1 / 20

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.

slayden
Télécharger la présentation

Yeast Hardening for Cellulosic Ethanol production

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. 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

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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

  8. 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

  9. 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

  10. Acknowledgements Supervisors: Prof J Gorgens and Prof WH Van Zyl Department of process engineering NRF - Financial Support Thank You

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. 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

  20. Acknowledgements Supervisors: Prof J Gorgens and Prof WH Van Zyl Department of process engineering NRF - Financial Support Thank You

More Related