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Title: The exometabolome of Clostridium thermocellum reveals overflow metabolism at high cellulose loading

Abstract

Background: Clostridium thermocellum is a model thermophilic organism for the production of biofuels from lignocellulosic substrates. The majority of publications studying the physiology of this organism use substrate concentrations of ≤10 g/L. However, industrially relevant concentrations of substrate start at 100 g/L carbohydrate, which corresponds to approximately 150 g/L solids. To gain insight into the physiology of fermentation of high substrate concentrations, we studied the growth on, and utilization of high concentrations of crystalline cellulose varying from 50 to 100 g/L by C. thermocellum. Results: Using a defined medium, batch cultures of C. thermocellum achieved 93% conversion of cellulose (Avicel) initially present at 100 g/L. The maximum rate of substrate utilization increased with increasing substrate loading. During fermentation of 100 g/L cellulose, growth ceased when about half of the substrate had been solubilized. However, fermentation continued in an uncoupled mode until substrate utilization was almost complete. In addition to commonly reported fermentation products, amino acids - predominantly L-valine and L-alanine - were secreted at concentrations up to 7.5 g/L. Uncoupled metabolism was also accompanied by products not documented previously for C. thermocellum, including isobutanol, meso- and RR/SS-2,3-butanediol and trace amounts of 3-methyl-1-butanol, 2-methyl-1-butanol and 1-propanol. We hypothesize that C. thermocellummore » uses overflow metabolism to balance its metabolism around the pyruvate node in glycolysis. In conclusion: C. thermocellum is able to utilize industrially relevant concentrations of cellulose, up to 93 g/L. We report here one of the highest degrees of crystalline cellulose utilization observed thus far for a pure culture of C. thermocellum, the highest maximum substrate utilization rate and the highest amount of isobutanol produced by a wild-type organism.« less

Authors:
 [1];  [2];  [1];  [3];  [4];  [4];  [5];  [6]
  1. Dartmouth College, Hanover, NH (United States). Thayer School of Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC)
  2. Mascoma Corp., Lebanon, NH (United States)
  3. Univ. of Wisconsin, Madison, WI (United States). Dept. of Bacteriology
  4. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Biosciences Division
  5. Delft Univ. of Technology (Netherlands)
  6. Dartmouth College, Hanover, NH (United States). Thayer School of Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC); Mascoma Corp., Lebanon, NH (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). BioEnergy Science Center (BESC)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1163586
Grant/Contract Number:  
AC05-00OR22725
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 1754-6834
Publisher:
BioMed Central
Country of Publication:
United States
Language:
English
Subject:
09 BIOMASS FUELS; Clostridium thermocellum; Cellulose fermentation; Isobutanol; 2,3-butanediol; Amino acids; High solids; Fusel alcohols

Citation Formats

Holwerda, Evert K., Thorne, Philip G., Olson, Daniel G., Amador-Noguez, Daniel, Engle, Nancy L., Tschaplinski, Timothy J., van Dijken, Johannes P., and Lynd, Lee R. The exometabolome of Clostridium thermocellum reveals overflow metabolism at high cellulose loading. United States: N. p., 2014. Web. doi:10.1186/s13068-014-0155-1.
Holwerda, Evert K., Thorne, Philip G., Olson, Daniel G., Amador-Noguez, Daniel, Engle, Nancy L., Tschaplinski, Timothy J., van Dijken, Johannes P., & Lynd, Lee R. The exometabolome of Clostridium thermocellum reveals overflow metabolism at high cellulose loading. United States. doi:10.1186/s13068-014-0155-1.
Holwerda, Evert K., Thorne, Philip G., Olson, Daniel G., Amador-Noguez, Daniel, Engle, Nancy L., Tschaplinski, Timothy J., van Dijken, Johannes P., and Lynd, Lee R. Tue . "The exometabolome of Clostridium thermocellum reveals overflow metabolism at high cellulose loading". United States. doi:10.1186/s13068-014-0155-1. https://www.osti.gov/servlets/purl/1163586.
@article{osti_1163586,
title = {The exometabolome of Clostridium thermocellum reveals overflow metabolism at high cellulose loading},
author = {Holwerda, Evert K. and Thorne, Philip G. and Olson, Daniel G. and Amador-Noguez, Daniel and Engle, Nancy L. and Tschaplinski, Timothy J. and van Dijken, Johannes P. and Lynd, Lee R.},
abstractNote = {Background: Clostridium thermocellum is a model thermophilic organism for the production of biofuels from lignocellulosic substrates. The majority of publications studying the physiology of this organism use substrate concentrations of ≤10 g/L. However, industrially relevant concentrations of substrate start at 100 g/L carbohydrate, which corresponds to approximately 150 g/L solids. To gain insight into the physiology of fermentation of high substrate concentrations, we studied the growth on, and utilization of high concentrations of crystalline cellulose varying from 50 to 100 g/L by C. thermocellum. Results: Using a defined medium, batch cultures of C. thermocellum achieved 93% conversion of cellulose (Avicel) initially present at 100 g/L. The maximum rate of substrate utilization increased with increasing substrate loading. During fermentation of 100 g/L cellulose, growth ceased when about half of the substrate had been solubilized. However, fermentation continued in an uncoupled mode until substrate utilization was almost complete. In addition to commonly reported fermentation products, amino acids - predominantly L-valine and L-alanine - were secreted at concentrations up to 7.5 g/L. Uncoupled metabolism was also accompanied by products not documented previously for C. thermocellum, including isobutanol, meso- and RR/SS-2,3-butanediol and trace amounts of 3-methyl-1-butanol, 2-methyl-1-butanol and 1-propanol. We hypothesize that C. thermocellum uses overflow metabolism to balance its metabolism around the pyruvate node in glycolysis. In conclusion: C. thermocellum is able to utilize industrially relevant concentrations of cellulose, up to 93 g/L. We report here one of the highest degrees of crystalline cellulose utilization observed thus far for a pure culture of C. thermocellum, the highest maximum substrate utilization rate and the highest amount of isobutanol produced by a wild-type organism.},
doi = {10.1186/s13068-014-0155-1},
journal = {Biotechnology for Biofuels},
number = 1,
volume = 7,
place = {United States},
year = {Tue Oct 21 00:00:00 EDT 2014},
month = {Tue Oct 21 00:00:00 EDT 2014}
}

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Cited by: 25 works
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Works referenced in this record:

KEGG: Kyoto Encyclopedia of Genes and Genomes
journal, January 2000

  • Kanehisa, Minoru; Goto, Susumu
  • Nucleic Acids Research, Vol. 28, Issue 1, p. 27-30
  • DOI: 10.1093/nar/28.1.27

Cellulase, Clostridia, and Ethanol
journal, March 2005

  • Demain, A. L.; Newcomb, M.; Wu, J. H. D.
  • Microbiology and Molecular Biology Reviews, Vol. 69, Issue 1, p. 124-154
  • DOI: 10.1128/MMBR.69.1.124-154.2005

Consolidated bioprocessing of cellulosic biomass: an update
journal, October 2005

  • Lynd, Lee R.; van Zyl, Willem H.; McBride, John E.
  • Current Opinion in Biotechnology, Vol. 16, Issue 5, p. 577-583
  • DOI: 10.1016/j.copbio.2005.08.009

High Ethanol Titers from Cellulose by Using Metabolically Engineered Thermophilic, Anaerobic Microbes
journal, September 2011

  • Argyros, D. Aaron; Tripathi, Shital A.; Barrett, Trisha F.
  • Applied and Environmental Microbiology, Vol. 77, Issue 23, p. 8288-8294
  • DOI: 10.1128/AEM.00646-11

Atypical Glycolysis in Clostridium thermocellum
journal, February 2013

  • Zhou, Jilai; Olson, Daniel G.; Argyros, D. Aaron
  • Applied and Environmental Microbiology, Vol. 79, Issue 9, p. 3000-3008
  • DOI: 10.1128/AEM.04037-12

Development of pyrF-Based Genetic System for Targeted Gene Deletion in Clostridium thermocellum and Creation of a pta Mutant
journal, August 2010

  • Tripathi, S. A.; Olson, D. G.; Argyros, D. A.
  • Applied and Environmental Microbiology, Vol. 76, Issue 19, p. 6591-6599
  • DOI: 10.1128/AEM.01484-10

Production of ethanol and xylitol from corn cobs by yeasts
journal, March 2001