vsv3
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This document summarizes key concepts in bacterial nutrition, growth, and metabolism. It discusses the different types of bacteria based on their oxygen requirements, including obligate aerobes, obligate anaerobes, aerotolerant anaerobes, and facultative anaerobes. It also covers optimal growth temperatures, pH requirements, nutrient needs, and pathways like glycolysis, fermentation, the Krebs cycle, and oxidative phosphorylation. Measurement techniques for bacterial growth like turbidity and colony forming units are also summarized.
vsv3
- 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