Enhanced microbial fuel cell (MFC) power outputs through Membrane Permeabilization using a branched polyethyleneimine

Area of Science:

• Microbiology
• Electrochemistry
• Biotechnology

Background:

• Microbial fuel cells (MFCs) harness microbial metabolism for electricity generation.
• Outer membrane permeability of microorganisms like E. coli influences MFC performance.
• Modulating outer membrane properties is a potential strategy to enhance MFC power density.

Purpose of the Study:

• To investigate the effect of outer membrane permeability on E. coli-based MFC power generation.
• To evaluate the efficacy of lipopolysaccharide (LPS) mutants and chemical permeabilizers in improving MFC performance.
• To elucidate the mechanisms by which permeabilizers enhance MFC output.

Main Methods:

• Utilized E. coli BW25113 lipopolysaccharide (LPS) mutants (ΔwaaC, ΔwaaF, ΔwaaG) to alter outer membrane permeability.
• Employed branched polyethyleneimine (BPEI) as a chemical permeabilizer.
• Measured power densities generated by MFCs using neutral red and benzyl viologen as mediators.
• Assessed bacterial cell zeta potential and anode adherence using scanning electron microscopy.

Main Results:

• E. coli LPS mutants ΔwaaC and ΔwaaF showed significantly higher power densities (5.6 and 6.9 mW/m², respectively) compared to wild-type (2.6 mW/m²).
• BPEI treatment increased E. coli power output to 29.7 mW/m², an 11-fold improvement over the control.
• BPEI enhanced MFC performance in mutant strains and with benzyl viologen mediator, increased zeta potential, and promoted bacterial auto-aggregation and anode adherence.

Conclusions:

• Outer membrane permeability is a critical factor for optimizing MFC power densities.
• Branched polyethyleneimine (BPEI) effectively enhances MFC performance by increasing membrane permeability and improving bacterial anode attachment.
• BPEI offers a dual benefit of increased power output and improved microbial electrode adhesion in MFCs.