Scalable Electro-Biosynthesis of Ectoine from Greenhouse Gases

Converting greenhouse gases into valuable products has become a promising approach for achieving a carbon-neutral economy and sustainable development. However, the conversion efficiency depends on the energy yield of the substrate. In this study, we developed an electro-biocatalytic system by integrating electrochemical and microbial processes to upcycle CO₂ into a valuable product (ectoine) using renewable energy. This system initiates the electrocatalytic reduction of CO₂ to methane, an energy-dense molecule, which then serves as an electrofuel to energize the growth of an engineered methanotrophic cell factory for ectoine biosynthesis. The scalability of this system was demonstrated using an array of ten 25 cm² electrochemical cells equipped with a high-performance carbon-supported isolated copper catalyst. The system consistently generated methane at the cathode under a total partial current of approximately -37 A (~175 mmol_CH4 h^-1) and O₂ at the anode under a total partial current of approximately 62 A (~583 mmol_O2 h^-1). This output met the requirements of a 3-L bioreactor, even at maximum CH₄ and O₂ consumption, resulting in the high-yield conversion of CO₂ to ectoine (1146.9 mg L^-1). This work underscores the potential of electrifying the biosynthesis of valuable products from CO₂, providing a sustainable avenue for biomanufacturing and energy storage.