Although microorganisms can be engineered to convert renewable biomass into an array of useful chemicals, the same products often inhibit the productivity of the producing microbes. This project seeks to explore strategies for engineering more tolerant microbes in support of enhanced chemical production. Novel enzyme pathways will first be engineered to enable the individual biosynthesis of four aromatic products that are currently derived from petroleum. Their alternative bioproduction will ultimately help to reduce U.S. dependence on foreign oil and gas. The materials and strategies developed in this project will ultimately benefit not only the production of renewable aromatic chemicals, but also a broad range of other useful bioproducts, including biofuels.

In addition to expanding the number and diversity of conventional petrochemical replacements that can be synthesized microbially through the creation of enzyme pathways, this project further seeks to explore strategies for engineering more tolerant microbes in support of enhanced chemical production. Novel enzyme pathways will first be engineered to enable the individual biosynthesis of four aromatic products: styrene, (S)-styrene oxide, (R)-styrene glycol, and 2-phenylethanol. To counter the inhibitory effects associated with microbial chemical production, strategies will be explored to improve tolerance and productivity by actively excreting toxic products from cells as they are synthesized. This will be achieved with the aid of both native and heterologous efflux transporter proteins. Finally, novel gene circuits will be engineered to control the expression of efflux pumps only if and when needed by the cell, thereby allowing cells to conserve valuable resources for further chemical production. The development of novel, aromatic-inducible gene circuits to control transporter expression will demonstrate how self-actuating control strategies can be used to maintain maximal host fitness by affording cells the ability to sense and respond to dynamic changes in their environment and intrinsic metabolism. The close integration of the research with educational and outreach activities will be a key component of this project.

This award by the Biotechnology and Biochemical Engineering Program of the CBET Division is co-funded by the Systems and Synthetic Biology Program of the Division of Molecular and Cellular Biology.