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Halophilic and Thermostable Cellulases Tolerant to Ionic Liquids




Researchers from the DOE Joint Genome Institute (JGI) and the Joint BioEnergy Institute (JBEI) have developed a salt-tolerant (halophilic) enzyme to hydrolyze cellulosic biomass in the presence of ionic liquids, an energy-saving, environmentally friendly pretreatment method. The enzyme can also be used in dilute acid/base pretreatment processes in which high salt accumulates as the pH of the solution neutralizes.

The JBEI cellulase, Hu-CBH1, is resistant to up to 20% ionic liquid in solution, a capability that reduces the number of washes required following pretreatment and increases the monomeric sugar yield. Specifically, the enzyme has significant cellobiohydrolase (CBH) activity and stability in high salt buffer (5M NaCl) and high temperature (80˚C).

The JBEI researchers used sequence analysis to overcome past barriers to growing halophiles in a laboratory setting and derive Hu-CBH1 from halophilic archaea. This invention also includes a strategy to screen halophilic enzymes for IL-resistant enzymes.

Because Hu-CBH1 is alkaliphilic as well, it can be used in the paper, detergent and textile industries for bioremediation of cellulosic contaminants in high salt environments. The enzyme may advance the use of seawater, an inexpensive and unlimited resource, for the water-intensive process of biomass conversation, a process not previously possible due to the lack of salt tolerant enzymes for biomass hydrolysis.

Neither bacterial nor fungal cellulases can tolerate high ionic liquid and/or salt concentrations and therefore require extensive washing of the recovered product before saccharification, which increases overall process costs. In dilute acid/base pretreatment, cellulases are suppressed by salt. As a result, large quantities of enzymes are required, which increases operating costs.

The mission of the U. S. Department of Energy (DOE) Joint Genome Institute is to advance genomics in support of the DOE missions related to clean energy generation and environmental characterization and cleanup. Supported by the DOE Office of Science, DOE JGI unites the expertise of five national laboratories -- Lawrence Berkeley, Lawrence Livermore, Los Alamos, Oak Ridge and Pacific Northwest -- along with the HudsonAlpha Institute for Biotechnology.

The Joint BioEnergy Institute (JBEI, is a scientific partnership led by the Lawrence Berkeley National Laboratory and including the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science and the Lawrence Livermore National Laboratory. JBEI’s primary scientific mission is to advance the development of the next generation of biofuels.

DEVELOPMENT STAGE: Proven principle. Recombinant proteins showed cellulase activity and are currently being incorporated into hydrolytic enzyme cocktails at JBEI.

STATUS: Published patent application US-2013-0023015-A1 available at Available for licensing or collaborative research.


Enhanced Ionic Liquid Biomass Pretreatment, EIO-2842

Acid Hydrolysis of Biomass and Increased Sugar Recovery by Solvent Extraction, EJIB-3030

Recovery of Sugars by Solvent Extraction, EJIB-2750


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