Retooling Glycolysis in Saccharomyces Cerevisiae for More Efficient Isoprenoid Production

Microbially derived complex anabolic compounds such as isoprenoids have previously been confined to applications in the pharmaceutical or specialty chemical industries, in part because the energetic costs of biosynthesis translate to high production costs.  Here, we design and construct an alternative carbon metabolism in Saccharomyces cerevisiae which reduces the metabolic cost of converting glucose to farnesyl pyrophosphate (FPP), the universal precursor for all sesquiterpene isoprenoids. By partitioning glucose dissimilation between parallel heterologous routes and by altering the cofactor requirements of FPP biosynthesis, we dramatically improve internal pathway balance, reducing reliance upon CO₂-emitting and oxygen-consuming side-reactions to maintain redox homeostasis and energy charge. The result is a 20% relative improvement in the theoretical yield of farnesene from glucose (g/g), and a 170% relative improvement in the theoretical yield of farnesene from oxygen (mol/mol). We transplant the synthetic metabolic network into a strain of S. cerevisiae that was previously engineered for commercial-scale production of farnesene, a commercially important molecule whose derivatives can be used in a wide variety of applications ranging from fuels to novel performance materials. In this strain background, we observe an 80% relative increase in the molar yield of farnesene from oxygen, which translates to a proportional increase in farnesene productivity in commercial fermentation conditions.  This improvement in productivity enables microbial production of an anabolic secondary metabolite at a scale previously accessible only to catabolites and primary metabolites.