Modular optimization of multi-gene pathways for fatty acids production in E. coli

Microbial fatty acid-derived fuels have emerged as promising alternatives to petroleum-based transportation fuels. Here we report a modular engineering approach that systematically removed metabolic pathway bottlenecks and led to significant titre improvements in a multi-gene fatty acid metabolic pathway. On the basis of central pathway architecture, E. coli fatty acid biosynthesis was re-cast into three modules: the upstream acetyl coenzyme A formation module; the intermediary acetyl-CoA activation module; and the downstream fatty acid synthase module. Combinatorial optimization of transcriptional levels of these three modules led to the identification of conditions that balance the supply of acetyl-CoA and consumption of malonyl-CoA/ACP. Refining protein translation efficiency by customizing ribosome binding sites for both the upstream acetyl coenzyme A formation and fatty acid synthase modules enabled further production improvement. Fed-batch cultivation of the engineered strain resulted in a final fatty acid production of 8.6 g l −1 . The modular engineering strategies demonstrate a generalized approach to engineering cell factories for valuable metabolites production. Microbial fatty acid-derived fuels represent promising alternatives to the traditionally used fossil fuels. Koffas and colleagues report that E. coli central metabolism can be modified to produce large quantities of fatty acids through a modular pathway engineering strategy.