Ch' 7: Whats your favorite environment

1
Ch. 7 Whats your favorite environment?

• Whats your favorite
• pH
• temperature
• source of nutrients
• solute concentration
• energy source

2
In order to speak the language, you need to know
the words...

• Define the following terms
• 1. Macromolecule
• 2. Micronutrient
• 3. Heterotroph
• 4. Autotroph
• 5. Fastidious
• 6. Photoautotroph
• 7. Chemoautotroph
• 8. Chemoheterotroph
• 9. Optimum growth temperature
• 10. Psychrophile
• 11. Mesophile

3
In order to speak the language, you need to know
the words...

• 12. Thermophile
• 13. Aerobe
• 14. Facultative anaerobe
• 15. Microaerophilic
• 16. Anaerobe
• 17. Aerotolerant anaerobe
• 18. Halophile (osmophile)
• 19. Binary fission
• 20. Generation time
• 21. Exponential growth
• 22. Selective media
• 23. Differential media

4
?? Who am I ??

• I love the cold winter days!
• (Proteus, Pseudomonas)

5
?? Who am I ??

• I like it not tooooo cold and not tooooo hot
  !!!!!!!
• (E. coli)

6
?? Who am I ??

• I like it hot!!!!
• (Bacillus stearothermophilus)

7
pH

• Optimal pH range

Opt. pH range for most bacteria
Opt. pH range for molds, yeasts, Lactobacillus
Vibrio cholera
7.0
6.5
7.5
9.0
8
pH tolerance by certain bacteria

• pH range and optimum

9
?? Who am I ??

• I have to have oxygen !
• (My. Tuberculosis, Pseudomonas)

10
?? Who am I ??

• I need oxygen, but not soooo much!
• A little more carbon dioxide would be good too!
• (Lactobacillus)

11
?? Who am I ??

• I hate oxygen, in fact Ill die if exposed to it
  !!
• O2 2H H2O2
• (Clostridium, Bacteroides)

12
?? Who am I ??

• Do you let others cook for you, or do you make
  your own?
• SPONCH
• I let others cook for me
• I make all my own food
• nutrient cycling
• micronutrients

13
Where do you get all that ENERGY from???

• From the sun
• eg.
• From inorganic molecules
• eg.
• From organic molecules
• eg.

14
?? Who am I ??

• I love lots of salt ! (15-30 NaCl)
• I can survive in a wide range of salt concs, but
  prefer 3 NaCl
• I dont like a lot of salt, I have a very narrow
  osmotic range (0.85 NaCl)

15
Why does salt concentration matter?

• Hypotonic
• Hypertonic
• Isotonic

16
My, how youve grown!

• Exponential growth - class activity
• be able to explain activity, and apply concept
  and terminology

17
Bacterial Growth Curve

• Phases of growth
• Lag phase
• Log phase
• Stationary phase
• Death phase
• Survival phase

time
18
Techniques for measuring bacterial growth

• Plate count
• direct, dilutions, filtration
• MPN
• Direct microscopic count
• Indirect methods
• turbidity, metabolic activity, dry wt.