Microbial Electrosynthetic Biohybrid System to Synergistically Supply Electrons and CO₂ to Rhodopseudomonas palustris for Lycopene Production.

Microbial electrosynthesis (MES) systems aim to use electroactive microorganisms (EAMs) to achieve electricity-driven CO₂ fixation for biosynthesis of multicarbon chemicals. However, the low efficiencies of extracellular electron transfer (EET) and CO₂ assimilation of EAMs remain the essential limiting factors that restrict performance of MES systems. Herein, we developed an electrosynthetic biohybrid system to synergistically supply electrons and CO₂ to Rhodopseudomonas palustris (an EAM) for lycopene biosynthesis. Intracellular carbon and energy fluxes were redirected by strengthening the lycopene biosynthesis pathway and blocking the nitrogen-fixation pathway, resulting in 23-fold increase in lycopene yield than that of the wild-type R. palustris. To enhance extracellular transfer of CO₂ and electrons to R. palustris, metal-organic frameworks (MOFs) with high CO₂ adsorption capacity were assembled with polydopamine on cell membrane to construct a biohybrid MES system, which produced 3.55 mg/L lycopene in two consecutive MES cycles, the highest lycopene production from CO₂. Electrochemical and transcriptomic analyses revealed that the biohybrid MES system stimulated microbial metabolism including EET, the Calvin-Benson-Bassham cycle and lycopene biosynthesis, thereby improving CO₂-to-chemical conversion. This study demonstrated directional supply of electrons and CO₂ to EAMs enabled high-performance MES systems, which also offered insights into the mechanisms underlying efficient CO₂ fixation and carbon-negative biomanufacturing.