When they began this work, Lee and his colleagues did not know whether bisabolane could be used as a biofuel, but they targeted it on the basis of its chemical structure. Their first step was to perform fuel property tests on commercially available bisabolene, which comes as part of a mixture of compounds. Convinced they were onto something, the researchers then used biosynthesis to extract pure biosynthetic bisabolene from microbial cultures for hydrogenation into bisabolane. Subsequent fuel property tests on the bisabolane were again promising.
"Bisabolane has properties almost identical to D2 diesel but its branched and cyclic chemical structure gives it much lower freezing and cloud points, which should be advantageous for use as a fuel," Lee says. "Once we confirmed that bisabolane could be a good fuel, we designed a mevalonate pathway to produce the precursor, bisabolene. This was basically the same platform used to produce the anti-malarial drug artemisinin except that we introduced a terpene synthase and further engineered the pathway to improve the bisabolene yield both in E. coli and yeast."
Lee and his colleagues are now preparing to make gallons of bisabolane for tests in actual diesel engines, using the new fermentation facilities at Berkeley Lab's Advanced Biofuels Process Demonstration Unit. The ABPDU is a 15,000 square-foot state-of-the art facility, located in Emeryville, California, designed to help expedite the commercialization of advanced next-generation biofuels by providing industry-scale test beds for discoveries made in the laboratory.
"Once the complete fuel properties of hydrogenated biosyntheti
|Contact: Lynn Yarris|
DOE/Lawrence Berkeley National Laboratory