Lecture 12: Microbial Growth Cont. (Quiz 6)

  1. Barophiles
    • This is a physical influence on the pattern of growth
    • Part of Hydrostatic Pressure
    • Describes high or low pressures of growth
  2. Halophiles
    • This is a physical influence on growth
    • These are organisms that love salt
  3. Nutritional Factors Affecting Bacterial Growth?
    • Essential for all Life: Carbon, Sulfur Nitrogen, Phosphorus
    • Trace Elements: Metals (enzyme donor/accepter)
    • Vitamins: Co-enzymes
    • Chemically Defined: Knowing exactly what is in a medium
    • Complex: Different amount of things used that aren't defined
  4. Aerobes
    • Use O2 in their metabolic pathways
    • During the electron transport chain
  5. Anaerobes
    Do not use O2 in their metabolic pathways
  6. Obligate Aerobes
    • Only Oxygen
    • In tube: Sediment at the top, growth occurs where high concentrations of oxygen have diffused into the medium
  7. Microaerophiles
    • Aerobes
    • Prefer a small amount of oxygen
    • In tube: Sediment towards the center of the tube, growth occurs where a small level of oxygen has diffused
  8. Obligate Anaerobes
    • Killed by oxygen
    • Magnetesomes
    • In tube: Sediment is at the bottom, growth occurs where there is no oxygen
  9. Facultative Anaerobes
    • Prefer oxygen, but can live without it (with or without)
    • In tube: Sediment more on top but also spread throughout, growth occurs where there is oxygen but it everywhere
  10. Aerotolerant Anaerobes
    • Survive in oxygen but don't use it (doesn't make a difference)
    • In tube: Sediment spread out evenly, growth occurs throughout (there isn't more in one single place)
  11. Controlling Oxygen
    • Candle Jar: Plug the cultures and agar media, out in a sealed jar to suck out all of the air. Gave it an anaerobic environment. However, sometimes things wouldn't be sealed correctly.
    • Anaerobic Jars: Sealed jars with gaskets so no air would get in, envelopes were put in to create the correct environment, then there was an indiciator.
    • Anaerobic Hoods: Completely no oxygen and sealed off so everything could be done in the correct environment for the specific bacteria. Double chamber.
    • Aeration: Shake the particular jar/incubation to create oxygen.
  12. Quorum Sensing
    • Intra (only you) and Inter (all bacteria) signalling
    • Every bacterial disease caused through this
    • Cells settle on a surface, synthesize sticky substrate that holds them to substrate, few cells have a low indicator level, after biofilm grows to certain molecules cause expression of specific genes, secrete enzymes in unison to get food, signaling molecules induce expression of protein product
  13. Selective Media
    • Encourages come media and suppresses others
    • Only one
  14. Differential Media
    • Growth causes an observable change
    • Color, growth, etc.
  15. Enrichment Media
    • Aims to grow one particular organism that usually is to low to detect
    • Grows everything
    • Has specific nutrient that helps one grow faster than the other
  16. Triple Sugar Agar (TSI Agar)
    • 3 Different sugars
    • Glucose (0.1%)
    • Lactose (1%)
    • Sucrose (1%)
    • Iron Salt (Black, H2S, Sulfur)
    • Phenol Red (pH Indicator, acidic=yellow)
    • You inoculate it twice (poke it and smear it)
    • Slant: Can either be NR (neutral reaction=still red) or A (acidic=yellow)
    • Butt: NR, A (yellow or black), @ (yellow or black with gas), + (black), - (not black)
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  17. Preserving Cultures
    • 80 Freezer: Celsius, quick and works well, problem is the power goes out.
    • Lyophilization: Freeze-drying, turns it into sort of a beef jerky (dehydrates), very expensive
    • ATCC (American Type Culture Collection): Collection of all bacterial strains
  18. Serial Dilutions
    • Diluting a large population of bacteria in a series until you have only a few colonies that are countable. 
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  19. Direct Counting
    • Counting individual colonies (Colony Forming Units) on a plate, remember each colony was only one microbe at one time.
    • Machine Count: Never works, usually have a clicker in one hand
    • Hemocytometer: Slide with shallow walls, like a grid. Bacterial cells in square grid are counted. Won't know if it's living or dead.
    • Most Probable Number: Helps narrow down a specific number very quickly for specific populations.
Card Set
Lecture 12: Microbial Growth Cont. (Quiz 6)
Cont. of bacterial growth