Metabolic engineering of Saccharomyces cerevisiae for the production of sesquiterpenes

Terpenes are a broad class of molecules including many high value, commercially relevant species. Until recently, these chemicals were only available as extracts from plants as they are complex molecules and difficult to synthesize by traditional means. Through the use of metabolic engineering of industrial microbes, new routes were paved to synthesize these plant-derived molecules. Not only are these new routes more cost-effective, but they are also renewable, sustainable and are not threatened by changing climate conditions or crop disease.

Evolva is interested in the production of several important molecules from the terpene family; however, this presentation is focused on the production of the sesquiterpenes, valencene and its oxidized form, nootkatone. Valencene and nootkatone are both important molecules in the flavor and fragrance industry and nootkatone has also shown promise in the insect control market as a repellant against ticks, mosquitos and others.

For the production of sesquiterpenes, like valencene and nootkatone, in S. cerevisiae, a common precursor is utilized. Farnesyl pyrophosphate (FPP) is produced in S. cerevisiae through the mevalonate pathway and serves as the lead-off point for downstream engineering. Following the production of FPP, a cyclization reaction catalyzed by a plant-derived valencene synthase enzyme converts FPP to valencene. Valencene is then converted to nootkatone by either chemical or biosynthetic oxidation utilizing a combination of p450 oxidases and reductases, p450 oxidoreductases, other oxidases and dehydrogenases. Optimization of these metabolic reactions in S. cerevisiae along with strategies for creating a robust and stable industrial strain will be discussed.