3.6.1: Urease Test

OER - BIOL 2420 Laboratory Manual · LibreTexts

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    The urease test is performed to determine if a bacterium can produce urease. Urea is a metabolic waste product produced as a result of protein catabolism. Some bacteria can hydrolyze urea releasing ammonia and carbon dioxide. These bacteria use the enzyme urease to accomplish this hydrolysis, freeing ammonia to be used as a nitrogen source in the bacterium’s metabolism.

    The test is performed using urea broth, which contains urea, growth factors, and the pH indicator phenol red. Phenol red is pink (fuchsia) above pH 8.2 and yellow at pH 6.8. The media has a pH of 6.8 and therefore begins as a yellow color. The medium is inoculated, incubated, and then observed. If the bacterium has urease the production of ammonia will cause the media to become more alkaline therefore causing the media to change to a pink (fuchsia) color.

    Urease Test Results
    Positive for Production of Urease Negative for Production of Urease
    Examples:

    Proteus vulgaris

    Klebsiella pneumoniae

    Staphylococcus aureus

    Staphylococcus epidermidis    		 Examples:

    Escherichia coli

    Enterobacter aerogenes

    Enterococcus faecalis

    Alcaligenes faecalis
    Urease Test - (A) Urease positive (left); (B) Urease negative (right)
    Urease Test - (A) Urease positive; (B) Urease negative. Credit: Sherry Smith

    This page titled 3.6.1: Urease Test was last modified on Sat, 25 Jul 2026 03:43:07 GMT and is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Sherry Smith.