microbial growth
DESCRIPTION
Microbial Growth. Binary Fission Growth Rate Generation Time E. coli can double every 20 minutes Many Bacteria have 0.5-6 hr Generation Times. Cell Division. FTS proteins Divisome Division septum Default shape –Coccus MRE protein. Growth Curve. Batch Culture Lag Phase - PowerPoint PPT PresentationTRANSCRIPT
Microbial Growth
• Binary Fission• Growth Rate• Generation Time• E. coli can double
every 20 minutes• Many Bacteria have
0.5-6 hr Generation Times
Cell Division
• FTS proteins
• Divisome
• Division septum
• Default shape –Coccus
• MRE protein
Growth Curve
• Batch Culture• Lag Phase• Log Phase
(Exponential)• Stationary Phase• Death Phase• Cryptic Growth
Culture Type
• Batch Culture• Continuous Culture• Chemostat
Measuring Bacterial Growth
• Total Cell Counts• Direct Microscopic
Counts• Petroff-Hauser
Counting Chambers• DAPI• Flow Cytometer
Viable Counts
• Plate Counts• Spread Plate – Sample Spread on Solid Agar Plates• CFU – colony forming units
Pour Plate
• Dilute Sample Suspended into Melted Agar
Dilution
30-300 CFU –countable?
Extinction Dilution
• MPN – Most Probable Number
Turbidity Measurement
• Spectrophotometer
Controlling Growth
• Temperature• Minimum• Optimal• Maximum
Temperature Ranges
Cold Temperatures
• Psychrophile• Psychrotolerant• Freezing • Preserves Bacterial
Cultures• 15 C Optimal • Maximum 20 C
Thermophiles
• Thermophile
• Optimal 45 C+
• Hyperthermophile
• Optimal 80 C+
• Bacteria 95 C
• Archaea 100 C+
• Hot Springs
Other Factors
• pH• Low pH Used to
Preserve Foods• Acidophiles• Alkaliphiles• Buffers Used in Many
Bacteriological Media
(Proteins or PO4)
•Water Availability•Drying Limits Bacterial Growth•Halophiles•Osmophiles•Xerophiles
Oxygen
• Aerobe• Anaerobes• Obligate vs.
Facultative• Microaerophile
Growing AnaerobesAerotolerant vs. Obligate
Growth Word List
Bacterial Growth
Binary fission
Growth rate
Generation Time
Exponential Growth
Batch Culture
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
Growth Word List 2
Viable Count
Plate Counts
Spread Plate
Pour Plate
Dilution
Extinction Dilution
MPN – Most Probable Number
Turbidity Measurements
Continuous Culture
Chemostat
Controlling Growth
Temperature
Minimum, Optimal, Maximum
Psychrophile (psychrotolerant)
Mesophile, Thermophile
Growth Word List 3
Hyperthermophile
Freezing
pH
Acidophile
Alkaliphile
Buffers
Water Activity
Halophiles
Osmophiles
Xerophiles
Oxygen
Aerobes, Anaerobes
Facultative
Microaerophile