Multidimensional Metabolic Engineering and Fermentation Optimization for High-Level Production of Free Fatty Acids in Escherichia coli

Abstract

Free fatty acids (FFAs) can be readily converted to biofuels, such as alkane or fatty ethyl esters in the diesel range, by simple catalytic treatment. Therefore, microbial production of free fatty acid is expected to be an important share of fossil fuel alternatives. Many studies have been conducted to produce free fatty acid from cheap biomass such as glucose in Escherichia coli, which has made it possible to convert sustainable biomass into fuel. Fatty acid-based biofuels have been recently studied for further commercialization. Thus, various metabolic engineering efforts are being made to increase the titer, productivity, and yield of free fatty acid production in E. coli. There have been numerous single strategies aimed at increasing FFAs production, such as a heterologous expression or bypassing of acetyl-CoA carboxylase, introduction of mutant thioesterase I, disruption of membrane protein associated genes, and co-expression of regulatory transcription factor FadR. However, studies in which those strategies have been used in combination has not been yet reported. Here we report the combinational engineering and fermentation process optimization for high FFAs production in E. coli resulted in a 38-fold increase than the control strain.