Enhancing microbial CO₂ electrocatalysis for multicarbon reduction in a wet amine-based catholyte.

Area of Science:

• Biotechnology
• Electrochemistry
• Microbiology

Background:

• Microbial CO2 electroreduction (mCO2ER) uses microorganisms and cathodes to convert CO2 into valuable products.
• Limited CO2 solubility and availability in aqueous electrolytes hinder mCO2ER efficiency.
• Producing long-chain multicarbon compounds like carotenoids (~C40) remains challenging.

Purpose of the Study:

• To demonstrate efficient production of long-chain multicarbon reductants (carotenoids) via mCO2ER.
• To investigate the role of a wet amine-based catholyte medium in enhancing CO2 fixation.
• To optimize monoethanolamine (MEA) concentration for improved carotenoid biosynthesis.

Main Methods:

• Utilized electroautotroph bacteria in a wet amine-based catholyte medium for mCO2ER.
• Optimized monoethanolamine (MEA) concentration as a CO2 absorbent.
• Performed molecular biological analyses to understand carbon flux redirection.
• Measured faradaic efficiency for carotenoid production under varying MEA concentrations.

Main Results:

• Achieved efficient production of carotenoids (~C40) using MEA-assisted mCO2ER.
• Optimized MEA concentration enhanced CO2 fixation and redirected carbon flux towards carotenoid biosynthesis.
• Demonstrated a 4.5-fold increase in faradaic efficiency for carotenoid production compared to control.
• Identified MEA as a key factor in overcoming mass transport limitations.

Conclusions:

• MEA-assisted mCO2ER effectively addresses mass transport bottlenecks in bioelectrochemical systems.
• This approach enables highly efficient production of valuable products, such as carotenoids, from CO2.
• The study highlights a promising strategy for sustainable CO2 utilization and bioproduction.