Researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University and the Department of Systems Biology at Harvard Medical School have reported that they have engineered a line of the bacterium E. coli to mass-produce octanoate, a key precursor to developing biofuels with a high-octane content. The study was published in an online edition of Proceedings of the National Academy of Sciences on June 24 and signals a significant advancement in biofuel development.

The study was led by Pamela Silver, Ph.D., a Wyss Institute core faculty member, Professor of Systems Biology at Harvard Medical School, and senior author of the study. The lead coauthors of the study were Joe Torella, Ph.D. and Tyler Ford, both graduate students at the Harvard Medical School. Also on the team were Jeffrey Way, Ph.D., a senior staff scientist at Wyss Institute and Scott Kim and Amanda Chen, both students on Silver’s team.

Silver’s research team is interested in developing a biofuel that has a higher octane content than ethanol, the most common type of biofuel on the market. According to the Alternative Fuels Data Center, ethanol has a slightly lower energy content than gasoline. E10 (10% ethanol, 90% gasoline) has 96.7% of the energy content of gasoline, while E85 (85% ethanol, 15% gasoline) has 73%-83% of the energy content of gasoline.

Ethanol pump

Pictured above is a biofuel pump, with options for B20 (a 20% biodiesel blend), and two ethanol blends: E10 and E85. Credit: EERE.

The team hopes that their successful production of octanoate from E. coli will be just the first step in creating a high-octane biofuel with a similar energy content as gasoline. Next, the team will work on engineering E. coli to convert octanoate and additional fatty acids into alcohols. The alcohols can then be converted into octane.

Silver’s team was funded by the U. S. Department of Energy’s Advanced Research Project Agency-Energy (ARPA-E) and by the National Science Foundation. For the team’s published report, “Tailored Fatty Acid Synthesis via Dynamic Control of Fatty Acid Elongation,” please visit: http://www.pnas.org/content/early/2013/06/21/1307129110.




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