Highly selective butanol production by manipulating electron flow via cathodic electro-fermentation

Area of Science:

• Biotechnology
• Bioenergy
• Chemical Engineering

Background:

• Solventogenic Clostridia fermentation faces challenges in butanol selectivity and downstream processing costs.
• Addressing the energy crisis requires efficient and sustainable biofuel production methods.

Purpose of the Study:

• To develop and optimize a novel cathodic electro-fermentation (CEF) system mediated by methyl viologen (MV) for enhanced butanol production.
• To improve butanol selectivity and reduce production costs through electrochemical methods.

Main Methods:

• A cathodic electro-fermentation (CEF) system was designed and optimized using methyl viologen (MV) as a mediator.
• Fermentation conditions, including cathode potential, MV concentration, and glucose levels, were systematically adjusted.
• The effect of butyric acid as a co-substrate on butanol production was investigated.

Main Results:

• Optimal conditions (-0.60 V cathode potential, 0.50 mM MV, 30 g/L glucose) yielded 7.17 ± 0.55 g/L butanol with a yield of 0.32 ± 0.02 g/g.
• Supplementing with 4 g/L butyric acid increased butanol production to 13.14 ± 1.14 g/L, achieving 0.43 ± 0.01 g/g yield and 90.44 ± 1.66% selectivity.
• The polarized electrode and MV mediated unbalanced fermentation, suppressing hydrogen production and enhancing butanol formation.

Conclusions:

• The MV-mediated CEF system significantly improves butanol production efficiency and selectivity.
• This approach offers a promising strategy for cost-effective bio-butanol production.
• Electrochemical methods can effectively steer microbial fermentation towards desired product formation.