Medium-Chain Carboxylic Acid and Alcohol Production Via Engineered β-Oxidation in E. coli

Rising fossil fuel prices along with environmental concerns associated to their use have stimulated the development of alternative methods for fuel and chemical production from renewable resources. Previous studies have demonstrated the feasibility of producing aliphatic hydrocarbons derived from fatty acid biosynthesis in Escherichia coli. In this work, we present new methods to produce saturated and unsaturated carboxylic acids and alcohols using an engineered b-oxidation reversal. To increase the availability of acyl-CoAs for product synthesis, we deleted known endogenous thioesterases. Chromosomal over-expression of key core b-oxidation reversal and termination enzymes in this thiosterase-deficient strain led to saturated and unsaturated carboxylic acid production at titers reaching 0.5 g/L and 0.8 g/L, respectively. By combining the engineered b-oxidation reversal with appropriate acyl-CoA reductases, we achieved the direct production of medium-chain (C6-C10) alcohols from glycerol.