Question

Exercise 40: I A B B 1. What is the name of this test? 2. Which test is positive? 3. Which test is negative? 4. What enzymes are being tested for with this test? 5. What is the function of the enzymes being tested for?

Answer 1

1. name of the test: Starch Hydrolysis Test

     Bacteria consuming starch as an energy source. But starch molecules cannot pass through the bacterial cell wall due to the larger size of its components amylose and amylopectin. Bacterias can use starch only after breaking it into smaller subunits such as maltose and glucose etc. The starch hydrolysis test used to identify the starch hydrolyzing ability of bacteria such as Clostridium and Bacillus. The result of the test can be interpreted only if we added iodin into the media. Iodin along with starch will provide a dark blue color for the media. So the bacteria will create a clear zone around the plate when it consumes the starch from the plate by breaking it with $\alpha$ - amylase secretion.

2. Positive test: B

        Created a clear zone in the media. Indicating the amylase secretion ability of bacteria to hydrolyze starch

3. Negative test: A

      No clear zone. No starch is consumed. Blue color indicating that both starch and iodine remaining in the media.

4. Enzyme being tested: $\alpha$ - amylase

5. The function of the enzyme being tested: Hydrolysation of starch by cleaving the glycosidic linkage between sugar subunits amylase and amylopectin.