Quiz 5 Micro

Question 1

Starch Hydrolysis

Answer 1

Purpose: Detect the production of amylase enzyme, it will break down starch and clear a zone around the organism
Medium: Starch Agar Plate
Results:
Significant Ingredients: Starch 1%
Reagents: Gram’s Iodine. When it comes into contact with starch it turns blue-black.
Specific directions: Do not flood plate with iodine
(+) if there is a clear zone around the organism the color of the iodine.
(-) No zone around the organism, the medium is blue-black
Significant results: Only 2 positives. B. cerus and subtilis
SIgnificant information: Useful for Gram + Cocci/Rods

Question 2

Casein Hydrolysis

Answer 2

Purpose: Test for casease enzyme
Medium: Skim milk agar
Results: Positive result is a halo around organism indicating casein hydrolysis via casease
Significant Ingredients:
Reagents:
Specific directions:
Significant results:  B. cerus and subtilis both had a large halo around growth. Sarcina aurantica was positive with a skinny halo.
SIgnificant information:

Question 3

Urea hydrolysis

Answer 3

Purpose: Detect urease enzyme
Medium: Urea broth
Results: 
(+) Red/Pink Ph above 8.4
(-) Yellow pH below 6
Significant Ingredients: Urea and phenol red. if the enzyme urease was produced it will hydrolyze the urea in the broth to ammonia and CO2. The ammonia will increase the pH. The phenol red will physically show this change.
Reagents: Phenol red
Specific directions:
Significant results:
SIgnificant information:

Question 4

Gelatinase Production

Answer 4

Purpose: determine the production of gelatinase
Medium: 12-15% gelatin
Results: Gelatinase causes the breakdown and liquefaction of gelatin. If the organisms produce gelatinase then the medium will turn liquid.
(+) liquefaction aster refrigeration
(-) Gels when refrigerated
Significant Ingredients:
Reagents:
Specific directions: Deep stab inoculation
Significant results:
C. freundii and S. epidermis: A lot of liquid
Serratia marcescens: all liquid and pink top
B cerus: all liquid and white chunks
B. subtilis liquid, red slimy clot
SIgnificant information: Test does not detect weak positives and concentration of gelatin can inhibit grown of some organism

Question 5

Indole test

Answer 5

Purpose: Indole. Test for enzyme tryptophanase
Medium: TA plate
Results:
Significant Ingredients:
Reagents: Indole dry slides used with growth from TA plate
Specific directions:
(+) color change within 30 sec
(-) no color change
Significant results:
Gram - rods
E. coli and S. marcescens (growth is already pink)
SIgnificant information:

Question 6

Kligler’s Iron Agar

Answer 6

Purpose: differentiate between Enterobacteriaceae by fermentation of dextrose, lactose, and production of H2S
Medium: KIA sulfate, phenol red, dextrose, lactose
Results:
Significant Ingredients:
Reagents: phenol red
Dextrose: but turns yellow
Lactose: Butt and salt both are yellow
Gas: Breaks in medium
H2S: Butt black
Specific directions: Gram - rods
Significant results:
SIgnificant information: Citrobacter freundii is supposed to be a pos for H2S

Question 7

IMViC tests

Answer 7

Purpose: Identify gram - rods
Medium:
Results:
Significant Ingredients:
Reagents:
Specific directions:
Significant results:
SIgnificant information: