Hybrid Microbial-Enzymatic Electrosynthesis for De Novo Decanoic Acid Production from CO₂

The steady increase in atmospheric CO₂ levels is a key driver of anthropogenic climate change, prompting widespread global concern. In this context, the sustainable conversion of CO₂ into value-added chemicals represents an attractive route toward carbon-neutral manufacturing and green chemistry. Here, we developed a proof-of-concept hybrid microbial-enzymatic electrosynthesis system that combines microbial electrosynthesis (MES) and enzymatic electrosynthesis (EES) to convert CO₂ into decanoic acid under ambient conditions, using electrical energy. In the MES module, CO₂ was converted to acetate via the Wood-Ljungdahl pathway of Clostridium ljungdahlii, using H₂ produced by electrochemical water splitting as the electron donor. In the downstream EES module, acetate was transformed into acetyl-CoA, which was then elongated to decanoic acid through an in vitro reversed β-oxidation (rBOX) pathway driven by bioelectrocatalytic NADH regeneration. To verify the functional coupling between the two modules, ¹³C isotopic labeling was employed to trace carbon flow from CO₂ to acetate and further to decanoic acid, confirming that MES-derived carbon served directly as the precursor for downstream chain elongation in the EES module. Under optimized conditions, the hybrid MES-EES system produced 0.80 mM decanoic acid with 81.3% specificity. These results demonstrate the successful hybrid of MES and EES, enabling the de novo bioelectrosynthesis of decanoic acid from CO₂ and presenting a promising approach for coupling CO₂ resource utilization with renewable electrical energy.