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Title: Clostridium thermocellum Transcriptomic Profiles after Exposure to Furfural or Heat Stress

Abstract

Background The thermophilic anaerobe Clostridium thermocellum is a candidate consolidated bioprocessing (CBP)biocatalyst for cellulosic ethanol production. It is capable of both cellulose solubilization and its fermentation to produce lignocellulosic ethanol. Intolerance to stresses routinely encountered during industrial fermentations may hinder the commercial development of this organism. A previous C. thermocellum ethanol stress study showed that largest transcriptomic response was in genes and proteins related to nitrogen uptake and metabolism. Results In this study, C. thermocellum was grown to mid-exponential phase and treated with furfural or heat to a final concentration of 3 g.L-1 or 68 C respectively to investigate general and specific physiological and regulatory stress responses. Samples were taken at 10, 30, 60 and 120 min post-shock, and from untreated control fermentations, for transcriptomic analyses and fermentation product determinations and compared to a published dataset from an ethanol stress study. Urea uptake genes were induced following furfural stress, but not to the same extent as ethanol stress and transcription from these genes was largely unaffected by heat stress. The largest transcriptomic response to furfural stress was genes for sulfate transporter subunits and enzymes in the sulfate assimilatory pathway, although these genes were also affected late in the heat andmore » ethanol stress responses. Lactate production was higher in furfural treated culture, although the lactate dehydrogenase gene was not differentially expressed under this condition. Other redox related genes such as a copy of the rex gene, a bifunctional acetaldehyde-CoA/alcohol dehydrogenase and adjacent genes did show lower expression after furfural stress compared to the control, heat and ethanol fermentation profiles. Heat stress induced expression from chaperone related genes and overlap was observed with the responses to the other stresses. This study suggests the involvement of C. thermocellum genes with functions in oxidative stress protection, electron transfer, detoxification, sulfur and nitrogen acquisition, and DNA repair mechanisms in its stress responses and the use of different regulatory networks to coordinate and control adaptation. Conclusions This study has identified C. thermocellum gene regulatory motifs and aspects of physiology and gene regulation for further study. The nexus between future systems biology studies and recently developed genetic tools for C. thermocellum offers the potential for more rapid strain development and for broader insights into this organism s physiology and regulation.« less

Authors:
 [1];  [1];  [2];  [1];  [1];  [2];  [1]
  1. ORNL
  2. University of Georgia, Athens, GA
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1093113
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Biotechnology for Biofuels
Additional Journal Information:
Journal Volume: 6; Journal Issue: 1; Journal ID: ISSN 1754--6834
Country of Publication:
United States
Language:
English

Citation Formats

Wilson, Charlotte M, Yang, Shihui, Rodriguez, Jr., Miguel, Ma, Qin, Johnson, Courtney M, Dice, Lezlee T, Xu, Ying, and Brown, Steven D. Clostridium thermocellum Transcriptomic Profiles after Exposure to Furfural or Heat Stress. United States: N. p., 2013. Web. doi:10.1186/1754-6834-6-131.
Wilson, Charlotte M, Yang, Shihui, Rodriguez, Jr., Miguel, Ma, Qin, Johnson, Courtney M, Dice, Lezlee T, Xu, Ying, & Brown, Steven D. Clostridium thermocellum Transcriptomic Profiles after Exposure to Furfural or Heat Stress. United States. doi:10.1186/1754-6834-6-131.
Wilson, Charlotte M, Yang, Shihui, Rodriguez, Jr., Miguel, Ma, Qin, Johnson, Courtney M, Dice, Lezlee T, Xu, Ying, and Brown, Steven D. Tue . "Clostridium thermocellum Transcriptomic Profiles after Exposure to Furfural or Heat Stress". United States. doi:10.1186/1754-6834-6-131.
@article{osti_1093113,
title = {Clostridium thermocellum Transcriptomic Profiles after Exposure to Furfural or Heat Stress},
author = {Wilson, Charlotte M and Yang, Shihui and Rodriguez, Jr., Miguel and Ma, Qin and Johnson, Courtney M and Dice, Lezlee T and Xu, Ying and Brown, Steven D},
abstractNote = {Background The thermophilic anaerobe Clostridium thermocellum is a candidate consolidated bioprocessing (CBP)biocatalyst for cellulosic ethanol production. It is capable of both cellulose solubilization and its fermentation to produce lignocellulosic ethanol. Intolerance to stresses routinely encountered during industrial fermentations may hinder the commercial development of this organism. A previous C. thermocellum ethanol stress study showed that largest transcriptomic response was in genes and proteins related to nitrogen uptake and metabolism. Results In this study, C. thermocellum was grown to mid-exponential phase and treated with furfural or heat to a final concentration of 3 g.L-1 or 68 C respectively to investigate general and specific physiological and regulatory stress responses. Samples were taken at 10, 30, 60 and 120 min post-shock, and from untreated control fermentations, for transcriptomic analyses and fermentation product determinations and compared to a published dataset from an ethanol stress study. Urea uptake genes were induced following furfural stress, but not to the same extent as ethanol stress and transcription from these genes was largely unaffected by heat stress. The largest transcriptomic response to furfural stress was genes for sulfate transporter subunits and enzymes in the sulfate assimilatory pathway, although these genes were also affected late in the heat and ethanol stress responses. Lactate production was higher in furfural treated culture, although the lactate dehydrogenase gene was not differentially expressed under this condition. Other redox related genes such as a copy of the rex gene, a bifunctional acetaldehyde-CoA/alcohol dehydrogenase and adjacent genes did show lower expression after furfural stress compared to the control, heat and ethanol fermentation profiles. Heat stress induced expression from chaperone related genes and overlap was observed with the responses to the other stresses. This study suggests the involvement of C. thermocellum genes with functions in oxidative stress protection, electron transfer, detoxification, sulfur and nitrogen acquisition, and DNA repair mechanisms in its stress responses and the use of different regulatory networks to coordinate and control adaptation. Conclusions This study has identified C. thermocellum gene regulatory motifs and aspects of physiology and gene regulation for further study. The nexus between future systems biology studies and recently developed genetic tools for C. thermocellum offers the potential for more rapid strain development and for broader insights into this organism s physiology and regulation.},
doi = {10.1186/1754-6834-6-131},
journal = {Biotechnology for Biofuels},
issn = {1754--6834},
number = 1,
volume = 6,
place = {United States},
year = {2013},
month = {1}
}