Increased electrical output when a bacterial ABTS oxidizer is used in a microbial fuel cell

Area of Science:

• Microbial electrochemistry
• Bioenergy
• Microbiology

Background:

• Microbial fuel cells (MFCs) generate electricity from microbial oxidation of organic matter.
• Traditional MFCs rely on oxygen as the cathode oxidant, limiting efficiency.
• Novel oxidants are needed to improve MFC performance.

Purpose of the Study:

• To identify and characterize a bacterial oxidant produced in culture.
• To evaluate the performance of this oxidant in a two-chambered MFC.
• To assess its potential as a bio-cathode for enhanced electrical output.

Main Methods:

• Bacterial oxidant isolation and identification using DNA and FAME profiling.
• Characterization of oxidant properties: mass, heat stability, solubility, and substrate oxidation (ABTS).
• Performance testing in a two-chambered MFC with a proton exchange membrane and carbon cathode, using ABTS as a mediator.

Main Results:

• The oxidant was identified as originating from Burkholderia cenocepacia.
• The oxidant is heat-stable, soluble, and has a low molecular mass (<1 kD).
• In MFCs with ABTS mediator, the bacterial oxidant increased cell voltage 11-fold over atmospheric oxygen and 2.9-fold over ferricyanide.

Conclusions:

• Burkholderia cenocepacia produces a potent bacterial oxidant.
• This oxidant significantly enhances MFC performance when used with a mediator like ABTS.
• Microorganisms producing extracellular oxidants show potential as efficient bio-cathodes in MFCs.