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Microbiology Lab Final

Terms in this set (57)

What is the media for the lipid hydrolysis?
Spirit blue agar
What does the lipid hydrolysis test for?
the break down of lipids; or lipase enzyme
What does a positive lipid hydrolysis result look like?
clearing in agar around growth
What is the media of the starch hydrolysis?
starch agar
What does the starch hydrolysis test for?
the breakdown of starch; or amylase enzyme
What is the reagent in starch hydrolysis?
iodine
What does a positive starch hydrolysis test look like?
clearing in agar around growth after applying reagent
What media is used in the casein hydrolysis?
skim milk agar
What does casein hydrolysis test for?
the breakdown of protein casein; or casease enzyme
What does a positive casein hydrolysis test look like?
clearing in agar around growth
What media is used in the urea hydrolysis?
urea broth
What does urea hydrolysis test for?
the breakdown of urea; or the enzyme urease
What is the reagent or pH indicator of urea hydrolysis test?
phenol red
What does a positive urea hydrolysis test look like?
the broth will turn a rose or pink color
What media is used in the carbohydrate fermentation?
carbohydrate (sugar) tubes with phenol red and a durham tube
What do the sugar tubes test for?
carbohydrate fermentation
-acid/gas
What is the reagent or pH indicator of the carbohydrate fermentation test?
phenol red
What does a positive carbohydrate fermentation test look like?
If acid is positive, then the red broth will turn yellow.

If CO2 (gas) is positive, then the durham tube will have a bubble gap at the top.
What media is used in the Indole test?
SIM tube with solid media
What does Indole test for?
the breakdown (hydrolysis) of tryptophan; or the enzyme trytophanase
What reagent is used in the Indole test?
Kovac's reagent
What does a positive Indole test look like?
the reagent will turn bright red on top of the SIM media
What media is used for the MR test?
MR-VP broth (straw colored)
What does MR test for?
mixed acid fermentation
What is the reagent or pH indicator in the MR test?
methyl red
What does a positive MR test look like?
the broth will turn red after the reagent
What media is used for the VP test?
MR-VP broth (straw colored)
What does VP test for?
detects acetoin, a non-acid byproduct
What is the reagent or pH indicator in the VP test?
VP A&B
What does a positive VP test look like?
the broth will turn red after the reagent
What media is used in the citrate test?
green simmons citrate
What does citrate test for?
it determines if the organism can us citrate
What is the reagent or pH indicator of the citrate test?
bromothymol blue
What does a positive citrate test look like?
the media will turn a royal/prussian blue
What media is used in the H2S (sulfide) test?
SIM tube, solid media
What does the H2S test for?
the production of hydrogen sulfide
What is the reagent or indicator of the H2S test?
iron
What does a positive H2S test look like?
there will be black growth or precipitate in the SIM tube media
What media is used in the lysine decarboxylase test?
LD+ and LD- broth (purple)
What does the lysine decarboxylase test for?
lysine hydrolysis; or the enzyme lysine decarboxylase
What is the reagent or pH indicator of the lysine decarboxylase test?
bromcresol purple
What does a positive lysine decarboxylase test look like?
LD- is a control so no matter what should present as yellow.

The LD+ should present purple if it contains lysine (yellow if it does not)
What media is used in the oxidase test?
bacteria is collected from a TSA slant
What does the oxidase test for?
the cytochrome oxidase enzyme and electron transport
What is the reagent in the oxidase test?
the reagent is the oxidase disc
What does a positive oxidase test look like?
the disc will quickly turn maroon/black/purple once bacteria is applied
What media is used in the nitrate test?
nitrate broth
What does the nitrate test for?
nitrate reduction
What is the reagent or pH indicator in the nitrate test?
A&B reagents and sometimes C(zinc)
What does a positive nitrate test look like?
*If A&B are added and the nitrate turn red, then it is positive.

*If A&B are added and the nitrate has no change, then add C (zinc)
-If there is no change, then it is positive.
-If the broth then turns red, then it is negative.
What media is used in the catalase test?
TSA slant
What does catalase test for?
the breakdown of hydrogen peroxide; or the enzyme catalase
What is the reagent or indicator in the catalase test?
H2O2; hydrogen peroxide
What does a positive catalase test look like?
The solution will bubble in the presence of H2O2.
What do the hydrolysis, indole, nitrate, oxidase, and catalase tests look for?
They are testing for the presence or activity of a specific enzyme.
What does a (+/+) result mean in a carbohydrate fermentation test?
That means the fermentation of the sugar occurred causing the pH to drop resulting in yellow color.

This fermentation produced CO2 which lead to a bubble in the durham tube.
Why can't the carbohydrate fermentation tests result in a (-/+)
That would mean the solution was negative for acid but positive for a gas.

The gas can not be produced unless the sugar was fermented into a gas.
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