(149b) Synergistic Substrate Cofeeding Enables Rapid CO2 to Product Conversion

The continuous rise of atmospheric CO₂ from expanded use of fossil fuels has become a growing concern for the 21^st-century. A particularly valuable effort to remedy the imbalance between CO₂ generation and sequestration is the conversion of CO₂ into value-added products, which is beneficial to both the chemical economy and the environment. To achieve this biologically, a balanced supply of carbons, ATP, and reducing agents is required to enable rapid reductive metabolism and efficient CO₂ conversion. However, these components are commonly generated with varying efficiencies depending on metabolic pathways. Here we show that substrate mixtures with concurrent shortcut access to multiple pathways can optimally satisfy the biosynthetic requirements. By controlled cofeeding of superior ATP- and NADPH-generators as “dopant” substrates to cells primarily utilizing inferior substrates, we circumvent catabolite repression and tailor pathway usage to synergistically stimulate CO₂ reduction and its subsequent conversion into products. Glucose doping in Moorella thermoacetica CO₂ + H₂ cultures stimulates net carbon reduction (2.3 g-CO₂/g_cell/hr) into acetate by augmenting ATP synthesis via pyruvate kinase. Similarly, gluconate doping in Yarrowia lipolytica accelerates acetate-driven lipogenesis (0.046 g/g_cell/hr) by obligatory NADPH synthesis through the pentose cycle. Together, synergistic cofeeding produces CO₂-derived lipids with 38% energetic efficiency and demonstrates potential to convert CO₂ into advanced bioproducts.