Hydrolysis Tests Slides

Some bacteria produce enzymes that

can digest extracellular materials

These materials are usually common barriers to other cells, such as

Casein, Gelatin, Starch, Lipids

When these enzymes break down these macromolecules, they produce

water

we can determine whether a microorganism produces these enzymes by whether or not they are able to

liquify media solidified using these macromolecules

Starch Hydrolysis Test: step 1

Culture sample on a starch-agar plate with your microorganism

Starch Hydrolysis Test: step 2

Incubate overnight at 37° C

Starch Hydrolysis Test: step 3

Flood plate with Gram’s iodine for 30 seconds. Pour off excess

Starch Hydrolysis Test: step 4

Examine cultures. Cultures which can digest starch will appear clear around the streak. This is because iodine dyes starch.

What dyes starch

Iodine

Gelatin Hydrolysis Test: step 1

Make a stab culture in nutrient gelatin tube

Gelatin Hydrolysis Test: step 2

Incubate overnight at 37° C

Gelatin Hydrolysis Test: step 3

Examine cultures. Cultures which can digest gelatin will have liquified the media

What is this

Starch Hydrolysis Test Result

What is this

Gelatin Hydrolysis Test Result