Used to determine if bacteria produce extracellular enzymes to catalyze the hydrolysis of starch. Organisms that produce a starch hydrolyzing enzyme will display a clear zone around the area of growth while other areas of the agar containing starch will turn blue-black.

• Starch agar is inoculated and incubated at 37 °C
• After 48 hours the surface of the agar is flooded with potassium/potassium iodide solution

To prepare media, add 25 g of starch agar to a liter of distilled or de-ionized water. Follow instructions. The media will not be sterile until autoclaved prior to use.