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The Southeastern Regional
Sun Grant Center
2506 Jacob Drive
Knoxville, TN 37996-4570
Phone: (865) 946-1124
Fax: (865) 946-1109
Email: sungrant@tennessee.edu

Regional Competitive Grants

Project Title: Bacterial adaptations for enhanced cellulose utilization: a systems approach

 

Principal Investigators and affiliations:

  • PI: Sue Nokes (University of Kentucky, Department of Biosystems and Ag Engineering)
  • Co-PI: Barabara Knutson (University of Kentucky, Department of Chemical and Materials Engineering)
  • Co-PI: Herbert Strobel (University of Kentucky, Department of Animal and Food Science)
  • Co-PI: Bert Lynn (University of Kentucky, Department of Chemistry)

Start Date: 9/1/2007      End Date: 8/31/2010

Project Abstract:

Redirecting carbon flux towards a desired product without disturbing the overall cell physiology is a complex task. Metabolism in anaerobic microorganisms is a highly-branched and inter-connected system that connects stoichiometrric relationships, reducing equivalents and energy transport.

Our overall objective is to identify phenotypic regions of ethanol-only production achieved through environmental perturbations, with development of a predictive model that is applicable to both environmental and genetic manipulation of C. thermocellum product selectivity. Specific Aim 1: Map the dissolved gas/dilution rate parameter space of fermentation end product profiles, using a high pressure chemostat, and identify regions which move metabolism towards ethanol-only production. Specific Aim 2: Incorporate metabolic flux model into whole-cell model that accounts for growth (i. e., dilution) rate and dissolved gas effects on product selectivity. Specific Aim 3: Evaluate the predictive model by comparing actual and predicted metabolic profiles for a broad range of phenotypes.

Measurable changes in the product profile of C. thermocellum in response to growth (i. e., dilution) rate and aqueous H2 concentration will be achieved in continuous cultures using a pressurized chemostat. The selectivity of C. thermocellum (in particular, the ethanol/acetate or E/A ratio) in response to these environmental perturbations will be determined and described using a surface response . This surface response will be used to identify and verify environmental perturbations which move the fermentation toward ethanol-only production.

Success of this research will establish novel environmental perturbations and analysis tools for the inverse metabolic engineering of C. thermocellum to enhance its commercial viability for consolidated bioprocessing, in particular. More generally, this research will develop a unique quantitative systems biology approach to achieve desired product selectivities in response to environmental and genetic manipulations.

Reports and Publications:

Quarter 4 2007 - Quarter 1 2008
Quarter 2 - 2008
Quarters 3-4 - 2008

Quarter 1 - 2009
Quarter 2 - 2009