• Number 349  |
• October 31, 2011

A Berkeley Lab biofuel that may be better than diesel

Bisabolane is an organic compound that has all the properties of D2 diesel fuel and then some: it has a much lower freezing point and is less likely to clog machinery at low temperatures. Now, by altering E. coli bacteria and Saccharomyces cerevisiae yeast, scientists in the Physical Sciences Division (PBD) of DOE’s Lawrence Berkeley National Laboratory and their colleagues in DOE’s Joint BioEnergy Institute (JBEI) have forged a path to replacing petroleum-derived diesel with a renewable biofuel, by coaxing these microbes to overproduce bisabolene, the precursor of bisabolane.

“This work is a proof of principle for advanced biofuels research,” says PBD’s Taek Soon Lee, who directs JBEI’s metabolic engineering program and is corresponding author of the paper in Nature Communications describing the research. “We’ve shown that we can design a biofuel target, evaluate this fuel target, and produce the fuel with microbes that we’ve engineered.”

Bisabolene is a sesquiterpene, among the terpenes produced by many plants, notably conifers; terpenes take their name from turpentine, made from pine resin. Sesquiterpenes have a high energy content and share many properties with diesel and jet fuels.

Says Lee, “Although plants are the natural source of terpene compounds, engineered microbial platforms would be the most convenient and cost-effective approach for large-scale production of advanced biofuels.”

Lee and his group earlier engineered a metabolic pathway important to biosynthesis in bacteria and yeast and, with the help of special enzymes, tweaked it to produce bisabolene. Initially they targeted bisabolene because of its chemical structure; only later did they learn of its remarkable potential for fuel production.

“Once we confirmed that bisabolane could be a good fuel, we designed a pathway to produce the precursor, bisabolene,” Lee says. The pathway they used was basically the same platform PBD’s Jay Keasling, JBEI CEO, pioneered to produce the antimalarial drug artemisinin.

At Berkeley Lab’s Advanced Biofuels Process Demonstration Unit, located near JBEI, Lee and his colleagues are now preparing to make bisabolane by the gallon, for tests in actual diesel engines.

[Lynn Yarris, 510.486.5375,
lcyarris@lbl.gov]