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. Lipids are organic compounds that some bacteria can use for carbon and energy. The enzyme capable of breaking down lipids is called lipase. Spirit blue agar is a medium that contains a supply of lipids, and thus it allows us to determine the presence of lipase.
How is lipase activity determined? If lipase is made by the bacterium, the lipids in Spirit blue agar will be digested. The medium, which is normally opaque and light blue in color, will have halos around colonies of bacteria that make lipase.
What is the content of this medium? Spirit blue agar is a nutrient medium with the dye spirit blue present. It also contains an emulsified lipid to serve as the target for the enzyme. For the test in this program, that emulsified lipid is assumed to be corn oil.
How is the test performed? For information on how to determine the ability of a microbe to use lipids, refer to the Lipase (corn oil) test.