Development of Genetically Engineered Stress Tolerant Ethanologenic Yeasts Using Integrated Functional Genomics for Effective Biomass Conversion to Ethanol

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• Development of Genetically Engineered Stress
  Tolerant Ethanologenic Yeasts Using Integrated
  Functional Genomics for Effective Biomass
  Conversion to Ethanol
• Z. Lewis Liu
• National Center for Agricultural Utilization
  Research, USDA-ARS

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Outlines

• INTRODUCTION
• - Biomass Pretreatment Generates Fermentation
  Inhibitors
• - Microbial Performance is the Key for
  Improvement
• - Why Integrated Functional Genomics?
• METABOLIC CONVERSION PATHWAYS
• - Furfural
• - HMF (5-Hydroxymethylfurfural)
• gt Identification of 2,5-bis-hydroxymethylfuran
• gt Biotransformation of HMF
• ADAPTIVE RESPONSE
• POTENTIAL FOR YEAST TOLERANCE IMPROVEMENT
• - Enhanced Biotransformation
• - Tolerance Improvement Potential
• BYPRODUCT UTILIZATION ISSUES

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Biomass Pretreatment Generates Fermentation
Inhibitors
100 potential inhibitory compounds Represen
tative inhibitors Furfural HMF
(5-Hydroxymethylfurfural)
Glucose
Cellulose
HMF
Biomass
Dehydration
Hemicellulose
Furfural
Xylose Arabinose
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Microbial Performance is the Key for Improvement

• Fast Life Cycle
• Genetic Diversity
• Biocatalyst
• Bioengine
• Economic Cost

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Ethanol Fermentation Process
Ethanol and Byproducts
The Black Box?
Input Materials
Anaerobic Microbial Fermentation
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Potential for Tolerance Improvement (cont.)
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Enhanced Biotransformation Enhanced
Tolerance Enhanced Detoxification
IMPROVEMENT POTENTIAL
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Tolerance Mechanisms by Functional Genomics
Genomic Expression
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Genomic Expression (cont.)
Gene expression response to HMF Gene expression response to HMF
Initial response Over time responses Gene number
Repressed Repressed 203
No change Repressed quickly 55
No change Repressed slowly 30
No change No change 54
Enhanced Repressed 35
Enhanced Back to neutral 37
Enhanced Enhanced 15
? 429
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