Electrocatalytic CO₂ Reduction Coupled to Formate Fermentation: An Electro-Bio Cascade Approach in Biocompatible...

Area of Science:

• Biotechnology
• Electrochemistry
• Microbiology

Background:

• Integrating electrochemical CO2 reduction with microbial fermentation offers a pathway to convert CO2 into valuable chemicals.
• Challenges exist at the interface, requiring electrolytes compatible with both efficient CO2 reduction and microbial growth.

Purpose of the Study:

• To investigate various electrolytes for coupling CO2 electroreduction to formate with formate fermentation by Methylorubrum extorquens TK 0001.
• To evaluate electrolyte performance based on formate production and microbial growth.

Main Methods:

• Screening of different electrolytes for CO2 electroreduction and formate fermentation.
• Evaluation of microbial growth and formate production in various buffer conditions.
• Optimization of electrolyte concentration (potassium phosphate, KPi) for microbial tolerance and CO2 electrolysis.

Main Results:

• A phosphate-based buffer demonstrated superior compatibility for the integrated system.
• Optimal microbial growth of Methylorubrum extorquens TK 0001 occurred at 0.1 mol L-1 KPi.
• The system achieved high formate production (2.0 mol L-1 in 48 h) and efficient formate fermentation (biomass yield of 107 mg CDW gformate-1).

Conclusions:

• Electrolyte composition and concentration are critical for balancing efficient CO2 electroreduction and stable microbial fermentation.
• Optimizing the electrochemical-biological interface allows direct utilization of CO2-derived formate for sustainable microbial production.
• This integrated approach presents a promising scalable route for industrial biotechnology applications.