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DOE Pulse
  • Number 412  |
  • April 28, 2014

LLNL scientists discover bacterial resistance to improve biofuel production

Ionic liquids (molten salts) are important solvents in the microbial production of biofuels, but can inhibit microbial growth. Lawrence Livermore researchers discovered a resistance mechanism in a rainforest soil bacterium that enables E. coli to grow and produce biofuel in the presence of ionic liquids at levels that otherwise would be toxic to native strains.

Ionic liquids (molten salts) are important
solvents in the microbial production of
biofuels, but can inhibit microbial growth.
Lawrence Livermore researchers discovered
a resistance mechanism in a rainforest soil
bacterium that enables E. coli to grow and
produce biofuel in the presence of ionic
liquids at levels that otherwise would be
toxic to native strains.

Scientists from DOE's Lawrence Livermore National Laboratory (LLNL) in conjunction with the Joint BioEnergy Institute (JBEI) have discovered that a type of bacterial resistance may provide more efficient production of biofuels.

The team identified the genetic origin of bacterial resistance to an ionic liquid (a salt in the liquid state), which they successfully introduced into a strain of E. coli bacteria for advanced biofuels production. The ionic liquid resistance is based on a pair of genes discovered in a microbial species native to a tropical rainforest in Puerto Rico.

The team identified two genes in a rainforest soil bacterium that’s tolerant to specific ionic liquids, and transferred them as part of a genetic module into an E. coli biofuel host.

"Ionic liquids are used as potent solvents to extract cellulose from biomass, so that it can be broken down to sugars used by microbes to make advanced biofuels -- new liquid fuels that go beyond ethanol and can replace gasoline or diesel," said Michael Thelen, an LLNL biochemist who also is part of 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.

The research appears in the March 26 edition of the journal, Nature Communications: http://www.nature.com/ncomms/index.html.

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[Anne Stark, 925.422.9799,
stark8@llnl.gov]