Enhancing Microbial Pathways for Biofuel Production

The diverse array of structures within the terpene family is reflected by the variety of applications in society.

The Science

Produced in microbes and plants, terpenes are high-energy compounds that could be used for producing biofuels. For example, U.S. Department of Energy (DOE) researchers at the Joint BioEnergy Institute (JBEI) had reported that bisabolane, a biofuel derived from the sesquiterpene precursor bisabolene, could serve as an alternative to diesel fuel. Enhancing terpene yields in suitable microbes and plants is thus an important step toward commercial-scale production of these biofuels. Terpene synthesis in the majority of bacterial species, as well as in plant plastids, takes place via a pathway in which one-sixth of the carbon in the starting metabolites is lost as carbon dioxide (CO2). JBEI researchers wanted to improve terpene production in Escherichia coli by developing a pathway that would not result in any carbon loss as CO2. To do this, they focused on using a novel route that would form terpenes from 5-carbon (C5) sugars such as xylose, which is a breakdown product of hemicellulose. The researchers created a mutant in the metabolism of C5 sugars and then selected for complementary mutants that could grow on the C5 sugar xylose. E. coli colonies that were able to grow under this selective pressure were sequenced at DOE’s Joint Genome Institute and all were found to have mutations in the ribB gene. The researchers then inserted the pathway for bisabolene production into the strains able to grow on xylose, and they found bisabolene production in these strains. Further manipulation of the pathways by gene fusion and varying the gene order enhanced bisabolene yields several fold. These results demonstrate that biosynthetic pathways that are not found in nature may be constructed by selection and targeted engineering. This pathway is can now be further optimized for terpene yield in preparation for commercial-scale production.

Principal Investigator

Jay D. Keasling
Lawrence Berkley National Laboratory
[email protected]

BER Program Manager

Shing Kwok

U.S. Department of Energy, Biological and Environmental Research (SC-33)
Biological Systems Science Division
[email protected]


Kirby, J., M. Nishimoto, R. W. N. Chow, E. E. K. Baidoo, G. Wang, J. Martin, W. Schackwitz, R. Chan, J. L. Fortman, and J. D. Keasling. 2015. “Enhancing Terpene Yield from Sugars via Novel Routes to 1-Deoxy-d-Xylulose 5-Phosphate,” Applied and Environmental Microbiology 81,130–8. DOI: 10.1128/AEM.02920-14.