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  • Specific Yeasts Developed for Modern Ethanol Production

    Mike KnaufEthanol Technology

    25 April 2006

    2nd Bioethanol Technology MeetingDetmold, Germany

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Presentation Outline

    Start with the Alcohol Production Fermentor

    Yeast Strains

    Yeast Product Formulations

    Yeast Management Options

    Commercial Yeast Production, Quality Control,

    Technical Support

    Summary & Conclusions

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Start with the Alcohol Production FermentorThis is where the yeast does its work!This is where the yeast does its work!

    What are YOUR Objectives?Check one:

    Efficiency (or Yield)ThroughputConsistency

    Choose & Prioritize: Process control Minimal contamination Fast fermentation Complete fermentation Minimal input costs Foolproof/Automate

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Process Design Considerations

    Fermentation:A. Continuous (e.g., cascade)B. Batch

    Yeast Management:1. Propagation (yeast biomass

    production) Batch Continuous

    2. Conditioning (metabolic acclimitization)

    3. Rehydration4. Direct Pitch

    Com

    plex

    ity

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Metabolic Pathways

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    From: Pretorius, 2000, Boulton et al., 1996

    Glycolysis: The degradation of sugar to alcohol with production of energy (ATP) for cell growth.

    End products

    Substrates

    12 Enzymes convert ~90% of available glucose to ethanol and CO2 under conditions of controlled oxidation/reduction balance.

    Thousands of other enzymes are also located in the cell.

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    What Is a Yeast Strain?Species:A fundamental category of taxonomic classification consisting of organisms capable of interbreeding.

    600+ species of yeast identified in natureSaccharomyces cerevisiae most significant

    Strain:A group of organisms of the same species having distinctive characteristics.

    Unlimited number of strains possibleThousands of yeast strains already selected

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    The Big Picture

    EnvironmentGenotype Phenotype

    Production MethodProduct FormPlant Handling

    Inoculation TechniqueFermentation Conditions

    Strain Characteristics Fermentation Performance

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Strains: Saccharomyces cerevisiae

    EngineeredEngineered

    Selected Selected IIII

    Selected Selected II

    WildWild

    TimeTime

    Per

    form

    ance

    Per

    form

    ance

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Strain Selection and AttributesStrain Selection and Development Techniques

    Isolation from fermentationsScreening from culture collectionsMutation and selectionBreeding (hybridization)Spheroplast fusionCloning

    How do Strains Differ?Temperature, pH, sugar, and alcohol toleranceFlocculation and foam productionRespiratory growth rate, yield, and stabilityKiller factor and killer resistanceEnzyme activity and carbohydrate utilization

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Strain Comparison in a Maize Mash Fermentation

    0

    2

    4

    6

    8

    10

    12

    14

    16

    18

    0 20 40 60

    Time, h

    EtO

    H C

    once

    ntra

    tion

    (%, v

    /v)

    .

    Zhang 2005

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Fermentation Conditions

    Dose Rate

    Nutrition

    Stress

    Contamination

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Dose Rate: Effect on Performance

    Zhang 2005 (2)

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Nutrition

    For optimal fermentation, yeast require:

    Substrates (C, N, P, S) in optimal ratios

    Minerals (K, Na, Mg, Ca, Zn, Fe, Mn, Cu, Co, etc)

    Vitamins (B1, B5, B6, Biotin, etc)

    Oxygen (for production of unsaturated fatty acids)

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Free Amino Nitrogen (mg/L mash @ 22% solids)

    Available from fermentation feedstock

    Thomas, Ingledew

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Stress

    Ingledew 2003

    Contamination

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Commercial Yeast Products

    Formulations & PerformanceADY = Active Dry YeastFresh Cake YeastLiquid Yeast (2)

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Performance: Active Dry YeastAcceptable Fermentation Performance

    Good viabilityNeed for rehydrationAcclimitization often recommended

    Storage and HandlingRefrigerated storage not requiredTypically 2 year shelf lifeObvious choice for irregular order patternsLowest cost storageMust handle solid product in bags or boxes

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Performance: Fresh Cake Yeast

    Excellent Fermentation PerformanceHigh viabilityNo need for rehydrationMinimal acclimitization requirement

    Storage and HandlingLimited Shelf-LifeSealed, Refrigerated: Stable for at least 6 weeks Must handle solid product in bags or boxes

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Dry vs Fresh Cake Yeast, Grain Mash Fermentation

    0

    1

    2

    3

    4

    5

    6

    7

    0,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0

    Time (h)

    EtO

    HC

    once

    ntra

    tion

    (v/v

    )

    ADY Fresh Cake

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Performance: Fresh Liquid YeastSuperior Fermentation Performance

    Highest viabilityNo need for rehydrationAcclimitization not required

    Storage and HandlingPoor ambient temperature storage stabilityRefrigerated, unstabilized: Shelf life = 1-2 weeks MAXRefrigerated, stabilized: 3+ month shelf life demonstratedAdditional handling and cost for refrigerationLiquid product amenable to automated addition through DCS (Distributed Control System)

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Form Comparison

    Active Dry YeastOptimized for stabilityDoes not require refrigerationGood for intermittent useGood for small volume strains

    Fresh Cake YeastOptimized for activityDoes not require rehydrationShorter lag phase in fermentorGood for difficult to dry strainsAvailability

    Stabilized Liquid YeastBetter stability than fresh yeastHigher activity than fresh or dryAmenable to automated dosingSuitable for direct pitch to fermentorAvailability

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast Management

    Options1. Propagation (yeast

    biomass production) Continuous Batch

    2. Conditioning (metabolic acclimitization)

    3. Rehydration4. Direct Pitch

    ObjectiveTo supply to the Fermentor yeast

    with the following properties:Adequate numbersHigh ViabilityHigh VitalityLow ContaminationIn Log growthAt the correct time in fermentation

  • AN INTRODUCTION TO ETHANOL TECHNOLOGYAN INTRODUCTION TO ETHANOL TECHNOLOGYYeasts for Modern Ethanol ProductionYeasts for Modern Ethanol Production

    Yeast PropagationLesson #1: InLesson #1: In--Plant Yeast Propagation is NEVER Plant Yeast Propagation is NEVER Completely Successful!!Completely Successful!!

    Typical Goals: Increase yeast cell numbers: 2-4X CFU/m

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