biofilm Voltammetry: Direct Electrochemical Characterization of Catalytic Electrode-Attached Biofilms

Abstract

While electrochemical characterization of enzymes immobilized on electrodes has become common, there is still a need for reliable quantitative methods for study of electron transfer between living cells and conductive surfaces. This work describes growth of thin (<20 m) Geobacter sulfurreducens biofilms on polished glassy carbon electrodes, using stirred three-electrode anaerobic bioreactors controlled by potentiostats and nondestructive voltammetry techniques for characterization of viable biofilms. Routine in vivo analysis of electron transfer between bacterial cells and electrodes was performed, providing insight into the main redox-active species participating in electron transfer to electrodes. At low scan rates, cyclic voltammetry revealed catalytic electron transfer between cells and the electrode, similar to what has been observed for pure enzymes attached to electrodes under continuous turnover conditions. Differential pulse voltammetry and electrochemical impedance spectroscopy also revealed features that were consistent with electron transfer being mediated by an adsorbed catalyst. Multiple redox-active species were detected, revealing complexity at the outer surfaces of this bacterium. These techniques provide the basis for cataloging quantifiable, defined electron transfer phenotypes as a function of potential, electrode material, growth phase, and culture conditions and provide a framework for comparisons with other species or communities.

Reference and counter electrode positions affect electrochemical characterization of bioanodes in different bioelectrochemical systems

“…To accomplish this, a potentiostat is used with a three-electrode setup consisting of a working electrode (WE), a counter electrode (CE), and a reference electrode (RE). This setup enables characterization of a single electrode separated from the contributions of other components to the total impedance of the cell (He and Mansfeld, 2009;He et al, 2006;Marsili et al, 2008). The RE is needed to set the potential of the WE in order to accurately characterize the WE performance.…”

Impedance and Thermodynamic Analysis of Bioanode, Abiotic Anode, and Riboflavin-Amended Anode in Microbial Fuel Cells

“…They indicates anode biofilm facilitated electron transfer to the anode surface. [9][10][11][12] Initial development of anode biofilm during the first five days decreased anodic charge transfer resistance by about 40% (from 2.6 to 1.5 kΩ cm 2 at 0.27 A/m 2 ) in a ferricyanide-cathode MFC, with increasing power density by about 120%. 11 Anodic charge transfer resistance decreased by ~75% (from 0.073 to 0.017 kΩ cm 2 at 2.63 A/m 2 ) in an air-cathode MFC, with increasing anodic capacitance during 70-day biofilm enrichment.…”

Towards patterned bioelectronics: facilitated immobilization of exoelectrogenic Escherichia coli with heterologous pili

“…(2008b) with slight modifications. In detail, the setup comprised a 6.4‐cm 2 ‐sized rectangular carbon cloth working electrode (Panex 30–SW08; Zoltek, Nyergesújfalu, Hungary) which was cleaned by incubation in 1 M NaOH, 1 M HCl, acetone (2×) and ddH 2 O (2×) and attached to a custom‐made polyether ether ketone barrel (Ø = 9 mm) using Pt wire (Ø = 0.05 mm).…”