An Integrated Computational and Experimental Study to Increase the Production Rate of Flavanones in Escherichia Coli

Many plant-specific chemical compounds such as flavanones are important drug and pharmaceutical precursors. Bottlenecks in genetically engineering plant species and lower synthesis rates have motivated efforts to design recombinant strains of popular production hosts (e.g. Escherichia coli and yeast) to produce flavanones. Genes responsible for the synthesis of flavanones, 4-coumaroyl-CoA ligase (4CL), chalcone synthase (CHS) and chalcone isomerase (CHI), have been successfully cloned and expressed in E. coli and Saccharomyces cerevisiae using expression plasmids. Furthermore, metabolic engineering strategies to boost the production of malonyl-CoA, an important precursor, have resulted in significantly improved yields.

In this talk, we present milestones reached when computationally derived predictions using the OptForce procedure for increasing the yield of flavanones in E. coli are implemented and experimentally tested. OptForce identified four new knockouts and overexpressions that increase the availability of important precursors for flavanone synthesis in the wild-type strain of E. coli (BL21*) growing under aerobic conditions with glucose as the substrate and phenylpropanoic acid as a supplement to the flavanone pathway. Experimental results revealed a three-fold increase in the yield of flavanones. In addition, the recombinant strains exhibited stable growth characteristics as predicted by OptForce and at the same time producing flavanones in high concentrations during a 30-hour batch fermentation process.