Final answer:
Starch agar is used in the Starch Hydrolysis Test to detect the hydrolysis of starch by microorganisms, which is revealed by adding iodine to the medium after incubation.
Step-by-step explanation:
Starch Hydrolysis Test Agar
The type of agar used in the Starch Hydrolysis Test is known simply as starch agar. Starch agar is a specialized medium that is used to detect the production of extracellular amylases by microorganisms which can hydrolyze starch. This is observed by adding iodine to the agar. In the presence of intact starch, a blue-violet color will appear due to the amylose-iodine complex. However, if an organism can hydrolyze starch, a clear halo around the bacterial growth will be observed indicating starch degradation.
Starch is critical for this test as it is composed of amylose and amylopectin, which are glucose polymers. Amylose forms a helical structure that traps iodine, thus giving a characteristic color, which serves as the indicator in this test. Agar a sulphated galactose, forms a gel upon cooling, providing a stable platform for the starch and the bacteria to interact.