Fig. 1

Simplified metabolic network of Escherichia coli for substrate uptake, mixed acid fermentation pathways and 2,3-butanediol production. Green arrows/genes represent the introduced heterologous 2,3-butanediol pathway. Red crosses/genes indicate genes knocked-out in E. coli ∆ldhA ∆adhE ∆pta ∆frdA/445_Ediss (445_Ediss ∆4) and the purple cross/gene indicates the additional knock-out in E. coli ∆ldhA ∆adhE ∆pta ∆frdA ∆pykA/445_Ediss (445_Ediss ∆5)