Engineering Clostridial Aldehyde/Alcohol Dehydrogenase for Selective Butanol Production

Abstract

Renewable biofuel represents one of the answers to solving the energy crisis and climate change problems. Butanol produced naturally by clostridia has superior liquid fuel characteristics and thus has the potential to replace gasoline. Due to the lack of efficient genetic manipulation tools, however, clostridial strain improvement has been slower than improvement of other microorganisms. Furthermore, fermentation coproducing various by-products requires costly downstream processing for butanol purification. Here, we report the results of enzyme engineering of aldehyde/alcohol dehydrogenase (AAD) to increase butanol selectivity. A metabolically engineered Clostridium acetobutylicum strain expressing the engineered aldehyde/alcohol dehydrogenase gene was capable of producing butanol at a high level of selectivity.