Metabolic design of a platform Escherichia coli strain producing various chorismate derivatives

• A novel metabolic pathway was designed to overproduce aromatic compounds in E. coli.
• The yield of salicylate in test tube culture was improved (6.2-fold higher).
• 11.5 g/L of salicylate was produced, corresponding to a yield from glucose of 40%.
• The salicylate-overproducing E. coli produced only a small amount of organic acids.
• A platform strain capable of producing various chorismate derivatives was created.

A synthetic metabolic pathway suitable for the production of chorismate derivatives was designed in Escherichia coli. An L-phenylalanine-overproducing E. coli strain was engineered to enhance the availability of phosphoenolpyruvate (PEP), which is a key precursor in the biosynthesis of aromatic compounds in microbes. Two major reactions converting PEP to pyruvate were inactivated. Using this modified E.coli as a base strain, we tested our system by carrying out the production of salicylate, a high-demand aromatic chemical. The titer of salicylate reached 11.5 g/L in batch culture after 48 h cultivation in a 2-liter jar fermentor, and the yield from glucose as the sole carbon source exceeded 40% (mol/mol). In this test case, we found that pyruvate was synthesized primarily via salicylate formation and the reaction converting oxaloacetate to pyruvate. In order to demonstrate the generality of our designed strain, we employed this platform for the production of each of 7 different chorismate derivatives. Each of these industrially important chemicals was successfully produced to levels of 1–3 g/L in test tube-scale culture.