Proteomic profile changes in membranes of ethanol-tolerant Clostridium thermocellum

Taufika Islam Williams, Jennifer C. Combs, Bert C. Lynn, Herbert J. Strobel

Research output: Contribution to journalArticlepeer-review

65 Scopus citations


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.

Original languageEnglish
Pages (from-to)422-432
Number of pages11
JournalApplied Microbiology and Biotechnology
Issue number2
StatePublished - Feb 2007

Bibliographical note

Funding Information:
Acknowledgements 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.


  • Clostridium thermocellum
  • Ethanol tolerance
  • Proteomics

ASJC Scopus subject areas

  • Biotechnology
  • Applied Microbiology and Biotechnology


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