Fig. 2: Examination and optimal conditions for enCOH.

a, Selection of CODH and FDH for enCOH. ChCODH2, ChCODH4 and ToCODH were the candidate CODHs, and MeFDH1, RcFDH and TsFDH were the candidate FDHs. Using BV_ox, EV_ox and NAD⁺ as electron mediators, the formate (reverse triangles) productivity for each combination of CODHs and FDHs was determined over a 48 h period (data are presented as the mean ± s.d. of n = 3 replicates). b, Time course of the biotransformation through enCOH in a closed system. The percent of CO (circles) and CO₂ (triangles) was measured by GC and the formate (reverse triangles) amount was measured by HPLC over time. The yield (%, diamonds) of enCOH was calculated by dividing ∆formate into ∆CO (data are presented as mean ± s.d. of n = 3 replicates). c, Tracking of enCOH using isotopes ¹³CO and D₂O. ¹³CO gas (magenta) and D₂O (cyan) were used for testing, and the molecular weight of the formate produced via enCOH was determined by mass spectrometry (n = 1 replicate). A total of 98.9% (vol/vol) of the carbon was ¹²C and 99.9 % (vol/vol) of hydrogen was ¹H, leading most formate to have 45 g mol⁻¹ of molar mass^18,19.