Quiz 3 Flashcards
Which dilution plate should be recorded
you should use (69 if it’s (10^-70 ) because it is between 30-300 colonies
Calculate the CFU for 69
6.9 x 10^8
How is sulfide production tested
black precipitate
What is motility and what is a positive result?
- motility is the movement of bacteria
- positive result is growth outside the line of inoculation
E. coli tube dilution question:
10^-3, 10^-4, 10^-5, 10^-6
Final dilution factor
10^3, 10^4, 10^5, 10^6
What is tryptophatanase? What is it important for?
an enzyme that breaks down tryptophan important for the SIM test
What is the purpose of nitrate? What reagents are added to test for it?
Nitrate: final electron acceptor
-zinc and sulfanic acid are added
The presence of what is detected in the protein hydrolysis test? What does a positive test look like?
- caesin is detected
- a clear zone
What is catalase and what reaction does it facilitate?
-catalase is the enzyme that catalyzes the reaction:
H2O2 -> H2O + O2 (bubbles)
What does a positive catalase test produce and why does this happen?
- positive test: produces bubbles
- the bubbles are a result of the water and O2 formation
What makes an oxidase test positive? What is the color change?
- positive test is when it is converted being converted to H2o
- color change: blue
List 3 approaches for enumerating viable bacteria
- cell turbidity
- viable cell count
- direct microscopic count
