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 Direct Microscopic Counts Petroff-Hauser Counting Chambers

Viable Counts Plate Counts Spread Plate – Sample Spread on Solid Agar Plates

Pour Plate Dilute Sample Suspended into Melted Agar

Dilution

Extinction Dilution MPN – Most Probable Number

Turbidity Measurement Spectrophotometer

Culture Type Batch Culture Continuous Culture Chemostat

Controlling Growth Temperature Minimum Optimal Maximum

Temperature Ranges

Cold Temperatures Psychrophile Psychrotolerant Freezing Preserves Bacterial Cultures

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

Water Availability Drying Limits Bacterial Growth Halophiles Osmophiles Xerophiles

Oxygen Aerobe Anaerobes Facultative Microaerophile

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

Growth Word List 2 Controlling Growth Viable Count 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

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