Thermophilic lignocellulose deconstruction

Authors

  • Sara E. Blumer-Schuette,

    1. Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
    2. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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  • Steven D. Brown,

    1. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
    2. Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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  • Kyle B. Sander,

    1. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
    2. Bredesen Center for Interdisciplinary Research and Graduate Education, University of Tennessee, Knoxville, TN, USA
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  • Edward A. Bayer,

    1. Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
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  • Irina Kataeva,

    1. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
    2. Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
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  • Jeffrey V. Zurawski,

    1. Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
    2. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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  • Jonathan M. Conway,

    1. Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
    2. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
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  • Michael W. W. Adams,

    1. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
    2. Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, USA
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  • Robert M. Kelly

    Corresponding author
    1. Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, USA
    2. Bioenergy Science Center, Oak Ridge National Laboratory, Oak Ridge, TN, USA
    • Correspondence: Robert M. Kelly, Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC 27695-7905, USA. Tel.: +1 919 515 6396; fax: +1 919 515 3465; e-mail: rmkelly@ncsu.edu

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Abstract

Thermophilic microorganisms are attractive candidates for conversion of lignocellulose to biofuels because they produce robust, effective, carbohydrate-degrading enzymes and survive under harsh bioprocessing conditions that reflect their natural biotopes. However, no naturally occurring thermophile is known that can convert plant biomass into a liquid biofuel at rates, yields and titers that meet current bioprocessing and economic targets. Meeting those targets requires either metabolically engineering solventogenic thermophiles with additional biomass-deconstruction enzymes or engineering plant biomass degraders to produce a liquid biofuel. Thermostable enzymes from microorganisms isolated from diverse environments can serve as genetic reservoirs for both efforts. Because of the sheer number of enzymes that are required to hydrolyze plant biomass to fermentable oligosaccharides, the latter strategy appears to be the preferred route and thus has received the most attention to date. Thermophilic plant biomass degraders fall into one of two categories: cellulosomal (i.e. multienzyme complexes) and noncellulosomal (i.e. ‘free’ enzyme systems). Plant-biomass-deconstructing thermophilic bacteria from the genera Clostridium (cellulosomal) and Caldicellulosiruptor (noncellulosomal), which have potential as metabolic engineering platforms for producing biofuels, are compared and contrasted from a systems biology perspective.

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