Amylase Test

What is Amylase Test?

  • Amylase (E.C is an exoenzyme that hydrolyses starch, a polysaccharide into maltose, a disaccharide and some monosaccharides such as glucose.
  • These diasaccharides and monosaccharides enter into cytoplasm of the bacterial cell through the semipermeable membrane and there are used by the endoenzymes.
  • Starch is a complex carbohydrate composed of two constituents-amylose, a straight chain polymer of 200-300 glucose units and amylopectin, a larger branched polymer with phosphate group. Both, amylose and amylopectin are made up of D-glucose units. In amylose the glucose units are linked by 1,4 a-glucosidic bonds. In amylopectin the glucose units are linked by both, 1,4 a- and 1,6 a-glucosidic bonds.
  • Amylase catalyses the hydrolysis of 1,4 a-glucosidic bonds of polysaccharides such as starch and glycogen. There are two types of amylases, namely, a -amylase (endoamylase) and B amylase.
  • The hydrolysis of starch by a-amylase occurs randomly releasing a large amount of oligosaccharides or dextrin. The dextrin is then hydrolyzed, yielding a large quantity of maltose and little glucose and maltotriose.
  • Amylase production is known in some bacteria while well known in fungi.
  • Amylases commercially produced from various aspergilli are used in the initial steps in several food fermentation processes to convert starch to fermentable sugars. They are also used to partially predigest foods for young children, to clarify fruit juices and in the manufacture of corn and chocolate syrups.

Principle of Amylase Test

The ability to degrade starch is used as criterion for the determination of amylase production y a microbe. In the laboratory it is tested by performing the starch test to determine the absence or presence of starch in the medium by using iodine solution as an indicator. Starch in the presence of iodine produces a dark blue coloration of the medium and a yellow zone around a colony in an otherwise blue medium indicates amylolytic activity.

Amylase catalyses the hydrolysis of 1,4 a-glucosidic bonds of polysaccharides such as starch and glycogen. There are two types of amylases, namely, a -amylase (endoamylase) and B amylase.

Why do I need an amylase test?

Starch is made up of amylase and amylopectin. In specific conditions like pancreatic disorders and diabetic conditions Amylase test is recommended to the patient for detection the ability of pancreas to degrade the starch and amylase to form simple sugars. Amylase test is recommended if following symptoms are occurred in the patient:

  • Pain in your upper abdomen (belly) that may spread to your back or get worse after eating
  • Loss of appetite
  • Nausea and vomiting
  • Fever
  • Fast heartbeat
  • Jaundice
  • Greasy, foul-smelling stool (poop)
  • Chronic pancreatitis
  • Pancreatic cancer
  • Eating disorders
  • Cystic fibrosis
  • Alcohol use disorder
  • Recovery from having gallstones removed after a gallbladder attack

Requirements of Amylase Test

  1. Sterile starch agar plate
  2. 1 gram of soluble starch is added in 100 ml of distilled water.
  3. The starch solution is heated till the solution becomes clear. Ingredients of nutrient broth are then added into this solution.
  4. The pH is adjusted after the medium has cooled to the ambient temperature.
  5. After adjusting the pH, agar (in appropriate concentrations) is added.
  6. The medium is autoclaved at 121°C for 15 minutes. After allowing the medium to cool to around 60°C, the medium is poured into sterile petri plates. The plates are allowed to solidify.
  7. The test culture suspension.


  1. The test culture suspension is to be spot inoculated in the center of the starch agar plate.
  2. The plate is incubated at 37°C for 24 hours.
  3. After incubation, Gram’s iodine solution is poured on the surface of the agar.
  4. Excess iodine solution is drained off.
  5. The clear zone of starch hydrolysis is detected.

Observation of Amylase Test

Result and Interpretations of Amylase Test