You place an inoculum of your bacterium on a glass slide and add a drop of hydrogen peroxide reagent. Promptly you see bubbles appear, indicating the presence of a particular enzyme that the bacterium produces. What type of identification test does this exemplify?
A) Biochemical test
B) Immunochromatography
C) Microarray
D) Precipitation test

In microbiology biochemical test is used to examine the metabolic activities performed by bacteria to identify that microorganism. So in biochemical test enzymatic reaction of cell is usually investigated because there is difference in enzymatic activity of different species of bacteria.

For example, catalase test that is used to differentiate between catalase-positive and catalase-negative bacteria is an example of biochemical test. Catalase-positive bacteria have the catalase enzyme that breaks hydrogen peroxide into water and oxygen which is confirmed by bubbles that appear on glass slide.

Catalase negative bacteria do not form bubbles when they are put in hydrogen peroxide which shows that they lack catalase enzyme. So the right answer is A.