4 5-microbial nutrition and culture (2)


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4 5-microbial nutrition and culture (2)

  1. 1. Metabolism cont’d<br />
  2. 2. Carbohydrate Catabolism<br />
  3. 3. Carbohydrate Catabolism cont’d<br />
  4. 4. Summary of Carbohydrate Catabolism<br />
  5. 5. TCA Cycle (Krebs Cycle)<br />2acetyl-CoA groups are oxidized in the Krebs cycle for each glucose molecule (1 six-carbon glucose is oxidized to two 3 carbon pyruvic acid molecules, each of which is decarboxylated to produce an acetyl-CoA molecule). <br />Electrons are picked up by NAD+ and FAD for the electron transport chain.<br />From one molecule of glucose, oxidation in the Krebs cycle produces 6 molecules of NADH, 2 molecules of FADH2, and 2 molecules of ATP.<br />Decarboxylation produces 6 molecules of CO2.<br />
  6. 6. TCA Cycle (Krebs Cycle)<br />
  7. 7. Electron Transport Chain<br />As electrons are passed from carrier to carrier in the chain, they decrease in energy and some of the energy lost is harnessed to make ATP<br />
  8. 8. Summary<br />In aerobic prokaryotes, 38 ATP molecules can be produced form complete oxidation of a glucose molecule in glycolysis, the Krebs cycle, and the electron transport chain.<br /> <br />In eukaryotes, 36 or 38 ATP molecules are produced from complete oxidation of a glucose molecule (in some tissues 2 ATP are required to shuttle the 2 electrons from the NADH produced in glycolysis across the mitochondrial membrane to the electron transport chain, in others there is no energy cost and 38 ATP are gained per mole of glucose).<br />
  9. 9. Summary of Respiration<br />Aerobic respiration: The final electron acceptor in the electron transport chain is molecular oxygen O2<br />Anaerobic respiration: The final electron acceptor in the electron transport chain is not O2. Yields less energy than aerobic respiration because only part of the Krebs cycle operates under anaerobic condition<br />
  10. 10. Anaerobic Respiration<br />Electron acceptors other than oxygen are used i.e.:<br />Inorganic oxygen containing molecules such as Nitrate (NO3-), Sulfate (SO42-), Ferric iron (FE3+), Carbonate (CO32-) and Perchlorate (ClO4-)<br />Less energy is released<br />Permits microorganisms to respire in anoxic environments<br />
  11. 11. Fermentation<br />Any spoilage of food by microorganisms (general use)<br />Any process that produces alcoholic beverages or acidic dairy products (general use)<br />Any large scale microbial process occurring with or without air (common definition used in industry)<br />
  12. 12. Fermentation cont’d<br />Scientific definition<br />Release of energy from organic molecules<br />Does not require oxygen<br />Does not use the Krebs cycle of Electron transport chain<br />Uses organic molecule as the final electron acceptor<br />
  13. 13.
  14. 14. Types of Fermentation<br />
  15. 15.
  16. 16. Fermentations By Naturally-Occurring Organisms<br />
  17. 17. Fermentations By Genetically Engineered Organisms<br />
  18. 18. Fermentation<br />Alcohol fermentation: Produces ethanol and CO2<br />Lactic acid fermentation: Produces lactic acid<br /> -homolactic fermentation: Produces lactic acid only<br /> -heterolactic fermentation: Produces lactic acid and other compounds<br />
  19. 19. Final Electron Acceptor<br />Electron<br />Electron carriers<br />Final electron acceptor<br />