Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis

ABSTRACT Ionic liquid (IL) pretreatment is a promising approach for the conversion of lignocellulose to biofuels. The toxicity of residual IL, however, negatively impacts the performance of industrial enzymes and microorganisms in hydrolysis and fermentation. In this study, a thermophilic microbial...

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Autores principales:	Yu-Wei Wu, Brendan Higgins, Chaowei Yu, Amitha P. Reddy, Shannon Ceballos, Lawrence D. Joh, Blake A. Simmons, Steven W. Singer, Jean S. VanderGheynst
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2016
Materias:	1-ethyl-3-methylimidazolium acetate cellulase hemicellulase ionic liquid Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/b2000b5e67e449f9a21580949e156f26
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spelling	oai:doaj.org-article:b2000b5e67e449f9a21580949e156f262021-12-02T18:39:34ZIonic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis10.1128/mSystems.00120-162379-5077https://doaj.org/article/b2000b5e67e449f9a21580949e156f262016-12-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mSystems.00120-16https://doaj.org/toc/2379-5077ABSTRACT Ionic liquid (IL) pretreatment is a promising approach for the conversion of lignocellulose to biofuels. The toxicity of residual IL, however, negatively impacts the performance of industrial enzymes and microorganisms in hydrolysis and fermentation. In this study, a thermophilic microbial community was cultured on switchgrass amended with various levels of the ionic liquid 1-ethyl-3-methylimidazolium acetate. Changes in the microbial community composition and transcription of genes relevant to IL tolerance and lignocellulose hydrolysis were quantified. Increasing the level of IL to 0.1% (wt) led to increased levels of relative abundance and transcription in organisms of the phylum Firmicutes. Interestingly, IL concentrations of up to 1% (wt) also resulted in greater xylanase transcription and enzyme activity as well as increased transcription of endoglucanase, beta-glucosidase, and IL tolerance genes compared to communities without IL. IL levels above 1% (wt) resulted in decreased enzyme activity and transcription of genes involved in lignocellulose hydrolysis. The results indicate that moderate levels of IL select for thermophilic microorganisms that not only tolerate IL but also effectively hydrolyze lignocellulose from switchgrass. Discovery of IL-tolerant organisms and enzymes is critical for the development of biological processes that convert IL-pretreated biomass to biofuels and chemicals. Employing metatranscriptomic analysis of enrichment cultures can facilitate the discovery of microorganisms and enzymes that may be active in the presence of toxic compounds such as ionic liquids. IMPORTANCE Pretreatment using ionic liquids (IL) is a promising approach for the conversion of lignocellulose to biofuels. Because IL can be inhibitory to enzymes and microorganisms involved in downstream hydrolysis and fermentation steps, discovery of IL-tolerant organisms and enzymes is critical for advancing this technology. Employing metatranscriptomics in the analysis of IL-enriched cultures facilitated tracking of dynamic changes in a complex microbial community at the level of gene transcription and doing so with genome resolution. Specific organisms were discovered that could simultaneously tolerate a moderate IL concentration and transcribe a diverse array of cellulolytic enzymes. Gene sequences of cellulolytic enzymes and efflux pumps from those same organisms were also identified, providing important resources for future research on engineering IL-tolerant organisms and enzymes.Yu-Wei WuBrendan HigginsChaowei YuAmitha P. ReddyShannon CeballosLawrence D. JohBlake A. SimmonsSteven W. SingerJean S. VanderGheynstAmerican Society for Microbiologyarticle1-ethyl-3-methylimidazolium acetatecellulasehemicellulaseionic liquidMicrobiologyQR1-502ENmSystems, Vol 1, Iss 6 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	1-ethyl-3-methylimidazolium acetate cellulase hemicellulase ionic liquid Microbiology QR1-502
spellingShingle	1-ethyl-3-methylimidazolium acetate cellulase hemicellulase ionic liquid Microbiology QR1-502 Yu-Wei Wu Brendan Higgins Chaowei Yu Amitha P. Reddy Shannon Ceballos Lawrence D. Joh Blake A. Simmons Steven W. Singer Jean S. VanderGheynst Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
description	ABSTRACT Ionic liquid (IL) pretreatment is a promising approach for the conversion of lignocellulose to biofuels. The toxicity of residual IL, however, negatively impacts the performance of industrial enzymes and microorganisms in hydrolysis and fermentation. In this study, a thermophilic microbial community was cultured on switchgrass amended with various levels of the ionic liquid 1-ethyl-3-methylimidazolium acetate. Changes in the microbial community composition and transcription of genes relevant to IL tolerance and lignocellulose hydrolysis were quantified. Increasing the level of IL to 0.1% (wt) led to increased levels of relative abundance and transcription in organisms of the phylum Firmicutes. Interestingly, IL concentrations of up to 1% (wt) also resulted in greater xylanase transcription and enzyme activity as well as increased transcription of endoglucanase, beta-glucosidase, and IL tolerance genes compared to communities without IL. IL levels above 1% (wt) resulted in decreased enzyme activity and transcription of genes involved in lignocellulose hydrolysis. The results indicate that moderate levels of IL select for thermophilic microorganisms that not only tolerate IL but also effectively hydrolyze lignocellulose from switchgrass. Discovery of IL-tolerant organisms and enzymes is critical for the development of biological processes that convert IL-pretreated biomass to biofuels and chemicals. Employing metatranscriptomic analysis of enrichment cultures can facilitate the discovery of microorganisms and enzymes that may be active in the presence of toxic compounds such as ionic liquids. IMPORTANCE Pretreatment using ionic liquids (IL) is a promising approach for the conversion of lignocellulose to biofuels. Because IL can be inhibitory to enzymes and microorganisms involved in downstream hydrolysis and fermentation steps, discovery of IL-tolerant organisms and enzymes is critical for advancing this technology. Employing metatranscriptomics in the analysis of IL-enriched cultures facilitated tracking of dynamic changes in a complex microbial community at the level of gene transcription and doing so with genome resolution. Specific organisms were discovered that could simultaneously tolerate a moderate IL concentration and transcribe a diverse array of cellulolytic enzymes. Gene sequences of cellulolytic enzymes and efflux pumps from those same organisms were also identified, providing important resources for future research on engineering IL-tolerant organisms and enzymes.
format	article
author	Yu-Wei Wu Brendan Higgins Chaowei Yu Amitha P. Reddy Shannon Ceballos Lawrence D. Joh Blake A. Simmons Steven W. Singer Jean S. VanderGheynst
author_facet	Yu-Wei Wu Brendan Higgins Chaowei Yu Amitha P. Reddy Shannon Ceballos Lawrence D. Joh Blake A. Simmons Steven W. Singer Jean S. VanderGheynst
author_sort	Yu-Wei Wu
title	Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
title_short	Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
title_full	Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
title_fullStr	Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
title_full_unstemmed	Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis
title_sort	ionic liquids impact the bioenergy feedstock-degrading microbiome and transcription of enzymes relevant to polysaccharide hydrolysis
publisher	American Society for Microbiology
publishDate	2016
url	https://doaj.org/article/b2000b5e67e449f9a21580949e156f26
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Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis

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