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Yeast Hardening for Cellulosic Ethanol production. Bianca A. Brandt Supervisor: Prof J Gorgens Co-Supervisor: Prof WH Van Zyl Department of Process Engineering University of Stellenbosch. Energy Postgraduate Conference 2013. Introduction.

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yeast hardening for cellulosic ethanol production

Yeast Hardening for Cellulosic Ethanol production

Bianca A. Brandt

Supervisor: Prof J Gorgens

Co-Supervisor: Prof WH Van Zyl

Department of Process Engineering

University of Stellenbosch

Energy Postgraduate Conference 2013

introduction
Introduction
  • Growing global move towards sustainable green energy production
    • spurred by dependence on rapidly depleting finite fossil fuels
    • environmental and socio-economic concerns
  • Studies into Alternative Clean, Renewable and Sustainable energy resources:
    • solar-electric/thermal, hydroelectric, geothermal, tidal, wave, wind and ocean thermal power systems
    • furthermore, a great deal of work has gone into the development of biofuels
introduction1
Introduction
  • Why Biofuels?
    • vehicular transportation- energy stored easier in form of combustible hydrocarbons then as electricity or heat
    • compatible with current distribution systems
    • supplement and replace fossil fuels
  • A range of bio-fuels are currently being investigated
  • Bioethanol - benchmark biofuel
    • production based on a proven low cost technological platform
    • Brazil and USA - cost effective 1st generation bioethanol
    • sugar and starch
  • 2nd generation bioethanol from lignocelluloses
cellulosic bioethanol
Cellulosic Bioethanol
  • Bioethanol from Lignocellulose
    • cheap, renewable, easily available, under utilized resource
    • energy/fuel and suitable molecules which can replace petroleum products
  • Lignocellulose bioethanol production process
    • degradation of lignocellulose to fermentable sugars
    • fermentation of sugars to bioethanol
  • Optimum ethanol production bottle necked
    • suboptimal xylose utilization and release of microbial inhibitor molecules during biomass degradation

Fermentation

Pretreatment

Hydrolysis

overcoming inhibitor toxicity
Overcoming Inhibitor toxicity
  • Challenge – Release of inhibitor molecules during lignocellulose degradation
    • furans, phenolics and weak acids
    • severely impact yeast fermentation efficiency
  • Process Optimization
    • feedstock, pretreatment, hydrolysis conditions
    • fermentation strategies
  • Detoxification of hydrolysate
    • physical (evaporation); chemical (over-liming)
    • biological: microbial and enzymatic approaches
  • Shown detoxification costs can constitute 22% of total ethanol production cost (Ding et al., 2009)
    • economically limited
    • inhibitor specific and loss of fermentable sugars
overcoming inhibitor toxicity1
Overcoming Inhibitor toxicity
  • Sustainable cost effective bioethanol fermentation require “hardened” inhibitor resistant fermentation strains
  • Rational engineering approach
    • Genetic modification – yeast oxido-reductase detoxification genes
    • boost innate detoxification mechanisms of yeast
    • furfural, HMF, Formic acid
    • improved tolerance to specific inhibitor
  • Evolutionary engineering techniques
    • mutation and long term continuous cultures
    • simulate natural selection under selective pressure
hardening yeast
Hardening yeast
  • Despite on-going yeast hardening strategies
  • Inhibitor resistant fermentation strains remain elusive and highly sought after!!
  • Project aim : Generate “hardened” inhibitor resistant yeast strains
  • Approach which combine Novel rational metabolic engineering and evolutionary engineering
hardening yeast1
Hardening yeast
  • Strain generation - Rational metabolic engineering
    • industrial xylose utilization base strains
  • Identify and select yeast detoxification genes from literature
    • combine specific detoxification genes with cell membrane stress response genes
  • Express inhibitor resistance genes in Saccharomycescerevisiae
    • novel gene combinations
    • elucidate synergistic /antagonistic combinations
hardening yeast2
Hardening yeast
  • Evolutionary engineering
    • long term continuous cultures - bioreactor
    • selective pressure – increasing concentrations of inhibitors
    • further enhance inhibitor resistance
    • evaluate fermentation efficiency in toxic hydrolysate
  • Novel “HARDENED” inhibitor resistant strains
  • Optimization of lignocellulosic bioethanol production
acknowledgements
Acknowledgements

Supervisors: Prof J Gorgens and Prof WH Van Zyl

Department of process engineering

NRF - Financial Support

Thank You

slide11
Yeast Hardening for Cellulosic Ethanol production

Bianca A. Brandt

Supervisor: Prof J Gorgens

Co-Supervisor: Prof WH Van Zyl

Department of Process Engineering

University of Stellenbosch

Energy Postgraduate Conference 2013

introduction2
Introduction
  • Growing global move towards sustainable green energy production
    • Spurred by dependence on rapidly depleting Finite Fossil fuels
    • Various environmental and socio-economic concerns
  • Studies into Alternative Clean, Renewable and Sustainable energy resources:
    • solar-electric/thermal, hydroelectric, geothermal, tidal, wave, wind and ocean thermal power systems
    • furthermore, a great deal of work has gone into the development of bio-fuels
introduction3
Introduction
  • Why Biofuels?
    • Vehicular transportation- energy stored easier in form of combustible hydrocarbons then as electricity or heat
    • compatible with current distribution systems
    • Supplement and replace fossil fuels
  • A range of bio-fuels are currently being investigate
  • Bioethanol - benchmark biofuel
    • production based on a proven low cost technological platform
    • Brazil and USA -cost effective 1st generation bioethanol
    • Sugar and starch
  • 2nd generation bioethanol from lignocelluloses
cellulosic bioethanal
Cellulosic Bioethanal
  • Bioethanol from Lignocellulose
    • cheap, renewable, easily available, under utilized resource
    • energy/fuel and suitable molecules which can replace petroleum products
  • Lignocellulose bioethanol production process
    • degradation of lignocellulose to fermentable sugars
    • fermentation of sugars to bioethanol
  • Optimum ethanol production bottle necked
    • suboptimal xylose utilization and release of microbial inhibitor molecules during biomass degradation

Fermentation

Pretreatment

Hydrolysis

overcoming inhibitor toxicity2
Overcoming inhibitor toxicity
  • Challenge – Release of inhibitor molecules during lignocellulose degradation
    • furans, phenolics and weak acids
    • severely impact yeast fermentation efficiency
  • Process Optimization
    • feedstock, pretreatment, hydrolysis conditions
    • fermentation strategies
  • Detoxification of hydrolysate
    • physical (evaporation); chemical (over-liming)
    • biological: microbial and enzymatic approaches
  • Shown detoxification costs can constitute 22% of total ethanol production cost (Ding et al., 2009)
    • economically limited
    • inhibitor specific and loss of fermentable sugars
overcoming inhibitor toxicity3
Overcoming inhibitor toxicity
  • Sustainable cost effective bioethanol fermentation require “hardened” inhibitor resistant fermentation strains
  • Rational engineering approach
    • Genetic modification – yeast oxido-reductase detoxification genes
    • boost innate detoxification mechanisms of yeast
    • furfural, HMF, Formic acid
    • improved tolerance to specific inhibitor
  • Evolutionary engineering techniques
    • mutation and long term continuous cultures
    • simulate natural selection under selective pressure
hardening yeast3
Hardening yeast
  • Despite on-going yeast hardening strategies
  • Inhibitor resistant fermentation strains remain elusive and highly sought after!!
  • Project aim : Generate “hardened” inhibitor resistant yeast strains
  • Approach which combine Novel rational metabolic engineering and evolutionary engineering
hardening yeast4
Hardening yeast
  • Strain generation - Rational metabolic engineering
    • Industrial xylose utilization base strains
  • Identify and select yeast detoxification genes from literature
    • Combine specific detoxification genes with cell membrane stress response genes
  • Express inhibitor resistance genes in Saccharomyces cerevisiae
    • novel gene combinations
    • elucidate synergistic /antagonistic combinations
hardening yeast5
Hardening yeast
  • Evolutionary engineering
    • long term continuous cultures - bioreactor
    • selective pressure – increasing concentrations of inhibitors
    • further enhance inhibitor resistance
    • evaluate fermentation efficiency in toxic hydrolysate
  • Novel “HARDENED”inhibitor resistant strains
  • Optimization of lignocellulosic bioethanol production
acknowledgements1
Acknowledgements

Supervisors: Prof J Gorgens and Prof WH Van Zyl

Department of process engineering

NRF - Financial Support

Thank You

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