Fig. 4.

Improvements of isobutanol production by blocking competing pathways in S. cerevisiae. Fermentation experiments were performed aerobically at 30 °C in shake flasks in selective SCD medium without valine containing 40 g/L glucose. Pre-cultures carrying the episomal 2µ-plasmid IsoV100 were grown aerobically in fermentation medium, harvested at an OD₆₀₀ ≤ 3 and inoculated in fresh fermentation medium at a final OD₆₀₀ of 8. Fermentations were performed in duplicate per experiment and repeated at least twice. Error bars indicate standard deviation for experiments performed twice and standard error for experiments performed at least three times, respectively. a Glucose consumption after successively blocking of competing isobutanol pathways by deletion of key enzymes of biosynthesis pathways: CEN.PK113-7D (wt); JWY0 (∆ilv2); JWY01 (∆ilv2; Δbdh1; Δbdh2); JWY02 (∆ilv2; Δbdh1; Δbdh2; Δleu4; Δleu9); JWY03 (∆ilv2; Δbdh1; Δbdh2; Δleu4; Δleu9; Δecm31); JWY04 (∆ilv2; Δbdh1; Δbdh2; Δleu4; Δleu9; Δecm31; Δilv1); JWY12 (∆ilv2; Δbdh1; Δbdh2; Δleu4; Δleu9; Δecm31; Δilv1; Δpdc1::MTH1; Δpdc5); JWY13 (∆ilv2; Δbdh1; Δbdh2; Δleu4; Δleu9; Δecm31; Δilv1; Δpdc1; Δpdc5; Δmth1 (+ 169; + 393). b Isobutanol titer. c Isobutanol yield after 24 h