Biological production of platform chemicals from renewable sources has recently attracted attention as an alternative to petro-based production, owing to increasing concerns about depletion of fossil resources and other environmental issues. 1-Butanol is an important C4 chemical feedstock, used not only as the starting material for production of industrial chemicals, including latex surface coatings, enamels, and lacquers, but also as a solvent for synthesizing antibiotics, vitamins, and hormones. Recently, 1-butanol has come under the global spotlight as a new-generation biofuel, and it is favored over ethanol for its excellent fuel properties. Compared with ethanol, 1-butanol contains 25% more energy