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 24, 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 24, 2014).

Share This




More Matter & Energy News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Creative Makeovers for Ugly Cellphone Towers

Creative Makeovers for Ugly Cellphone Towers

AP (July 24, 2014) Mobile phone companies and communities across the country are going to new lengths to disguise those unsightly cellphone towers. From a church bell tower to a flagpole, even a pencil, some towers are trying to make a point. (July 24) Video provided by AP
Powered by NewsLook.com
Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
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