Proteomic profile changes in membranes of ethanol-tolerant Clostridium thermocellum

• Published in: Applied microbiology and biotechnology Vol. 74; no. 2; pp. 422 - 432
• Main Authors: Williams, Taufika Islam, Combs, Jennifer C, Lynn, Bert C, Strobel, Herbert J
• Format: Journal Article
• Language: English
• Published: Berlin Berlin/Heidelberg : Springer-Verlag 01.02.2007; Springer; Springer Nature B.V
• Subjects: Bacteria; Bacterial Proteins - genetics; Bacterial Proteins - metabolism; Biological and medical sciences; Biotechnology; Cell Membrane - metabolism; Clostridium thermocellum; Clostridium thermocellum - drug effects; Clostridium thermocellum - genetics; Clostridium thermocellum - growth & development; Clostridium thermocellum - metabolism; Ethanol; Ethanol - pharmacology; Ethanol tolerance; Fermentation; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Bacterial; Industrial Microbiology - methods; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membranes; Proteins; Proteomics; Signal transduction; Ethanol; Clostridium thermocellum; Clostridiaceae; Proteomics; Clostridiales; Tolerance; Bacteria; Membrane
• ISSN: 0175-7598; 1432-0614
• DOI: 10.1007/s00253-006-0689-7

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.