Microbial phenazine production enhances electron transfer in biofuel cells

Area of Science:

• Microbiology
• Electrochemistry
• Bioenergetics

Background:

• High-rate electron transfer to anodes in microbial fuel cells (MFCs) is crucial for power generation.
• The role of soluble redox mediators produced by bacteria in this process is not fully understood.
• Pseudomonas aeruginosa is a known bacterium with potential applications in MFCs.

Purpose of the Study:

• To investigate the mechanism of high-rate electron transfer in MFCs mediated by soluble redox compounds.
• To identify the specific compounds responsible for electron transfer in Pseudomonas aeruginosa.
• To explore the potential of these mediators to enhance electron transfer in other bacterial species.

Main Methods:

• Utilized microbial fuel cells (MFCs) with Pseudomonas aeruginosa strain KRP1 as the model organism.
• Generated mutant strains deficient in pyocyanin and phenazine-1-carboxamide synthesis.
• Measured power output and electron transfer rates under different conditions, including the addition of mediators.

Main Results:

• Pseudomonas aeruginosa utilizes pyocyanin and phenazine-1-carboxamide for efficient electron transfer to the anode.
• Anode presence stimulates pyocyanin production in P. aeruginosa.
• Mutant strains showed significantly reduced power output (5% of wild type) without these mediators.
• Addition of pyocyanin restored power output to 50% of the wild type.
• Pyocyanin enhanced electron transfer and growth for other bacterial species, a novel finding.

Conclusions:

• Pyocyanin and phenazine-1-carboxamide are key mediators for high-rate electron transfer in Pseudomonas aeruginosa within MFCs.
• These bacterial-derived electron shuttles can benefit co-cultured bacteria, improving overall MFC performance.
• The findings have significant implications for optimizing power generation in microbial fuel cells.