CMMB 343 lab final exam questions and answers 2024-2025 with complete solution
How to do .....
BHI stant
How to interpret results? - Slanted BHI agar in a test tube
Inoculate with the sample
Will see growth on surface of agar if aerobic microbe.
Fissures and cracks below surface if able to ferment.
Deep shake culture - Innoculate a loop of sample in molten agar and rotate in hands to
mix.
If fissures below the surface, can ferment.
If no fissures, cannot ferment.
Thioglycollate Medium - Pipette some liquid culture to the bottom of the tube BELOW the pink layer. Turbidity will show where the microbes are able to survive. This is based on the oxygen gradient within the tube.
A facultative aerobe will show what results in a thioglycollate tube? - Turbidity all throughout the tube, but a bit more turbid in the top segment.
What is the upper pink layer of a thioglycollate tube? - oxygenated layer
When they say "oxygen is a nutrient" what is meant? - It is needed as the final e- acceptor in the ETC to generate ATP.
Name 2 enzymes that are part of respiration. What 2 tests can be used to detect them? - cytochrome c oxidase
Oxidase test
catalase Catalase test
How to do and interpret....
oxidase test - -hold the RED end of oxidase stick
-put BROWN end into cells
Negative result: colourless
Positive result: blue
How to do and interpret....
catalase test - Add 2 drops of hydrogen peroxide to a colony on an agar plate
if bubbling, catalase is present
What are the gas bubbles you see in a positive catalase test? - O2
The enzyme catalase converts the added Hydrogen Peroxide to ___________ and ___________. - water and oxygen gas
How to do and interpret....
H&L glucose test - use 2 H&L glucose test tubes. These have glucose as a carbon source in the medium.
Shows if and where the species can use glucose as a carbon source.
Inoculate both and add a layer of mineral oil to the top of one of them. POSITIVE = turns yellow
NEGATIVE = stays green
What does it mean if the top layer turns blue in an H&L glucose test? - Negative result
Colour change occurred due to the organisms using peptones in the medium and excreting alkaline end products. NOT carbohydrate utilization.
How to do and interpret...
H&L lactose test - use 2 H&L lactose test tubes.
These have lactose as a carbon source in the medium.
Shows if the species can ferment lactose.
Inoculate both and add a layer of mineral oil to the top of one tube.
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Wiseman. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $13.99. You're not tied to anything after your purchase.