APPLICATIONS OF TECHNOLOGY:
Green source of
- Cosmetics, flavors, fragrances
- S. cerevisiae more genetically tractable than microalgae or oleaginous yeast
- Mutant strains easy to generate, isolate, analyze
- Proven track record of S. cerevisiae in industrial applications
- Readily scalable
- Controllable, economical fermentation technology
Joint BioEnergy Institute (JBEI) researchers led by Jay Keasling and Weerawat Runguphan have developed a method of genetically engineering budding yeast Saccharomyces cerevisiae (S. cerevisiae) to produce free fatty acids, fatty alcohols and biodiesels directly from simple sugars. As indicated in their Metabolic Engineering publication, the researchers demonstrated that S. cerevisiae provides a platform for a scalable route to key chemicals.
Rather than swap out individual fatty acid biosynthesis genes to enhance production, the Berkeley Lab team replaced the native promoters of all fatty acid biosynthesis genes with a strong constitutive promoter, yielding a strain that overproduces fatty acid. To augment triacylglycerol (TAG) accumulation, the researchers also overexpressed key fatty acid and TAG biosynthesis enzymes. Depending on the choice of converting enzyme, this engineered strain could produce and secrete directly into the culture medium fatty acid ethyl esters (biodiesel), free fatty acids, or fatty alcohols.
DEVELOPMENT STAGE: Bench-scale testing. The researchers overexpressed all three fatty acid biosynthesis genes – ACC1, FAS1, FAS2 – in S. cerevisiae. When coupled with TAG production, the engineered strain accumulated lipid to more than 17% its dry cell weight, a four-fold improvement over the control strain. Since TAG cannot be used directly as fuel, the researchers engineered S. cerevisiae to produce drop in fuels and chemicals. Altering the terminal converting enzyme in the engineered strain led to the production of free fatty acids at a titer of approx. 400 mg/L; fatty alcohols at approx. 100 mg/L; and fatty acid ethyl esters at approx. 5 mg/L directly from simple sugars.
STATUS: Patent pending. Available for licensing or collaborative research.
FOR MORE INFORMATION:
Runguphan, W. W., Keasling, J.D., “Metabolic engineering of Saccharomyces cerevisiae for production of fatty acid-derived biofuels and chemicals,” Metabolic Engineering, published online July 27, 2013.
REFERENCE NUMBER: 2013-113