Engineering Clostridial Aldehyde/Alcohol Dehydrogenase for Selective Butanol Production.

Butanol production by is accompanied by coproduction of acetone and ethanol, which reduces the yield of butanol and increases the production cost. Here, we report development of several clostridial aldehyde/alcohol dehydrogenase (AAD) variants showing increased butanol selectivity by a series of design and analysis procedures, including random mutagenesis, substrate specificity feature analysis, and structure-based butanol selectivity design. The butanol/ethanol ratios (B/E ratios) were dramatically increased to 17.

One hundred years of clostridial butanol fermentation.

Butanol has been widely used as an important industrial solvent and feedstock for chemical production. Also, its superior fuel properties compared with ethanol make butanol a good substitute for gasoline. Butanol can be efficiently produced by the genus Clostridium through the acetone-butanol-ethanol (ABE) fermentation, one of the oldest industrial fermentation processes.