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Microbial Growth

Microbial Growth. Binary Fission Growth Rate Generation Time E. coli can double every 20 minutes Many Bacteria have 1-3 hr Generation Times. Growth Curve. Lag Phase Log Phase (Exponential) Stationary Phase Death Phase Cryptic Growth. Measuring Bacterial Growth. Total Cell Counts

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Microbial Growth

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  1. Microbial Growth • Binary Fission • Growth Rate • Generation Time • E. coli can double every 20 minutes • Many Bacteria have 1-3 hr Generation Times

  2. Growth Curve • Lag Phase • Log Phase (Exponential) • Stationary Phase • Death Phase • Cryptic Growth

  3. Measuring Bacterial Growth • Total Cell Counts • Direct Microscopic Counts • Petroff-Hauser Counting Chambers

  4. Viable Counts • Plate Counts • Spread Plate – Sample Spread on Solid Agar Plates

  5. Pour Plate • Dilute Sample Suspended into Melted Agar

  6. Dilution

  7. Extinction Dilution • MPN – Most Probable Number

  8. Turbidity Measurement • Spectrophotometer

  9. Culture Type • Batch Culture • Continuous Culture • Chemostat

  10. Controlling Growth • Temperature • Minimum • Optimal • Maximum

  11. Temperature Ranges

  12. Cold Temperatures • Psychrophile • Psychrotolerant • Freezing • Preserves Bacterial Cultures

  13. Other Factors pH Low pH Used to Preserve Foods Acidophiles Alkaliphiles Buffers Used in Many Bacteriological Media

  14. Water Availability • Drying Limits Bacterial Growth • Halophiles • Osmophiles • Xerophiles

  15. Oxygen • Aerobe • Anaerobes • Facultative • Microaerophile

  16. Growth Word List Growth Curve Lag Phase, Exponential (log) Phase, Stationary Phase, Death Phase, Cryptic Growth Measuring Growth Total Cell Counts Direct Microscopic Counts Petroff-Hausser Counting Chambers Bacterial Growth Binary fission Growth rate Generation Time Exponential Growth Batch Culture

  17. Growth Word List 2 Controlling Growth Temperature Minimum, Optimal, Maximum Psychrophile (psychrotolerant) Mesophile, Thermophile Viable Count Plate Counts Spread Plate Pour Plate Dilution Extinction Dilution MPN – Most Probable Number Turbidity Measurements Continuous Culture Chemostat

  18. Growth Word List 3 Halophiles Osmophiles Xerophiles Oxygen Aerobes, Anaerobes Facultative Microaerophile Hyperthermophile Freezing pH Acidophile Alkaliphile Buffers Water Activity

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