The field of metabolic engineering has equipped scientists with the ability to harness the power of biology to produce a wide variety of difficult to synthesize plant natural products at high titers, yields, and productivities. The high-titer microbial synthesis of these compounds is possible through the careful optimization of both internal genetic elements and external fermentation conditions. Although, recent advances have shown highly efficient production to be possible, many systems still result in non-industrially feasible titers. This less than desirable production is, in part, due to the high metabolic burden of expressing extensive extrinsic pathways in a single microbial strain. This work attempts to reduce the metabolic stresses associated with expressing a 6-gene flavonoid pathway by separating the burden of enzyme over-expression across two E. coli strains in co-culture. Using this method, we demonstrate a 970-fold improvement in the titer of green tea catechins over previous literature reports. To accomplish this task, careful experimental optimization of carbon source, induction temperature, induction point, inoculation ratio, and strain choice was used to map the production landscape. Additionally, empirical modelling techniques were applied to predict conditions for optimal production. Searching the solution space surrounding the predicted optimum resulted in a 62% improvement in afzelechin titer to 40.7±0.1 mg/L from p-coumaric acid. Poly-cultures, or the use of three or more strains in co-culture, will also be discussed as a technique to further extend the flavonoid branch pathway in E. coli. These results highlight the potential for the use of co-culture methods to further improve microbial production of plant natural products in E. coli.

Optimization of E. coli co-cultures for the high-yield production of plant polyphenols

251st National Meeting (2016)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.