Development of an orthogonal fatty acid biosynthesis system in E. coli for oleochemical production.

Here we report recombinant expression and activity of several type I fatty acid synthases that can function in parallel with the native Escherichia coli fatty acid synthase. Corynebacterium glutamicum FAS1A was the most active in E. coli and this fatty acid synthase was leveraged to produce oleochemicals including fatty alcohols and methyl ketones. Coexpression of FAS1A with the ACP/CoA-reductase Maqu2220 from Marinobacter aquaeolei shifted the chain length distribution of fatty alcohols produced. Coexpression of FAS1A with FadM, FadB, and an acyl-CoA-oxidase from Micrococcus luteus resulted in the production of methyl ketones, although at a lower level than cells using the native FAS. This work, to our knowledge, is the first example of in vivo function of a heterologous fatty acid synthase in E. coli. Using FAS1 enzymes for oleochemical production have several potential advantages, and further optimization of this system could lead to strains with more efficient conversion to desired products. Finally, functional expression of these large enzyme complexes in E. coli will enable their study without culturing the native organisms.