Urease Test
The purpose of this test is to determine whether an organism can split urea into ammonia and carbon dioxide by the action of the enzyme urease. Christensen's urea medium without agar is used. The production of ammonia leads to alkalinity in the medium and will cause the medium to turn red (the indicator used is phenol red). 1. Uninoculated medium. 2. Positive reaction: Proteus. 3. Negative reaction: Salmonella. The medium is more yellow than the uninoculated medium due to acid produced during fermentation of glucose.
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