Quantitative analysis and engineering of fatty acid biosynthesis in E. coli

Fatty acids are central hydrocarbon intermediates in the biosynthesis of diesel from renewable sources. We have engineered an Escherichia coli cell line that produces 4.5 g/L/day total fatty acid in a fed-batch fermentation. However, further enhancement of fatty acid biosynthesis in this cell line proved unpredictable. To develop a more reliable engineering strategy, a cell-free system was developed that enabled direct, quantitative investigation of fatty acid biosynthesis and its regulation in E. coli. Using this system, the strong dependence of fatty acid synthesis on malonyl-CoA availability and several important phenomena in fatty acid synthesis were verified. Results from this cell-free system were confirmed via the generation and analysis of metabolically engineered strains of E. coli. Our quantitative findings highlight the enormous catalytic potential of the E. coli fatty acid biosynthetic pathway, and target specific steps for protein and metabolic engineering to enhance the catalytic conversion of glucose into biodiesel.