Schematic representation of Isobutyraldehyde production in E. coli. After glycolysis, two molecules of pyruvate are condensed into 2-acetolactate by acetolactate synthase (AlsS; B. subtilis), which is then converted into 2-ketoisovalerate (KIV) by acetohydroxy acid isomeroreductase and dihydroxy acid dehydratase (IlvC and ilvD; E. coli). Then, KIV is decarboxylated to form isobutyraldehyde by keto acid decarboxylase (Kivd; L. lactis). The target product, isobutyraldehyde, can be converted to the side product isobutanol by various aldehyde reductases (ALR) in E. coli.
Rodriguez and Atsumi Microbial Cell Factories 2012 11:90 doi:10.1186/1475-2859-11-90