Different Media Types - Midterm 1 Flashcards
How to determine if a microbe is present?
- Grow it in broth
- Grow in a plate
- see if theres any physiology (change in pH)
Whats in a medium?
- Protein (peptones)
- Sugar
- Salts
- water
- micronutrients
What is a peptone?
Digested amino acids
What is a General all purpose media?
- Very rich in nutrients
- Not exactly weighed out in the contents
- Undefined
What is a well defined medium?
- you know exactly whats in tehre
- Theres minimal media
- Used to test the survivability for the organism you have
What is Selective medium
- Inhibits growth
2. It inhibits NON TARGET organisms
What is differential medium?
- Ingredients that will differentiate among organisms
2. The basis for this is physiological effects
What is enriched medium?
something that has been added to an organism with specific needs to encourage its growth
What is TSA and which medium does it belong to?
belongs to general all purpose medium
Tryptocase soy augur.
What is NA and which medium does it belong to?
Nutrient agar
2. it belongs to general all purpose medium
What is MacConkey and which medium does it belong to?
MacConkey is selective and differential
Selective: The crystal violet, Bile salts, and it selects against gram +
Differential: contains lactose and neutral red (pH indicator)
In detail, explain how lactose fermentation leads to change in color of medium
Lactose fermentation releases amine in amino acids and this causes the pH to go up making the medium yellowish Brown.
Why is there an opaque pink color when e.coli is present in MacConkey?
Acid is produced in high amounts and the medium turns opaque because the bile salts get ppt out.
Levine EMB
is a selective and differential
What is fastidious organism?
those who have complicated nutritional reqs. and need special media to permit growth.
What is blood augur?
Differential medium that is not selective.
its considered to be an enriched medium because it allows for the growth of fastidious organisms too
What are coliforms
anaerobic gram negative bacteria capable of fermenting lactose in the presence of bile to produce acid and gas
Alpha hemolytic?
partial hemolysis resulting in green/greenish brown halo around colony
Beta hemolytic?
complete lysis of red blood cells; looks like complete clearing of the colony
Gamma hemolytic?
no hemolysis, no change in the medium
