Featured Research

from universities, journals, and other organizations

Resistance is not futile: Researchers engineer resistance to ionic liquids in biofuel microbes

Date:
March 26, 2014
Source:
DOE/Lawrence Berkeley National Laboratory
Summary:
Researchers have identified the genetic origins of a microbial resistance to ionic liquids and successfully introduced this resistance into a strain of E. coli bacteria for the production of advanced biofuels.

JBEI researchers identified the genetic origins of a resistance to ionic liquids found in Enterobacter lignolyticus, a soil bacterium discovered in a rainforest in Puerto Rico.
Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory

Researchers with the U.S. Department of Energy (DOE)'s Joint BioEnergy Institute (JBEI), a multi-institutional partnership led by Berkeley Lab, have identified the genetic origins of a microbial resistance to ionic liquids and successfully introduced this resistance into astrain of E. coli bacteria for the production of advanced biofuels. The ionic liquid resistance is based on a pair of genes discovered in a bacterium native to a tropical rainforest in Puerto Rico.

"We identified two genes in Enterobacter lignolyticus, a soil bacterium that is tolerant to imidazolium-based ionic liquids, and transferred them as part of a genetic module into an E.coli biofuel host," says Michael Thelen, a biochemist with JBEI's Deconstruction Division. "The genetic module conferred the tolerance needed for the E.coli to grow well in the presence of toxic concentrations of ionic liquids. As a result, production of a terpene-based biofuel was enhanced."

Thelen, a senior investigator with DOE's Lawrence Livermore National Laboratory (LLNL), is the corresponding author of a paper describing this work in Nature Communications. The paper is titled "An auto-inducible mechanism for ionic liquid resistance in microbial biofuel production." Thomas Ruegg, a Ph.D. student from Basel University associated with LLNL, is the lead author. Co-authors are Eun-Mi Kim, Blake Simmons, Jay Keasling, Steven Singer and Taek Soon Lee.

The burning of fossil fuels continues to release nearly 9 billion metric tons of excess carbon into the atmosphere each year to the detriment of global climate trends. Advanced biofuels synthesized from the cellulosic biomass in non-food plants represent a clean, green, renewable alternative to today's gasoline, diesel and jet fuels.

JBEI researchers have previously engineered strains of E. coli bacteria to digest the cellulosic biomass of switchgrass, a perennial grass that thrives on land not suitable for food crops, and convert its sugars into biofuels and chemicals. However, the ionic liquids used to make the switchgrass digestible for the E.coli was also toxic to them and had to be completely removed through several washings prior to fermentation.

"The extensive washing required for complete ionic liquid removal is not feasible in large-scale, industrial applications," says Blake Simmons, a chemical engineer who heads JBEI's Deconstruction Division. "An ideal and more sustainable process is to balance the costs of removing the ionic liquid with the fermentation performance by using biofuel-producing microbes that can tolerate residual levels of ionic liquids."

Two years ago, JBEI researchers returned from an expedition to the El Yunque National Forest in Puerto Rico with the SCF1 strain of Enterobacter lignolyticus, which had shown a tolerance to high osmotic pressures of the sort generated by exposure to ionic liquids. A model was developed at JBEI in which the SCF1 bacteria are able to resist the toxic effect of an ionic liquid by altering the permeability of their cell membrane and pumping the toxic chemical out of the cell before damage occurs.

In this latest study, the JBEI researchers used a creative approach devised by lead author Ruegg to rapidly pinpoint the genes responsible for ionic liquid resistance in the genomic DNA of SCF1.

"This genetic module encodes both a membrane transporter and its transcriptional regulator," Ruegg says. "While the pump exports ionic liquids, the substrate-inducible regulator maintains the appropriate level of this pump so that the microbe can grow normally either in the presence or absence of ionic liquid."

The results of this study show a way to eliminate a bottleneck in JBEI's biofuels production strategy, which relies on ionic liquid pretreatment of cellulosic biomass. It also shows how the adverse effects of ionic liquids can be turned into an advantage.

"The presence of residual ionic liquids may prevent the growth of microbial contaminants, so that fermentation can proceed under more economical, aseptic conditions," Thelen says. "Our findings should pave the way for further improvements in microbes that will contribute to the sustainable production of biofuels and chemicals."

This research was funded by 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. Thomas L. Ruegg, Eun-Mi Kim, Blake A. Simmons, Jay D. Keasling, Steven W. Singer, Taek Soon Lee, Michael P. Thelen. An auto-inducible mechanism for ionic liquid resistance in microbial biofuel production. Nature Communications, 2014; 5 DOI: 10.1038/ncomms4490

Cite This Page:

DOE/Lawrence Berkeley National Laboratory. "Resistance is not futile: Researchers engineer resistance to ionic liquids in biofuel microbes." ScienceDaily. ScienceDaily, 26 March 2014. <www.sciencedaily.com/releases/2014/03/140326142214.htm>.
DOE/Lawrence Berkeley National Laboratory. (2014, March 26). Resistance is not futile: Researchers engineer resistance to ionic liquids in biofuel microbes. ScienceDaily. Retrieved July 28, 2014 from www.sciencedaily.com/releases/2014/03/140326142214.htm
DOE/Lawrence Berkeley National Laboratory. "Resistance is not futile: Researchers engineer resistance to ionic liquids in biofuel microbes." ScienceDaily. www.sciencedaily.com/releases/2014/03/140326142214.htm (accessed July 28, 2014).

Share This




More Matter & Energy News

Monday, July 28, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

The Carbon Trap: US Exports Global Warming

The Carbon Trap: US Exports Global Warming

AP (July 28, 2014) AP Investigation: As the Obama administration weans the country off dirty fuels, energy companies are ramping-up overseas coal exports at a heavy price. (July 28) Video provided by AP
Powered by NewsLook.com
Shipping Crates Get New 'lease' On Life

Shipping Crates Get New 'lease' On Life

Reuters - Business Video Online (July 25, 2014) Shipping containers have been piling up as America imports more than it exports. Some university students in Washington D.C. are set to get a first-hand lesson in recycling. Their housing is being built using refashioned shipping containers. Lily Jamali reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Highest Train Turns 80 in French Pyrenees

Europe's Highest Train Turns 80 in French Pyrenees

AFP (July 25, 2014) Europe's highest train, the little train of Artouste in the French Pyrenees, celebrates its 80th birthday. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
TSA Administrator on Politics and Flight Bans

TSA Administrator on Politics and Flight Bans

AP (July 24, 2014) TSA administrator, John Pistole's took part in the Aspen Security Forum 2014, where he answered questions on lifting of the ban on flights into Israel's Tel Aviv airport and whether politics played a role in lifting the ban. (July 24) 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:
from the past week

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