Improving Free Fatty Acids Production by Combinatorial Metabolic Engineering

Microbial production of free fatty acids (FFAs) and their derivatives is considered a promising substitute for petroleum-based production to replace petroleum and petroleum production of chemicals. Thus, many studies have attempted to redesign microbes through metabolic engineering and synthetic biology for increased production of FFA. Here, we constructed a high FFA-producing Escherichia coli (E. coli) strain by combinatorial combinations of previous positive results; 1) overexpression of transcriptional activator (FadR) of fatty acid synthesis, 2) heterologous expression of the methylmalonyl-CoA carboxyltransferase (MMC) and overexpression of phosphoenolpyruvate carboxylase (PPC) to increase malonyl-CoA pool from oxaloacetate (OAA), 3) expressing a mutant acyl-CoA thioesterase I (???TesA) with high specific enzyme activity, and 4) deletion of FFA transport-related genes. The resulting strain improved FFA production up to 9.5-fold compared with the control strain expressing only the wild-type thioesterase