Urea Slant_生物行

Monday, November 24, 2003

Description
To determine the ability of an organism to split urea by the action of the enzyme urease forming two molecules of ammonia with resulting alkalinity.

Procedure
From one isolated colony, heavily inoculate the urea slant.

Incubate O2, 35C.

Read at 3 hours and again at 18-24 hours.

Interpretation

Positive: Intense pink-red colour.
Rapidly positive: 1 to 6 hours (Proteus spp.)
Delayed positive: > 18 hours

Negative: No colour change

Precautions

Urea test media rely on the demonstration of alkalinity, thus are not specific for urease. The utilization of peptones or other proteins may cause an increase in pH.

Quality Control

Controls should be set up weekly:

P. mirabilis (ATCC 12453): Positive - 4 hours
K. pneumoniae (ATCC 13883): Weak positive - 18 hours
E.coli (ATCC 25922): Negative

Recipes
Urea Slant
Bacteriology loop

Supplies

Tips

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Urea Slant