Continuous acetate production through microbial electrosynthesis from CO₂ with microbial mixed culture

BACKGROUND: Microbial electrosynthesis represents a promising approach for renewable energy storage in which chemically stable compounds are produced using CO₂ as feedstock. This report describes the continuous production of acetate through microbial electrosynthesis from CO₂ and assesses how the production rates could be increased. RESULTS: A continuous acetate production rate of 0.98mmol C L_NCC^-1 d^-1 was obtained using CO₂ as feedstock and with pH control around 5.8. These conditions increased substrate availability and favoured microbial electrosynthesis. Cyclic voltammograms demonstrated the electroautotrophic activity on the biocathode surface, which increased with pH control and caused current demand and acetate production rate to rise exponentially. CONCLUSION: pH decrease was shown to be an effective strategy to increase substrate availability and enhance microbial electrosynthesis. By making microbial electrosynthesis a feasible technology, CO₂ could become an alternative feedstock for the carboxylate platform.