Fig. 4: Renewable bioproduction from both CO₂-derived e-formate and a lignin-derived organic acid stream containing formate.

a Electrochemical production of formate from CO₂. Catholyte solution was analyzed by HPLC-RID before and after electrochemical formate production and shows only one single peak corresponding to formate (chromatograms are offset for clarity). b Consumption of 100 mM formate during the bioproduction of mevalonate from electrochemically derived formate and optical density over the course of cultivation. Formate consumption mirrors cell growth during formatotrophic bioproduction of mevalonate (n = 4). c Mevalonate and isoprenol titers during two parallel bioproduction experiments from electrochemically produced formate; the maximum titers achieved were 22.9 (±3.0) mg/L mevalonate and 11.9 (±5.6) mg/L isoprenol. Mevalonate was produced from 100 mM electrochemically produced formate (n = 4). Isoprenol was produced from 120 mM electrochemically produced formate provided as a 60 mM initial concentration followed by another 60 mM addition at 72 h (n = 3). d Schematic diagram of mevalonate and isoprenol production from electrochemically reduced CO₂. Bioproducts are shown below in circles whose area correlates to the titer achieved at small scale (positive error denoted by larger concentric circle). e IPP bypass pathway from mevalonate to isoprenol. f Schematic diagram of mevalonate bioproduction from lignin-rich acid mixture. CO₂ is fixed into lignin through photosynthesis. Lignin is oxidatively depolymerized to formate and other small acids before bioproduction. g OD₆₀₀ of K4Me2 growing on formate-containing acid mixture derived from lignin. One part lignolysate was diluted with five parts M9 minimal medium to generate the growth medium (n = 4). h Initial concentrations and consumption of major components of the lignolysate (n = 4). i Initial concentrations and consumption of minor/trace components of the lignolysate (n = 4). j Mevalonate titer over the course of bioproduction from formate-containing lignolysate, a maximum titer of 32 (±5.8) mg/L was achieved in small scale (n = 4). Data represent the mean ± s.d. of biological replicates. Source data are provided as a Source Data file.