Applied Microbiology and Biotechnology

, Volume 74, Issue 2, pp 422–432 | Cite as

Proteomic profile changes in membranes of ethanol-tolerant Clostridium thermocellum

  • Taufika Islam Williams
  • Jennifer C. Combs
  • Bert C. Lynn
  • Herbert J. Strobel
Genomics and Proteomics


Clostridium thermocellum, a cellulolytic, thermophilic anaerobe, has potential for commercial exploitation in converting fibrous biomass to ethanol. However, ethanol concentrations above 1% (w/v) are inhibitory to growth and fermentation, and this limits industrial application of the organism. Recent work with ethanol-adapted strains suggested that protein changes occurred during ethanol adaptation, particularly in the membrane proteome. A two-stage Bicine-doubled sodium dodecyl sulfate-polyacrylamide gel electrophoresis protocol was designed to separate membrane proteins and circumvent problems associated with membrane protein analysis using traditional gel-based proteomics approaches. Wild-type and ethanol-adapted C. thermocellum membranes displayed similar spot diversity and approximately 60% of proteins identified from purified membrane fractions were observed to be differentially expressed in the two strains. A majority (73%) of differentially expressed proteins were down-regulated in the ethanol-adapted strain. Based on putative identifications, a significant proportion of these down-regulated proteins were involved with carbohydrate transport and metabolism. Approximately one-third of the up-regulated proteins in the ethanol-adapted species were associated with chemotaxis and signal transduction. Overall, the results suggested that membrane-associated proteins in the ethanol-adapted strain are either being synthesized in lower quantities or not properly incorporated into the cell membrane.


Clostridium thermocellum Ethanol tolerance Proteomics 



These authors thank the University of Kentucky Mass Spectrometry Facility ( for laboratory resources. This work was supported by the National Research Initiative of the USDA-CSREES, Grant # 2004-35504-14678.


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Copyright information

© Springer-Verlag 2006

Authors and Affiliations

  • Taufika Islam Williams
    • 1
    • 3
  • Jennifer C. Combs
    • 2
  • Bert C. Lynn
    • 1
  • Herbert J. Strobel
    • 2
  1. 1.Department of ChemistryUniversity of KentuckyLexingtonUSA
  2. 2.Department of Animal and Food SciencesUniversity of KentuckyLexingtonUSA
  3. 3.Department of ChemistryNorth Carolina State UniversityRaleighUSA

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