Fig. 4

Replacement of butyryl-CoA dehydrogenase (Bcd) with trans-enoyl-CoA reductase (Ter) does not substantially improve butanol levels. a A schematic showing the reaction involved and the replacement strategy. b Western blotting using an anti-Flag antibody to detect the expressed proteins in extracts from adh1 mutant strains bearing the butanol production pathway with Bcd (B^R adh1Δ +5 g) or with Ter (B^R adh1Δ +5gT) relative to extracts from control strains bearing just Bcd (B^R + Bcd) or Ter (B^R + Ter). Protein products are labelled to the right and left of the gel image. A blot probed with an anti-eIF2α antibody provides a loading control (lower panel). c and d Graphs depicting the level of ethanol or butanol produced from adh1Δ mutant strains bearing five butanol production genes with either Bcd (B^R adh1Δ +5 g) or Ter (B^R adh1Δ +5gT) over a 21-day anaerobic fermentation. Error bars are ± SEM from five biological repeats