Enrichment of microbial communities tolerant to the ionic liquids tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate
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The aims of this study were to identify thermophilic microbial communities that degrade green waste in the presence of the ionic liquids (IL) tetrabutylphosphonium chloride and tributylethylphosphonium diethylphosphate and examine preservation methods for IL-tolerant communities. High-solids incubations with stepwise increases in IL concentration were conducted to enrich for thermophilic IL-tolerant communities that decomposed green waste. 16S rRNA sequencing of enriched communities revealed microorganisms capable of tolerating high levels of IL. Cryogenic preservation of enriched communities reduced the IL tolerance of the community and decreased the relative abundance of IL-tolerant organisms. The use of cryoprotectants did not have an effect on microbial activity on green waste of the stored community. A successful approach was developed to enrich communities that decompose green waste in thermophilic high-solids environments in the presence of IL. Alternative community storage and revival methods are necessary for maintenance and recovery of IL-tolerant communities. The enriched communities provide a targeted source of enzymes for the bioconversion of IL-pretreated green waste for conversion to biofuels.
KeywordsPhosphonium ionic liquids Microbial communities Bioenergy High-solids Pretreatment Storage
Compliance with ethical standards
This work was supported by National Institute of Food and Agriculture project CA-D-BAE-2228-RR, the UC Lab Fees Research Program under project #237496 and completed as part of the Joint BioEnergy Institute, supported by the US Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the US Department of Energy. Sara Pace and Duff Harrold were partially supported by the NSF GK-12 project under DGE-0948021. Sequencing was conducted by the Joint Genome Institute, which is supported by the Office of Science of the US Department of Energy under Contract DE-AC02-05CH11231.
Conflict of interest
Sara Pace, Shannon J. Ceballos, Duff Harrold, Whitney Stannard, Blake A. Simmons, Steven W. Singer, Michael P. Thelen, and Jean S. VanderGheynst declare that they have no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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