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36: Bile Esculin

  • Page ID
    3668
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    Learning Objectives

    • Identify the organism's ability to grow in high bile concentration and to use the sugar esculin

    BILE ESCULIN

    Bile esculin agar comes in a slant form. It is 2 tests in one---resistance to 40% bile AND the use of the sugar esculin. Bile is a very inhibitory chemical, particularly at that concentration. IF the bacterium grows, the next question is whether it uses the esculin.

    If your bacterium cannot grow in the presence of bile, the esculin reaction will have to be obtained a different way, using an esculin sugar disc

    MATERIALS NEEDED

    • 1 bile esculin slant per unknown

    THE PROCEDURE

    1. Using your unknown, streak the inoculum up the slant.
    2. Incubate the medium at 25º C or 37º C.

    INTERPRETATION

    1. Growth on the slant = resistance to 40% bile
    2. Use of esculin sugar = slant turns black coffee (over 1/2 of slant or entire agar) color

    QUESTIONS

    1. The presence of growth on bile esculin means __________.
    2. What is esculin?

    Contributors and Attributions


    36: Bile Esculin is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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