Decoupled electro-biosynthesis of high-value bioproducts from CO2 and N2.

Abstract

The conversion of atmospheric carbon dioxide (CO2) and nitrogen (N2) into high-value bioproducts offers a promising pathway for sustainable chemistry, food, and material production. However, existing approaches remain constrained by narrow product scopes, inefficient biological fixation, and poor scalability. Here, we present a spatially decoupled electro-biosystem that converts CO2 and N2 into poly-γ-glutamic acid (γ-PGA), while co-generating microbial biomass with cell-protein valorization potential. A Cu-N2 single-atom catalyst and plasma processes generate methane and nitrate from CO2 and N2, providing highly reduced carbon and oxidized nitrogen sources. The engineered methanotrophs heterologously expressing γ-PGA biosynthesis genes were designed to convert methane and nitrate into γ-PGA with a molecular weight of up to 700 kDa. Systematic optimization of carbon, nitrogen, and energy fluxes boosted γ-PGA titer by 125% to 142.84 mg L-1 in a 30 L bioreactor, accompanied by 9.47 g L-1 of cell protein. Importantly, the modular design allows the outputs of the electrocatalytic and plasma-assisted units to be adjusted according to the measured carbon, nitrogen, and oxygen demands of the biological module, thereby supporting supply-demand matching across the spatially decoupled system. Techno-economic analysis and life-cycle assessment identify key determinants of process economics and indicate the potential environmental benefits of the electro-biosystem, respectively. This study demonstrates a decoupled platform for high-value bioproduct production, providing a modular basis for process scale-up and advancing customizable, air-derived biomanufacturing from CO2 and N2.

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