P84: Overcoming Bottlenecks to Fatty Acid Overproduction in E. coli 

Free fatty acids are a desirable intermediate for a wide range of chemical and biological conversions to high energy density liquid transportation fuels such as alkanes and alkyl esters.  A strain of Escherichia coli was metabolically engineered that overproduces fatty acids in Luria-Bertani medium supplemented with glycerol, with a composition of predominantly medium chain length (C₁₂) species.  Due to the need to utilize lignocellulosic feedstocks as a carbon source, overproduction of free fatty acids has also been demonstrated when engineered strains are grown directly in pretreated biomass.  A common theme in all investigated growth conditions is a lack of ability of the cultures to consume all of the supplied carbon before losing viability, resulting in fatty acid yields significantly below the maximum theoretical yield.   To further elucidate the strain physiology and to identify additional genetic modifications that improve production, a multiomics study has been undertaken involving gene expression profiling with DNA microarrays, proteomic analysis, and metabolite profiling.  The results of this comprehensive analysis will be presented and further experiments based upon these findings will be discussed.