Copyright © 2010 Pearson Education, Inc.
Metabolism and Growth
Copyright © 2010 Pearson Education, Inc.
Requirements for Growth: chemical
 NOT COPS
 N
 Organic growth factors
 Trace...
Copyright © 2010 Pearson Education, Inc.
What is the function of carbon,
nitrogen, sulfur, phosphorus and trace
elements?
Copyright © 2010 Pearson Education, Inc.
Chemical Requirements
 Carbon
 Structural organic molecules, energy source
 Ch...
Copyright © 2010 Pearson Education, Inc.
Chemical Requirements
 Nitrogen
 In amino acids and proteins
 Most bacteria de...
Copyright © 2010 Pearson Education, Inc.
Chemical Requirements
 Sulfur
 In BAT: Biotin, amino acids, and protein
 Phosp...
Copyright © 2010 Pearson Education, Inc.
Chemical Requirements
 Trace elements
 Inorganic elements required in small amo...
Copyright © 2010 Pearson Education, Inc. Table 6.1
The Effect of Oxygen (O2) on Growth
Copyright © 2010 Pearson Education, Inc.
Organic Growth Factors
 Where are organic growth factors obtained?
 from the en...
Copyright © 2010 Pearson Education, Inc.
Catabolic and Anabolic Reactions
 Metabolism: The sum of the chemical reactions ...
Copyright © 2010 Pearson Education, Inc.
Catabolic and Anabolic Reactions
 A metabolic pathway is a sequence of
enzymatic...
Copyright © 2010 Pearson Education, Inc.
Enzymes
 Proteins
 Biological catalysts
 Produced by living cells
 Catalyze c...
Copyright © 2010 Pearson Education, Inc.
Enzyme Components
 Biological catalysts
 Speed up a chemical reaction without b...
Copyright © 2010 Pearson Education, Inc.
Factors influencing Enzymatic Activity
 Temperature
 pH
 Substrate concentrati...
Copyright © 2010 Pearson Education, Inc.
Inhibitors
Function: control bacteria by control of enzymes
 Competitive – compe...
Copyright © 2010 Pearson Education, Inc.
Carbohydrate Catabolism
 The breakdown of carbohydrates to release energy
 Gluc...
Copyright © 2010 Pearson Education, Inc.
Carbohydrate Catabolism
 Glycolysis: glucose broken down
 Leads into cellular r...
Copyright © 2010 Pearson Education, Inc.
Metabolic Diversity among Organisms
 Photoautotrophs
 Photoheterotrophs
 Chemo...
Copyright © 2010 Pearson Education, Inc.
The Requirements for Growth: Physical
 Physical requirements
 Temperature
 pH
...
Copyright © 2010 Pearson Education, Inc.
Physical Requirements
 Temperature
 Minimum growth temperature
 Optimum growth...
Copyright © 2010 Pearson Education, Inc.
Temperature
 Three primary Groups
1.Psychrophiles – cold loving
2.Mesophiles – m...
Copyright © 2010 Pearson Education, Inc. Figure 6.1
Typical Growth Rates and Temperature
Copyright © 2010 Pearson Education, Inc.
Psychrotrophs
 Grow between 0°C and 20–30°C
 Cause food spoilage
Copyright © 2010 Pearson Education, Inc. Figure 6.2
Food Preservation Temperatures
Copyright © 2010 Pearson Education, Inc.
pH
 Most bacteria grow between pH 6.5 and 7.5
 Molds and yeasts grow between pH...
Copyright © 2010 Pearson Education, Inc. Figure 6.5
Biofilms
 Microbial communities
 Form slime or
hydrogels
 Form on t...
Copyright © 2010 Pearson Education, Inc. Applications of Microbiology, p. 57
Biofilms
 Share nutrients
 Sheltered from
h...
Copyright © 2010 Pearson Education, Inc.
Agar
 Complex polysaccharide
 Used as solidifying agent for culture media in Pe...
Copyright © 2010 Pearson Education, Inc.
Culture Media
 Chemically defined media: Exact chemical
composition is known
 C...
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Copyright © 2010 Pearson Education, Inc.
Anaerobic Culture Methods
 Reducing media
 Contain chemicals (thioglycolate or ...
Copyright © 2010 Pearson Education, Inc. Figure 6.7
An Anaerobic Chamber
Copyright © 2010 Pearson Education, Inc. Figure 6.10
Selective Media
 Suppress unwanted microbes and encourage
desired mi...
Copyright © 2010 Pearson Education, Inc. Figure 6.9
Differential Media
 Make it easy to distinguish colonies of different...
Copyright © 2010 Pearson Education, Inc. Figure 6.11
The Streak Plate Method
Copyright © 2010 Pearson Education, Inc.
Preserving Bacterial Cultures
 Deep-freezing: –50° to –95°C
 Lyophilization (fr...
Copyright © 2010 Pearson Education, Inc.
Measuring Microbial Growth
Direct Methods
 Plate counts
 Filtration
 MPN
 Dir...
Copyright © 2010 Pearson Education, Inc.
 Standard plate count
 Viable count
 Microscopic count
 No incubation time
 ...
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2 - Metabolism and Growth

  1. 1. Copyright © 2010 Pearson Education, Inc. Metabolism and Growth
  2. 2. Copyright © 2010 Pearson Education, Inc. Requirements for Growth: chemical  NOT COPS  N  Organic growth factors  Trace elements  C  O  P  S
  3. 3. Copyright © 2010 Pearson Education, Inc. What is the function of carbon, nitrogen, sulfur, phosphorus and trace elements?
  4. 4. Copyright © 2010 Pearson Education, Inc. Chemical Requirements  Carbon  Structural organic molecules, energy source  Chemoheterotrophs use organic carbon sources  Autotrophs use CO2
  5. 5. Copyright © 2010 Pearson Education, Inc. Chemical Requirements  Nitrogen  In amino acids and proteins  Most bacteria decompose proteins  Some bacteria use NH4+ or NO3–  A few bacteria use N2 in nitrogen fixation
  6. 6. Copyright © 2010 Pearson Education, Inc. Chemical Requirements  Sulfur  In BAT: Biotin, amino acids, and protein  Phosphorus  In DNA, RNA, ATP, and membranes
  7. 7. Copyright © 2010 Pearson Education, Inc. Chemical Requirements  Trace elements  Inorganic elements required in small amounts  Usually as enzyme cofactors
  8. 8. Copyright © 2010 Pearson Education, Inc. Table 6.1 The Effect of Oxygen (O2) on Growth
  9. 9. Copyright © 2010 Pearson Education, Inc. Organic Growth Factors  Where are organic growth factors obtained?  from the environment  What are organic growth factors involved with?  Vitamins, amino acids, purines, and pyrimidines
  10. 10. Copyright © 2010 Pearson Education, Inc. Catabolic and Anabolic Reactions  Metabolism: The sum of the chemical reactions in an organism  catabolism, require water: cells break down sugars  anabolism, dehydration synthesis: formation of proteins from amino acids
  11. 11. Copyright © 2010 Pearson Education, Inc. Catabolic and Anabolic Reactions  A metabolic pathway is a sequence of enzymatically catalyzed chemical reactions in a cell  A - B, B - C, C - D  A cannot make D  Metabolic pathways are determined by enzymes  Enzymes are encoded by genes
  12. 12. Copyright © 2010 Pearson Education, Inc. Enzymes  Proteins  Biological catalysts  Produced by living cells  Catalyze chemical reactions by lowering activation energy  Speed up a chemical reaction without being permanently altered
  13. 13. Copyright © 2010 Pearson Education, Inc. Enzyme Components  Biological catalysts  Speed up a chemical reaction without being altered  Are specific (active site) – act on specific substance (substrate)  Crucial function: speed up biochemical reactions at a temp which is compatible with a living, normal functioning cell
  14. 14. Copyright © 2010 Pearson Education, Inc. Factors influencing Enzymatic Activity  Temperature  pH  Substrate concentration  Inhibitors
  15. 15. Copyright © 2010 Pearson Education, Inc. Inhibitors Function: control bacteria by control of enzymes  Competitive – compete with the normal substrate for the active site  shape and chemical structure are similar to normal substrate  Ex. Sulfa drug  Noncompetitive – interact with another part of the enzyme, changes shape = nonfunctional
  16. 16. Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism  The breakdown of carbohydrates to release energy  Glucose most commonly used carbohydrate  Glycolysis: breaking down glucose to pyruvic acid
  17. 17. Copyright © 2010 Pearson Education, Inc. Carbohydrate Catabolism  Glycolysis: glucose broken down  Leads into cellular respiration (aerobic/anaerobic) or fermentation Aerobic Anaerobic Fermentation Krebs cycle: high energy Part of Krebs cycle: low energy No Krebs Electron transport chain Electron Transport chain No ETC Final Acceptor: O2 Final acceptor: does not use O2 Various organic end products Inorganic product
  18. 18. Copyright © 2010 Pearson Education, Inc. Metabolic Diversity among Organisms  Photoautotrophs  Photoheterotrophs  Chemoautotrophs  Chemoheterotrophs  Autotrophs – fix carbon  Heterotrophs – cannot fix carbon  Chemotrophs – energy from oxidation  Phototrophs – energy from light
  19. 19. Copyright © 2010 Pearson Education, Inc. The Requirements for Growth: Physical  Physical requirements  Temperature  pH  Osmotic pressure
  20. 20. Copyright © 2010 Pearson Education, Inc. Physical Requirements  Temperature  Minimum growth temperature  Optimum growth temperature  Maximum growth temperature
  21. 21. Copyright © 2010 Pearson Education, Inc. Temperature  Three primary Groups 1.Psychrophiles – cold loving 2.Mesophiles – moderate 3.Thermophiles – heat loving
  22. 22. Copyright © 2010 Pearson Education, Inc. Figure 6.1 Typical Growth Rates and Temperature
  23. 23. Copyright © 2010 Pearson Education, Inc. Psychrotrophs  Grow between 0°C and 20–30°C  Cause food spoilage
  24. 24. Copyright © 2010 Pearson Education, Inc. Figure 6.2 Food Preservation Temperatures
  25. 25. Copyright © 2010 Pearson Education, Inc. pH  Most bacteria grow between pH 6.5 and 7.5  Molds and yeasts grow between pH 5 and 6  Acidophiles grow in acidic environments
  26. 26. Copyright © 2010 Pearson Education, Inc. Figure 6.5 Biofilms  Microbial communities  Form slime or hydrogels  Form on teeth, contact lenses and catheters
  27. 27. Copyright © 2010 Pearson Education, Inc. Applications of Microbiology, p. 57 Biofilms  Share nutrients  Sheltered from harmful factors  70% bacterial infections are from biofilms  100X more resistant to antibiotics than free swimming microbes
  28. 28. Copyright © 2010 Pearson Education, Inc. Agar  Complex polysaccharide  Used as solidifying agent for culture media in Petri plates, slants, and deeps  Generally not metabolized by microbes  Liquefies at 100°C  Solidifies at ~40°C
  29. 29. Copyright © 2010 Pearson Education, Inc. Culture Media  Chemically defined media: Exact chemical composition is known  Complex media: Extracts and digests of yeasts, meat, or plants  Nutrient broth  Nutrient agar
  30. 30. Copyright © 2010 Pearson Education, Inc.
  31. 31. Copyright © 2010 Pearson Education, Inc.
  32. 32. Copyright © 2010 Pearson Education, Inc. Anaerobic Culture Methods  Reducing media  Contain chemicals (thioglycolate or oxyrase) that combine O2  Heated to drive off O2  Used to grow anaerobes
  33. 33. Copyright © 2010 Pearson Education, Inc. Figure 6.7 An Anaerobic Chamber
  34. 34. Copyright © 2010 Pearson Education, Inc. Figure 6.10 Selective Media  Suppress unwanted microbes and encourage desired microbes
  35. 35. Copyright © 2010 Pearson Education, Inc. Figure 6.9 Differential Media  Make it easy to distinguish colonies of different microbes.
  36. 36. Copyright © 2010 Pearson Education, Inc. Figure 6.11 The Streak Plate Method
  37. 37. Copyright © 2010 Pearson Education, Inc. Preserving Bacterial Cultures  Deep-freezing: –50° to –95°C  Lyophilization (freeze-drying): Frozen (–54° to – 72°C) and dehydrated in a vacuum
  38. 38. Copyright © 2010 Pearson Education, Inc. Measuring Microbial Growth Direct Methods  Plate counts  Filtration  MPN  Direct microscopic count Indirect Methods  Turbidity  Metabolic activity  Dry weight
  39. 39. Copyright © 2010 Pearson Education, Inc.  Standard plate count  Viable count  Microscopic count  No incubation time  Growth phase gram + is suseptible to penic.  LOG phase

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