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Ethanol Production

Ethanol Production. Feedstock. Biomass Starch. Definitions. Biomass. the relatively large amounts of heterogeneous matter produced by living organisms. It includes residues originating from plants, animals, and microorganisms. Lignocellulosic biomass.

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Ethanol Production

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  1. Ethanol Production

  2. Feedstock • Biomass • Starch

  3. Definitions Biomass the relatively large amounts of heterogeneous matter produced by living organisms. It includes residues originating from plants, animals, and microorganisms Lignocellulosic biomass Biomaterials whose composition is dominated by lignified cell walls from vegetative plants.

  4. Polysaccharide and lignin content of representative lignocellulosic feedstocks a,b avalues are percentages on a dry weight basis b data taken from Puls and Schuseil (1992) c measured as Klason lignin

  5. Biomass (cellulose, Hemicellulose, lignin) Mechanical chipping/grinding Milled Biomass Pretreatment (Dilute acid, 180oC) Pretreated solid (cellulose, lignin) Prehydrolysate Liquid (xylose, 2-furaldehyde) Enzymatic saccharification (fungal cellulases) Fermentation Ethanol Hydrolysate Liquid (glucose) Hydrolyzed Solid (lignin) fermentation Ethanol

  6. Chemical Composition of Corn (percent of dry matter) aplus lignin bas xylose cas glucose

  7. Corn Wet Milling Clean Corn Steeps Steep water (6.5%) Losses (1%) Germ System Germ (8%) Mill and Screen System Fiber (10.2%) Centrifugal Separator Gluten (6.3%) Prime Starch (68%) Wash Adapter from C.R. Keim, 1999

  8. Enzymatic Starch Conversion Starch Slurry -amylase Liquefaction Maltodextrin Glucoamylase/ Pullulanase Saccharification To Fuel Ethanol Maltose Syrups Purification Glucose Syrups Mixed Syrups Glucose Isomerase Isomerization Fructose Syrups Refining Adapter from H.S. Olsen, 1995

  9. Feeder Pathways for Glycolysis

  10. Entry of Fructose into Glycolysis

  11. Fate of Pyruvate • Lactate dehydrogenase • during exercise • Reversible in liver • Location: cytoplasm • Pyruvate dehydrogenase • Source of AcetylCoA • Irreversible reaction • Location: Mitochondria • Ethanol synthesis • In yeast, some bacteria • Location cytoplasm

  12. Reduction of pyruvate to ethanol (microorganism) • It occurs by the 2 reactions shown below: • The overall reaction of alcohol fermentation: • Glc+2ADP +2P---------> 2 Ethanol + 2CO2 + 2ATP + 2 H2O

  13. Pyruvate decarboxylase mechanism

  14. There is no net oxidation-reduction in the conversion of Glc into Ethanol, NAD+ is used first and made it later!

  15. Active site of Alcohol dehydrogenase

  16. Pyruvate decarboxylase is present in brewer’s and baker’s yeast. CO2 produced during alcohol fermentation is responsible for the characteristic carbonation of champagne. • In baking, CO2 fermentation by pyruvate decarboxylase during fermentation of dough due to CO2 , dough rises. • Alcohol dehydrogenase metabolizes alcohol. • TPP carries “active aldehyde” groups • The pyruvate decarboxylase reaction is the first reaction we see that TPP is involved. TPP------> Vit B1. If B1 is not enough

  17. More about TPP • TPP plays an important role in the cleavage of bonds adjacent to a carbonyl group such as the decarboxylation of alpha-ketoacids and in chemical rearrangements involving transfer of an activated aldehyde group from one C to another. • The functional part of TPP is the thiazolium ring. The proton at C-2 of the ring is relatively acidic, loss of this proton, produces an active site in TPP. • TPP is involved in the following reactions • 1. Pyruvate decarboxylase • 2. Pyruvate dehydrogenase • 3. Alpha-Ketoglutaratedehyrogenase • 4. Transketolase

  18. Microbial fermentation yield other end products of commercial value: • Lactate and ethanol are the common products of microbial fermentation • Clostridium acetobutyricum, ferments starch to butanol and acetone. • Here comes industrial fermentation, purpose is to make important products from readily available material (like starch) by using microorganism.

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