Metabolic Engineering of Saccharomyces Cerevisiae for Production of Alkanes from Free Fatty Acids

In view of concerns regarding depletion of petroleum resources and environmental issues arising from heavy reliance on fossil fuel for energy, much attention has been paid to developing microbial biosynthesis of biofuels for generating sustainable and renewable energy sources. Alkane is an ideal biofuel candidate because it is a major component of fossil fuel and is high in energy density. Although production of alkane in bacterial hosts has been extensively explored in the past few years, research on alkane biosynthesis in yeast lags far behind. Despite Saccharomyces cerevisiae being a robust industrial production host, biosynthesis of alkane from fatty acyl-CoA in S. cerevisiae was reported only recently. However, the yield was limited partly by low production of the aldehyde intermediate. Here, we report the engineering of S. cerevisiae for improved production of aldehyde from free fatty acid source for alkane biosynthesis.

Oxidoreductases that convert fatty acids to aldehydes are present in plants for signaling against biotic and abiotic stresses. We functionally expressed a plant oxidoreductase heterologously in S. cerevisiae to produce aldehydes from free fatty acids in vivo. Co-expression of aldehyde decarbonylases effected production of alkanes. The heterologous alkane production pathway was further optimized by gene deletions to increase the availability of free fatty acids to serve as substrate and selecting appropriate promoters for gene expression to improve metabolic flux. The engineered S. cerevisiae described here is a highly promising platform for alkane production from free fatty acids and the findings in this work will facilitate future development of alkane-producing yeast hosts.