Efficient production of medium chain fatty acids in microbial electrosynthesis with simultaneous bio-utilization of carbon dioxide and ethanol

Microbial electrosynthesis (MES) is a promising technology for chemicals production driven by renewable en-ergy. However, how the medium chain fatty acids (MCFAs) production in MES is affected by the method of chain elongation is not clear, and no direct evidence is provided yet for a simultaneous bio-utilization of CO2 and ethanol. In this study, different methods of chain elongation in MES reactors were investigated. During in-situ chain elongation, a maximum caproate concentration of 11.9 +/- 0.6 g L-1 was achieved, while the C6 specificity (56.4% +/- 0.5%) was much lower than that of ex-situ chain elongation (78.7% +/- 1.5%). Carbon distribution and reduction degree balance indicated a simultaneous bio-utilization of CO2 and ethanol, and it was validated by the isotope tracer technique. MCFAs-forming microbes, acetogens, and electrochemically active microorganisms were enriched. This study provides fundamental insights relevant to the carbon and electron fluxes driven by electricity.

Automated summary

This study investigates the impact of different chain elongation methods on MCFAs production in MES reactors and provides evidence for simultaneous bio-utilization of CO2 and ethanol. The results of this study provide fundamental insights into carbon and electron fluxes driven by electricity.