Microbial Fuel Cell Based on Nitrogen-Fixing Rhizobium anhuiense Bacteria

Area of Science:

• Environmental Microbiology
• Bioelectrochemistry
• Renewable Energy Technologies

Background:

• Microbial fuel cells (MFCs) offer a sustainable energy source by harnessing microbial metabolism.
• Rhizobium anhuiense, a nitrogen-fixing bacterium, has potential as a biocatalyst in MFCs.
• Optimizing MFC performance requires understanding bacterial viability and electron transfer mechanisms.

Purpose of the Study:

• To investigate the efficacy of Rhizobium anhuiense as a biocatalyst in a double-chambered MFC.
• To evaluate the impact of glucose supplementation and menadione as a redox mediator on MFC performance.
• To determine the optimal concentration of menadione for maintaining bacterial viability and enhancing power output.

Main Methods:

• Construction and operation of an H-type MFC using Rhizobium anhuiense in modified Norris medium.
• Addition of glucose as a carbon source to the anode compartment.
• Incorporation of 2-methyl-1,4-naphthoquinone (menadione) as a redox mediator and assessment of its effect on power density and bacterial viability (OD600).

Main Results:

• The R. anhuiense-based MFC achieved an open-circuit voltage (OCV) of 635 mV and a power output of 1.07 mW m⁻².
• Glucose addition enhanced power output to 2.59 mW m⁻² at 281 mV.
• Menadione mediation increased OCV to 683 mV and power density to 4.93 mW cm⁻², with optimal bacterial viability observed at 1-10 μM menadione concentrations.

Conclusions:

• Rhizobium anhuiense is a viable biocatalyst for MFC applications.
• Glucose and menadione significantly improve MFC performance and power generation.
• Low concentrations of menadione (1-10 μM) support bacterial viability, enabling sustained MFC operation.