Bacterial Growth & Conditions
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Growth & Culture of Bacteria
Binary Division • 1 to 2 to 4 to 8 to ?
Chapter 6
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
Log Growth
Chapter 6
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
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
Chapter 6
Note the drop-off as you get closer to the Optimum!
Chapter 6
What effect would have a fever have on Mesophiles??
Chapter 6
Temperature Problems • Thermophiles – Hot tubs-public – Heat Resistant Enzymes in PCR
• Psychrophiles – Cold food (growth in transit) – Listeria grows in hot dogs
Chapter 6
Salt Concentration • Halophiles – Great Salt Lake – Salt Pork
Chapter 6
Chapter 6
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
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
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
Types of Media • Complex Medium – Peptones, Yeast Extract – Fastidious – Prototrophs
• Synthetic Medium – Minimal Media – Auxotrophs
Chapter 6
Exoenzymes • • • •
Secreted into environment Catabolize food products Protease, DNAase, Amylase, Lipase Used in identification
Chapter 6
Chapter 6
Oxygen Requirments • Classification – – – –
Aerobic Anaerobic Falcultative Anaerobic Microaerophilic
• Outline for Topic – Media – Cultivation – Oxygen Toxicity Chapter 6
Flluid Thioglycollate Medium (FTM)
• Peptones, Yeast Extracts, Glucose • Thioglycollate-binds O2 • Agar-slow diffusion of O2 • Rezaruin- O2 indicator
Chapter 6
FTM Media
Chapter 6
Growth Chambers • Candle Jars – Microaerophillic – Gas-Paks – Anaerobes & Faculatative Anaerobes
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
Binary Division • 1 to 2 to 4 to 8 to ?
Chapter 6
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
Log Growth
Chapter 6
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
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
Chapter 6
Note the drop-off as you get closer to the Optimum!
Chapter 6
What effect would have a fever have on Mesophiles??
Chapter 6
Temperature Problems • Thermophiles – Hot tubs-public – Heat Resistant Enzymes in PCR
• Psychrophiles – Cold food (growth in transit) – Listeria grows in hot dogs
Chapter 6
Salt Concentration • Halophiles – Great Salt Lake – Salt Pork
Chapter 6
Chapter 6
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
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
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
Types of Media • Complex Medium – Peptones, Yeast Extract – Fastidious – Prototrophs
• Synthetic Medium – Minimal Media – Auxotrophs
Chapter 6
Exoenzymes • • • •
Secreted into environment Catabolize food products Protease, DNAase, Amylase, Lipase Used in identification
Chapter 6
Chapter 6
Oxygen Requirments • Classification – – – –
Aerobic Anaerobic Falcultative Anaerobic Microaerophilic
• Outline for Topic – Media – Cultivation – Oxygen Toxicity Chapter 6
Flluid Thioglycollate Medium (FTM)
• Peptones, Yeast Extracts, Glucose • Thioglycollate-binds O2 • Agar-slow diffusion of O2 • Rezaruin- O2 indicator
Chapter 6
FTM Media
Chapter 6
Growth Chambers • Candle Jars – Microaerophillic – Gas-Paks – Anaerobes & Faculatative Anaerobes
Chapter 6
Chapter 6
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
Chapter 6
Chapter 6
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