Lecture 12: Microbial Growth Cont. (Quiz 6)
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- This is a physical influence on the pattern of growth
- Part of Hydrostatic Pressure
- Describes high or low pressures of growth
- This is a physical influence on growth
- These are organisms that love salt
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
- Use O2 in their metabolic pathways
- During the electron transport chain
Do not use O2 in their metabolic pathways
- Only Oxygen
- In tube: Sediment at the top, growth occurs where high concentrations of oxygen have diffused into the medium
- 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
- Killed by oxygen
- In tube: Sediment is at the bottom, growth occurs where there is no oxygen
- 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
- 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)
- 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.
- 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
- Encourages come media and suppresses others
- Only one
- Growth causes an observable change
- Color, growth, etc.
- 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
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)
- 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
- Diluting a large population of bacteria in a series until you have only a few colonies that are countable.
- 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.
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