Redox activity of single bacteria revealed by electrochemical collision technique

Several studies deal with the use of redox mediators for probing the electrochemical activity of a bacterium.

“In order to develop single-impact electrochemistry toward the identification of bacterial cells, several studies deal with the use of redox mediators for probing the electrochemical activity of the bacterium [32][33][34].”

By quantifying the charge flowing during current spikes, experiments have shown higher reactivity of E. coli cells (6.8×10^-18 mol of redox mediator reduced per bacterium) towards the TH mediator compared to B. subtilis (3.5×10^-18 mol of redox mediator reduced per bacterium).

“By quantifying the charge flowing during the current spikes, these experiments have shown a higher reactivity of E. coli cells (6.8×10 -18 mol of redox mediator reduced per bacterium) towards the TH mediator compared to B. subtilis (3.5×10 -18 mol of redox mediator reduced per bacterium) [33].”

Thionine can be reduced by the bacterial cell and when a single bacterium-TH complex collides onto the UME (5 μm carbon fiber), the reduced thionine is re-oxidized at +1.0 V vs Ag/AgCl and generates a current spike in the i-t curve.

“Thionine can be reduced by the bacterial cell and when a single bacterium-TH complex collides onto the UME (5 µm diameter carbon fiber), the reduced thionine is re-oxidized at an appropriate potential (+1.0 V vs. Ag/AgCl) and generate a current spike in the i-t curve [33].”

Thionine (TH+) has been used as a redox mediator electrostatically adsorbed on the bacterial surface, forming bacterium-TH complexes, to quantify the redox activity of Gram-negative E. coli and Gram-positive B. subtilis.

“In order to quantify the redox activity of two bacterial species: the Gram-negative E. coli and the Gram-positive B. subtilis, thionine (TH + ) has been used as a redox mediator electrostatically adsorbed on the bacterial surface, forming the bacterium-TH complexes [33].”

This work demonstrates an interesting method based on the electrochemical collision technique for quantifying bacterial redox activity with a mediator at the single-cell level, which is of great significance to better understand electron transfer processes in microorganisms and thus improve the design of microbial electrochemical technologies.

“This work demonstrates an interesting method based on the electrochemical collision technique for quantifying the bacterial redox activity with a mediator at the single-cell level, which is of great significance to better understand electron transfer processes in microorganisms and thus, improve the design of microbial electrochemical technologies [33].”