title: Clostridium thermocellum ATCC27405 transcriptomic, metabolomic and proteomic profiles after ethanol stress.
abstract: BACKGROUND
  Clostridium thermocellum is a candidate consolidated bioprocessing biocatalyst, which is a microorganism that expresses enzymes for both cellulose hydrolysis and its fermentation to produce fuels such as lignocellulosic ethanol. However, C. thermocellum is relatively sensitive to ethanol compared to ethanologenic microorganisms such as yeast and Zymomonas mobilis that are used in industrial fermentations but do not possess native enzymes for industrial cellulose hydrolysis.
  
  
  RESULTS
  In this study, C. thermocellum was grown to mid-exponential phase and then treated with ethanol to a final concentration of 3.9 g/L to investigate its physiological and regulatory responses to ethanol stress. Samples were taken pre-shock and 2, 12, 30, 60, 120, and 240 min post-shock, and from untreated control fermentations for systems biology analyses. Cell growth was arrested by ethanol supplementation with intracellular accumulation of carbon sources such as cellobiose, and sugar phosphates, including fructose-6-phosphate and glucose-6-phosphate. The largest response of C. thermocellum to ethanol shock treatment was in genes and proteins related to nitrogen uptake and metabolism, which is likely important for redirecting the cells physiology to overcome inhibition and allow growth to resume.
  
  
  CONCLUSIONS
  This study suggests possible avenues for metabolic engineering and provides comprehensive, integrated systems biology datasets that will be useful for future metabolic modeling and strain development endeavors.
authors: Biosciences Division, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, USA.
authors: Shihui
authors: S
authors: Yang
authors: Richard J
authors: RJ
authors: Giannone
authors: Lezlee
authors: L
authors: Dice
authors: Zamin K
authors: ZK
authors: Yang
authors: Nancy L
authors: NL
authors: Engle
authors: Timothy J
authors: TJ
authors: Tschaplinski
authors: Robert L
authors: RL
authors: Hettich
authors: Steven D
authors: SD
authors: Brown
mesh_terms: D002851:Chromatography, High Pressure Liquid; D048013:Acetivibrio thermocellus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D019295:Computational Biology; D000431:Ethanol / Q000737:chemistry*; D005285:Fermentation; D008401:Gas Chromatography-Mass Spectrometry; D055442:Metabolome; D020411:Oligonucleotide Array Sequence Analysis; D020543:Proteome / Q000032:analysis*; D012329:RNA, Bacterial / Q000235:genetics; D013312:Stress, Physiological; D049490:Systems Biology; D053719:Tandem Mass Spectrometry; D059467:Transcriptome
chemical_list: D020543:Proteome; D012329:RNA, Bacterial; D000431:Ethanol