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Title: A Thermophilic Ionic Liquid-Tolerant Cellulase Cocktail for the Production of Cellulosic Biofuels

Journal Article · · PLoS ONE
 [1];  [2];  [2];  [3];  [2];  [2];  [2];  [4];  [2];  [1];  [2];  [2];  [2];  [2];  [2];  [1];  [1]
  1. Sandia National Lab. (SNL-CA), Livermore, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Generation of biofuels from sugars in lignocellulosic biomass is a promising alternative to liquid fossil fuels, but efficient and inexpensive bioprocessing configurations must be developed to make this technology commercially viable. One of the major barriers to commercialization is the recalcitrance of plant cell wall polysaccharides to enzymatic hydrolysis. Biomass pretreatment with ionic liquids (ILs) enables efficient saccharification of biomass, but residual ILs inhibit both saccharification and microbial fuel production, requiring extensive washing after IL pretreatment. Pretreatment itself can also produce biomass-derived inhibitory compounds that reduce microbial fuel production. Therefore, there are multiple points in the process from biomass to biofuel production that must be interrogated and optimized to maximize fuel production. Here, we report the development of an IL-tolerant cellulase cocktail by combining thermophilic bacterial glycoside hydrolases produced by a mixed consortia with recombinant glycoside hydrolases. This enzymatic cocktail saccharifies IL-pretreated biomass at higher temperatures and in the presence of much higher IL concentrations than commercial fungal cocktails. Sugars obtained from saccharification of IL-pretreated switchgrass using this cocktail can be converted into biodiesel (fatty acid ethyl-esters or FAEEs) by a metabolically engineered strain of E. coli. During these studies, we found that this biodiesel-producing E. coli strain was sensitive to ILs and inhibitors released by saccharification. This cocktail will enable the development of novel biomass to biofuel bioprocessing configurations that may overcome some of the barriers to production of inexpensive cellulosic biofuels.

Research Organization:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23), Biological Systems Science Division (SC-23.2 )
Grant/Contract Number:
AC02-05CH11231
OSTI ID:
1511337
Journal Information:
PLoS ONE, Vol. 7, Issue 5; ISSN 1932-6203
Publisher:
Public Library of ScienceCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 140 works
Citation information provided by
Web of Science

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Microbial diversity of thermophiles with biomass deconstruction potential in a foliage‐rich hot spring journal March 2018
Forward genetics screen coupled with whole-genome resequencing identifies novel gene targets for improving heterologous enzyme production in Aspergillus niger journal January 2018
Genomic and physiological analyses reveal that extremely thermophilic Caldicellulosiruptor changbaiensis deploys uncommon cellulose attachment mechanisms journal August 2019
The amazing potential of fungi: 50 ways we can exploit fungi industrially journal July 2019
Exceptional solvent tolerance in Yarrowia lipolytica is enhanced by sterols journal July 2019
Refining the phylum Chlorobi by resolving the phylogeny and metabolic potential of the representative of a deeply branching, uncultivated lineage journal September 2015
An auto-inducible mechanism for ionic liquid resistance in microbial biofuel production journal March 2014
Non-aqueous homogenous biocatalytic conversion of polysaccharides in ionic liquids using chemically modified glucosidase journal June 2018
Understanding the role of water during ionic liquid pretreatment of lignocellulose: co-solvent or anti-solvent? journal January 2014
Enzymatic hydrolysis of lignocellulosic polysaccharides in the presence of ionic liquids journal January 2015
A loop engineering strategy improves laccase lcc2 activity in ionic liquid and aqueous solution journal January 2018
An integrated droplet-digital microfluidic system for on-demand droplet creation, mixing, incubation, and sorting journal January 2019
Cellulose solvent-based pretreatment for enhanced second-generation biofuel production: a review journal January 2019
Community dynamics of cellulose-adapted thermophilic bacterial consortia: Cellulose-adapted consortia journal June 2013
Thermophilic enrichment of microbial communities in the presence of the ionic liquid 1-ethyl-3-methylimidazolium acetate journal October 2012
Ionic Liquids Impact the Bioenergy Feedstock-Degrading Microbiome and Transcription of Enzymes Relevant to Polysaccharide Hydrolysis journal December 2016
Chemical Pretreatment Methods for the Production of Cellulosic Ethanol: Technologies and Innovations journal January 2013
Impact of high biomass loading on ionic liquid pretreatment journal January 2013
Discovery and characterization of ionic liquid-tolerant thermophilic cellulases from a switchgrass-adapted microbial community journal January 2014
Fatty acid synthesis in Escherichia coli and its applications towards the production of fatty acid based biofuels journal January 2014
Understanding cost drivers and economic potential of two variants of ionic liquid pretreatment for cellulosic biofuel production journal January 2014
Metasecretome analysis of a lignocellulolytic microbial consortium grown on wheat straw, xylan and xylose journal December 2015
Using the β-glucosidase catalyzed reaction product glucose to improve the ionic liquid tolerance of β-glucosidases journal March 2016
Metagenomic and metaproteomic analyses of a corn stover-adapted microbial consortium EMSD5 reveal its taxonomic and enzymatic basis for degrading lignocellulose journal November 2016
Expression of naturally ionic liquid-tolerant thermophilic cellulases in Aspergillus niger journal December 2017
Recent trends in ionic liquid (IL) tolerant enzymes and microorganisms for biomass conversion journal October 2013
Developing Efficient Thermophilic Cellulose Degrading Consortium for Glucose Production From Different Agro-Residues journal July 2019
Simultaneous saccharification and fermentation of cellulose in ionic liquid for efficient production of α-ketoglutaric acid by Yarrowia lipolytica journal March 2015
Functional Expression of a Thermostable Endoglucanase from Thermoascus aurantiacus RCKK in Pichia pastoris X-33 and Its Characterization journal August 2018
Characterization of three plant biomass-degrading microbial consortia by metagenomics- and metasecretomics-based approaches journal July 2016
Phylogenomically Guided Identification of Industrially Relevant GH1 β-Glucosidases through DNA Synthesis and Nanostructure-Initiator Mass Spectrometry journal July 2014
A bacterial pioneer produces cellulase complexes that persist through community succession journal November 2017
Isolation and Characterization of Bacterial Cellulase Producers for Biomass Deconstruction: A Microbiology Laboratory Course journal January 2019
Scale-up and evaluation of high solid ionic liquid pretreatment and enzymatic hydrolysis of switchgrass journal January 2013
Exploring the Synergy between Cellobiose Dehydrogenase from Phanerochaete chrysosporium and Cellulase from Trichoderma reesei journal April 2016

Figures / Tables (9)