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Growth & Culture of Bacteria

Growth & Culture of Bacteria. Binary Division. 1 to 2 to 4 to 8 to ?. Phases of Growth. Lag Adapt to nutrients Log Active growth Stationary Death = Growth rate Death Nutrients consumed pH too low (why?) Optimize curves in production. Log Growth. Measuring Growth. Direct Counts

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Growth & Culture of Bacteria

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  1. Growth & Culture of Bacteria

  2. Binary Division • 1 to 2 to 4 to 8 to ? Chapter 6

  3. Phases of Growth • Lag • Adapt to nutrients • Log • Active growth • Stationary • Death = Growth rate • Death • Nutrients consumed • pH too low (why?) • Optimize curves in production Chapter 6

  4. Log Growth Chapter 6

  5. Chapter 6

  6. Chapter 6

  7. Measuring Growth • Direct Counts • Petroff-Hauser Chamber • Pro’s vs. Con’s • Serial Dilution • 10-fold serial dilutions • Pro’s vs. Con’s • MPN (Most Probable Number) • Put 10, 1, and 0.1 ml into 10-mls broth • Repeat 5 times per volume • Statistical accurate sampling • Public Health Standards are written for MPN Chapter 6

  8. Chapter 6

  9. Chapter 6

  10. Chapter 6

  11. Chapter 6

  12. Measuring Growth-cont’d Turbidity Spectrophotometer Scale %Transmittance Optical Density or Absorbance Filtration 0.45 - 0.2 um sizes Grid Pattern on Filter Standards for Public Health 0 E.coli / 100 ml of water Also used for sterilization Chapter 6

  13. Chapter 6

  14. Chapter 6

  15. Physical Factors: -philes • pH • Acido-, Neutro-, Alkaliphiles • Canned foods-Hot Pack vs. Pressure Cooking • High Acids- tomatoes • Neutro-corn, beans, meat • Temperature • Psychro-, Meso- Thermophiles • Growth Curve • Problems Chapter 6

  16. Chapter 6

  17. Note the drop-off as you get closer to the Optimum! Chapter 6

  18. What effect would have a fever have on Mesophiles?? Chapter 6

  19. Temperature Problems • Thermophiles • Hot tubs-public • Heat Resistant Enzymes in PCR • Psychrophiles • Cold food (growth in transit) • Listeria grows in hot dogs Chapter 6

  20. Salt Concentration • Halophiles • Great Salt Lake • Salt Pork Chapter 6

  21. Chapter 6

  22. Physical Factors: cont’d • Moisture • Beef Jerky • Lyophilization (Freeze Dry) • Oxygen • Aerboes vs. Anaerobes + ------ + ---------- • Osmotic Pressure • Pseudomonas grows in distilled water • Jelly- Jams (high sugar) • Salt Pork (high salt) Chapter 6

  23. Nutritional Factors • Carbon Source • Auto- or Hetero- • CO2 or Organic compounds • Nitrogen Source • NO3- ==> NO2 ==> NH3 to Amino Acids ==> Proteins • Sulfur • Phosphorus • Trace Elements • Fe, some required • Host Sideophores bind Fe Chapter 6

  24. More -trophs • Auxotrophs • Can live on simple compounds • NO3-, Glucose • Make all Amino Acids, Vitamins, etc. • Prototrophs • Require complex compounds • Vitamins, Amino Acids • Fastidious • Most Pathogens Chapter 6

  25. Types of Media • Complex Medium • Peptones, Yeast Extract • Fastidious • Prototrophs • Synthetic Medium • Minimal Media • Auxotrophs Chapter 6

  26. Exoenzymes • Secreted into environment • Catabolize food products • Protease, DNAase, Amylase, Lipase • Used in identification Chapter 6

  27. Chapter 6

  28. Oxygen Requirments • Classification • Aerobic • Anaerobic • Falcultative Anaerobic • Microaerophilic • Outline for Topic • Media • Cultivation • Oxygen Toxicity Chapter 6

  29. Flluid Thioglycollate Medium (FTM) • Peptones, Yeast Extracts, Glucose • Thioglycollate-binds O2 • Agar-slow diffusion of O2 • Rezaruin- O2 indicator Chapter 6

  30. FTM Media Chapter 6

  31. Growth Chambers • Candle Jars • Microaerophillic • Gas-Paks • Anaerobes & Faculatative Anaerobes Chapter 6

  32. Chapter 6

  33. Why Anerobes vs. Aerobes • O2 is reactive-toxic (binds e-’s) • Requires 4 e-’s to form water • Intermediates are Free Radicals • Free Radicals steal e-’s • Oxidization of compounds • Loss of energy from compounds • DNA molecule breaks Chapter 6

  34. Chapter 6

  35. Chapter 6

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