Featured Research

from universities, journals, and other organizations

Fragrant new biofuel: Researchers develop a new candidate for a cleaner, greener and renewable diesel fuel

Date:
March 14, 2012
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
Researchers have identified methyl ketones, chemical compounds known for their fragrance and flavor, as strong biofuel candidates. Methyl ketones produced from glucose by engineered E. coli yielded high cetane numbers -- a diesel fuel rating comparable to the octane number for gasoline.

Harry Beller (foreground) and Ee-Been Goh of the Joint BioEnergy Institute have identified microbial-produced methyl ketones as strong biofuel candidates.
Credit: Photo by Roy Kaltschmidt, Berkeley Lab

A class of chemical compounds best known today for fragrance and flavor may one day provide the clean, green and renewable fuel with which truck and auto drivers fill their tanks. Researchers at the U.S. Department of Energy's Joint BioEnergy Institute (JBEI) have engineered Escherichia coli (E. coli) bacteria to generate significant quantities of methyl ketone compounds from glucose. In subsequent tests, these methyl ketones yielded high cetane numbers -- a diesel fuel rating comparable to the octane number for gasoline -- making them strong candidates for the production of advanced biofuels.

Related Articles


"Our findings add to the list of naturally occurring chemical compounds that could serve as biofuels, which means more flexibility and options for the biofuels industry," says Harry Beller, a JBEI microbiologist who led this study. "We're especially encouraged by our finding that it is possible to increase the methyl ketone titer production of E. coli more than 4,000-fold with a relatively small number of genetic modifications."

Beller directs the Biofuels Pathways department for JBEI's Fuels Synthesis Division, and also is a senior scientist with the Earth Sciences Division of Lawrence Berkeley National Laboratory (Berkeley Lab). He is the corresponding author of a paper describing this work titled "Engineering of Bacterial Methyl Ketone Synthesis for Biofuels," which was published in the journal Applied and Environmental Microbiology. Co-authoring this paper were Ee-Been Goh, who is the first author on the paper, plus Edward Baidoo and Jay Keasling.

Advanced biofuels -- liquid transportation fuels derived from the cellulosic biomass of perennial grasses and other non-food plants, as well as from agricultural waste -- are highly touted as potential replacements for gasoline, diesel and jet fuels. Equally touted is the synthesis of these fuels through microbes that digest the biomass and convert its sugars into fuel molecules. At JBEI, researchers are focusing on developing advanced biofuels that can be used in today's engines and distribution infrastructures. In previous research, Beller and his colleagues engineered E. coli with special enzymes to synthesize from fatty acids long-chain alkene hydrocarbons that can be turned into diesel fuel. Fatty acids are the energy-rich molecules in bacterial and plant cells that have been dubbed nature's petroleum.

"In those studies, we noticed that bacteria engineered to produce unnaturally high levels of fatty acids also produced some methyl ketones," Beller says. "When we tested the cetane numbers of these ketones and saw that they were quite favorable, we were prompted to look more closely at developing methyl ketones as biofuels."

Methyl ketones are naturally occurring compounds discovered more than a century ago in the aromatic evergreen plant known as rue. Since then they've been found to be common in tomatoes and other plants, as well as insects and microorganisms. Today they are used to provide scents in essential oils and flavoring in cheese and other dairy products. Although native E. coli make virtually undetectable quantities of methyl ketones, Beller and his colleagues were able to overcome this deficiency using the same tools of synthetic biology they used to engineer high fatty acid-producing E.coli.

"For methyl ketone production, we made two major modifications to E. coli," Beller says. "First we modified specific steps in beta-oxidation, the metabolic pathway that E. coli uses to break down fatty acids, and then we increased the expression of a native E. coli protein called FadM. These two modifications combined to greatly enhance the production of methyl ketones."

Beller and his colleagues tested two methyl ketones for cetane numbers -- undecanone and tridecanone. The cetane number is a measure of ignition delay during compression ignition; a higher number indicates a shorter ignition delay period and is more favorable than a lower number. In the United States, diesel fuel must have a minimum cetane number of 40. The cetane number for undecanone was 56.6. The number for a 50/50 mix of undecanone and tridecanone was 58.4 Despite this impressive performance, there was a concern that both these methyl ketones have a relatively high melting point, which is a disadvantage for cold-temperature fuel properties.

"We were able to mitigate the melting point problem in our best producing strains of E.coli by increasing the percentage of monounsaturated methyl ketones, which have much lower melting points than their saturated homologs," Beller says.

For the next step, Beller and his colleagues will focus on increasing production and optimizing fuel properties of the methyl ketones by modulating their composition with respect to chain length and degree of unsaturation.

"Since these methyl ketones are fatty acid-derived compounds, we hope that advances that we make in enhancing their microbial production will have relevance to other fatty acid-derived biofuels as well," Beller says.

This research was supported by JBEI through the DOE Office of Science.


Story Source:

The above story is based on materials provided by DOE/Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. E.-B. Goh, E. E. K. Baidoo, J. D. Keasling, H. R. Beller. Engineering of Bacterial Methyl Ketone Synthesis for Biofuels. Applied and Environmental Microbiology, 2011; 78 (1): 70 DOI: 10.1128/AEM.06785-11

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Fragrant new biofuel: Researchers develop a new candidate for a cleaner, greener and renewable diesel fuel." ScienceDaily. ScienceDaily, 14 March 2012. <www.sciencedaily.com/releases/2012/03/120314101245.htm>.
DOE/Lawrence Berkeley National Laboratory. (2012, March 14). Fragrant new biofuel: Researchers develop a new candidate for a cleaner, greener and renewable diesel fuel. ScienceDaily. Retrieved December 22, 2014 from www.sciencedaily.com/releases/2012/03/120314101245.htm
DOE/Lawrence Berkeley National Laboratory. "Fragrant new biofuel: Researchers develop a new candidate for a cleaner, greener and renewable diesel fuel." ScienceDaily. www.sciencedaily.com/releases/2012/03/120314101245.htm (accessed December 22, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Monday, December 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava Inches Closer to Highway

Raw: Lava Inches Closer to Highway

AP (Dec. 21, 2014) Officials have opened a new road on Hawaii's Big Island for drivers to take care of their daily needs if encroaching lava from Kilauea Volcano crosses a highway and cuts them off from the rest of the island. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Raw: Scuba Diving Santa Off Florida Keys

Raw: Scuba Diving Santa Off Florida Keys

AP (Dec. 20, 2014) A scuba diving Santa Claus explored the waters of the Florida Keys National Marine Sanctuary. Dive shop owner Spencer Slate makes the dive each year to help raise money for charity. (Dec. 20) Video provided by AP
Powered by NewsLook.com
Obama: Better Ways to Create Jobs Than Keystone Pipeline

Obama: Better Ways to Create Jobs Than Keystone Pipeline

AFP (Dec. 19, 2014) US President Barack Obama says that construction of the Keystone pipeline would have 'very little impact' on US gas prices and believes there are 'more direct ways' to create construction jobs. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com
Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins