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vsv3 Presentation Transcript

  • 1. Dr. Alvin Fox Nutrition, Growth and Metabolism
  • 2. KEY TERMS Obligate aerobe Obligate anaerobe Aerotolerant anaerobe Facultative anaerobe Microaerophilic Siderophore Mesophile Thermophile Psychrophile Generation time Growth curve Glycolysis Fermentation Anaerobic respiration Aerobic respiration Tricarboxylic acid (TCA) cycle or Krebs cycle Oxidative phosphorylation Ubiquinone Glyoxylate pathway
  • 3. Bacterial requirements for growth
    • oxygen (or absence)
    • energy
    • nutrients
    • optimal temperature
    • optimal pH
  • 4. Obligate aerobes
    • grow in presence of oxygen
    • no fermentation
    • oxidative phosphorylation
  • 5. Obligate anaerobes
      • no oxidative phosphorylation
      • fermentation
      • killed by oxygen
      • lack certain enzymes:
        • superoxide dismutase
        • O 2 - +2H + H 2 O 2
        • catalase
          • H 2 O 2 H 2 0 + O 2
        • peroxidase
          • H 2 O 2 H 2 0 /NAD NADH
  • 6. Aerotolerant anaerobes
      • respire anaerobically
      • not killed by oxygen
  • 7. Facultative anaerobes
      • fermentation
      • aerobic respiration
      • survive in oxygen
  • 8. Microaerophilic bacteria
      • grow
        • low oxygen
      • killed
        • high oxygen
  • 9. Optimal growth temperature
    • Mesophiles:
      • human body temperature
        • pathogens
        • opportunists
    • pyschrophile
      • close to freezing
    • thermophile
      • close to boiling
  • 10. pH
    • Many grow best at neutral pH
    • Some can survive/grow
      • - acid
      • - alkali
  • 11. Nutrient Requirements
    • Carbon
    • Nitrogen
    • Phosphorus
    • Sulfur
    • Metal ions (e.g. iron)
  • 12. Siderophores (S) Fe 2+ / S Receptor Fe 2+ / S
  • 13. Measuring bacterial mass (live + dead) in liquid culture Turbidity (Cloudiness)
  • 14. Measuring viable bacteria colony Colony forming units
  • 15. Growth Curve COLONY FORMING UNITS TIME Lag Log Stationary Death
  • 16. Growth Curve TURBIDITY (cloudiness) TIME Lag Log Stationary Autolysis
  • 17. Generation time
    • time for bacterial mass to double
    • Example
    • 100 bacteria present at time 0
    • If generation time is 2 hr
    • After 8 hr mass = 100 x 2 4
  • 18. SUGAR CATABOLISM
    • Glycolysis
      • Embden Meyerhof Parnas Pathway
      • most bacteria
      • also animals and plants
  • 19. Other pathways for catabolizing sugars
    • Pentose phosphate pathway (hexose monophosphate shunt)
      • generates NADPH
      • common in plants and animals
    • Entner Doudoroff Pathway
      • a few bacterial species
  • 20. Glycolysis NAD NADH Glucose Pyruvate C6 C3 ADP ATP
  • 21. Fermentation Pyruvate (C3) NADH NAD Short chain alcohols , fatty acids (C2-C4)
  • 22. Anaerobic Respiration = Glycolysis + Fermentation NAD NADH NADH NAD ATP
  • 23. Krebs Cycle (C4-C6 intermediate compounds ) Pyruvate 3CO 2 (C3) NAD NADH NADH NAD Oxidative phosphorylation O 2 H 2 O ADP ATP (C1)
  • 24. Aerobic Respiration = Glycolysis + Krebs Cycle/oxidative phosphorylation
    • Pyruvate to CO 2
        • NAD to NADH
        • glycolysis
        • Krebs cycle
    • Oxidative phosphorylation
      • NADH to NAD
      • ADP to ATP
  • 25. Oxidative phosphylation
      • converts O 2 to H 2 0 (oxidative)
      • converts ADP to ATP (phosphorylation)
      • electron transport chain
      • ubiquinones/cytochrome intermediates
  • 26. The Krebs cycle Citrate Isocitrate Alpha-keto glutarate Succinate Fumarate Malate Oxaloacetate Pyruvate -CO 2 Acetate + -CO 2 NADH -CO 2 NADH C2 C C C4 X x C6
  • 27. Krebs Cycle - sugar as sole carbon source Pyruvate Acetate -CO 2 C4 Pyruvate + CO 2 + Citrate C C3 Oxalo acetate Oxaloacetate -2CO 2 Aspartic acid Krebs cycle ENERGY STORAGE BIOSYNTHESIS C3 C C2 C6 C4 Oxalo acetate X
  • 28. Krebs Cycle – fatty acids as sole carbon source Fatty acids Acetate + Citrate Oxalo acetate -2CO 2 Aspartic acid Krebs cycle ENERGY BIOSYNTHESIS Isocitrate Succinate Glyoxylate + Acetate + Malate Oxalo acetate x C4 C2 C2 C4 C6 -2CO 2
  • 29. The Glyoxylate and Krebs cycles Citrate Isocitrate Alpha-keto glutarate Succinate Fumarate Glyoxylate Acetate Malate Oxaloacetate 1 2
  • 30.
            • Krebs Cycle
          • biosynthetic
          • energy storage
    • Removal of intermediates
          • must be replenished
    • Unique enzymatic replenishment pathways
      • sugars
      • fatty acids