Integrated Electromicrobial Production of Itaconic Acid From CO₂ at Liter-Scale Using Komagataella phaffii

Coupling electrochemical CO₂ reduction showing high selectivity with microbial biosynthesis offering metabolic versatility offers a promising strategy for converting CO₂ into value-added products. We present proof-of-concept of electromicrobially producing the platform chemical itaconic acid (IA) from CO₂ using a robust yeast chassis. The hybrid systems integrates in a single reactor electrochemical CO₂ reduction with microbial synthesis using a synthetic autotrophic Komagataella phaffii strain. Thereby CO₂ serves as carbon source while electrochemically generated formate from CO₂ provides reducing power to sustain microbial growth and drive IA production, reaching average titres of 110.1 mg·L^-1. While demonstrating the feasibility of directly coupling electrochemical and microbial processes within a single reactor, we reveal key challenges associated with integration, including limited system performance, variability in product titers, anodic oxidation of cathodic products, and constraints in energy efficiency. Despite these current limitations, our results establish the operational feasibility of integrated electromicrobial CO₂ conversion using industrial yeast and highlight critical parameters for process intensification.