Engineering E.coli Fatty Acid Synthesis for the Production of Biofuel Precursors

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Tyler Ford, Joseph Torella, Jeffrey Way, Pamela Silver

Harvard University, United States

Fatty acids are highly reduced, energy rich compounds that are potential precursors to biofuels and other commodities. E.coli produce an abundance of fatty acids as a major component of their lipid membranes and much work has been done to increase E.coli production of these long chain fatty acids. In this work, we engineer E.coli to selectively produce medium chain fatty acids, which are potentially more valuable biofuel precursors than long chain fatty acids. To this end, we use traditional metabolic engineering techniques including gene knockouts and over-expression, but also replace an endogenous fatty acid synthesis enzyme with one designed to produce eight carbon fatty acids. Finally, we make use of a previously engineered ClpXP inducible degradation system to degrade a second, essential, fatty acid synthesis enzyme that pulls carbon flux away from medium chain fatty acid production. Using these techniques, we show that we can produce medium chain fatty acids at greater than 12% theoretical yield in E.coli. We are currently using this same inducible degradation system to degrade other essential metabolic enzymes in E.coli and thereby dynamically redirect metabolic flux. We predict that these techniques can be used to increase the biological production of a variety of commercially desirable compounds.