Thermophilic enrichment of microbial communities in the presence of the ionic liquid 1-ethyl-3-methylimidazolium acetate

Authors

  • A.P. Reddy,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Biological and Agricultural Engineering, University of California-Davis, Davis, CA, USA
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  • C.W. Simmons,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Biological and Agricultural Engineering, University of California-Davis, Davis, CA, USA
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  • J. Claypool,

    1. Biological and Agricultural Engineering, University of California-Davis, Davis, CA, USA
    Current affiliation:
    1. Agricultural and Biosystems Engineering, Iowa State University, Ames, IA, USA
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  • L. Jabusch,

    1. Biological and Agricultural Engineering, University of California-Davis, Davis, CA, USA
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  • H. Burd,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
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  • M.Z. Hadi,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
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  • B.A. Simmons,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Physical and Life Sciences Directorate, Lawrence Livermore National Laboratory, Livermore, CA, USA
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  • S.W. Singer,

    1. Joint BioEnergy Institute, Emeryville, CA, USA
    2. Department of Biomass Science and Conversion Technology, Sandia National Laboratories, Livermore, CA, USA
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  • J.S. VanderGheynst

    Corresponding author
    1. Biological and Agricultural Engineering, University of California-Davis, Davis, CA, USA
    • Joint BioEnergy Institute, Emeryville, CA, USA
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Correspondence

Jean S. VanderGheynst, Department of Biological and Agricultural Engineering, University of California, Davis, CA 95616, USA. E-mail: jsvander@ucdavis.edu

Abstract

Aims

The aim of the study was to develop an approach to enrich ionic liquid tolerant micro-organisms that efficiently decompose lignocellulose in a thermophilic and high-solids environment.

Methods and Results

High-solids incubations were conducted, using compost as an inoculum source, to enrich for thermophilic communities that decompose switchgrass in the presence of the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]). Ionic liquid levels were increased from 0 to 6% on a total weight basis incrementally. Successful enrichment of a community that decomposed lignocellulose at 55°C in the presence of 6% [C2mim][OAc] was achieved, when the [C2mim][OAc] level was increased stepwise from 2% to 4% to 5% to 6%. Pyrosequencing results revealed a shift in the community and a sharp decrease in richness, when thermophilic conditions were applied.

Conclusions

A community tolerant to a thermophilic, high-solids environment containing 6% [C2mim][OAc] was enriched from compost. Gradually increasing [C2mim][OAc] concentrations allowed the community to adapt to [C2mim][OAc].

Significance and Impact of the Study

A successful approach to enrich communities that decompose lignocellulose under thermophilic high-solids conditions in the presence of elevated levels of [C2mim][OAc] has been developed. Communities yielded from this approach will provide resources for the discovery of enzymes and metabolic pathways relevant to biomass pretreatment and fuel production.

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