What is this medium used for? Bacteria are identified based largely on what organic compounds they can break down. The range of compounds used depends on the collection of enzymes a species of bacteria can make. Urea is a compound that some bacteria can use because of an enzyme called urease that breaks down this compound. Christiansen’s urea broth is thus used to determine whether the microbe can use the compound urea for carbon and energy.
How is urease production determined? If urea can be used, the microbe will accumulate alkaline/basic byproducts. In a positive test, the pH indicator in the medium changes color from its normal red to magenta (hot pink), indicating alkaline/basic products.
What is the content of this medium? The medium is a nutrient broth to which 2.0% urea is added. The pH indicator is phenol red, which is red at neutral pH but turns yellow at pH <6.8. It also changes to magenta or hot pink at pH >8.4.
How is the test performed? For information on how to determine the ability of a microbe to use urea, refer to the urease (Christiansen's) test.