To study the organisms that are capable of producing the enzyme catalase.
Most aerobic and facultative bacteria utilize oxygen to produce hydrogen
peroxide. This hydrogen peroxide that they produce is toxic to their own
enzymatic systems. Thus, hydrogen peroxide acts as an antimetabolite.
Their survival in the presence of toxic antimetabolite is possible because
these organisms produce an enzyme called catalase. This enzyme converts
peroxides into water and oxygen.
The enzyme catalase, which is present in most microorganisms, is responsible
for the breakdown of toxic hydrogen peroxide that could accumulate in the cell
as a result of various metabolic activities into the nontoxic substances, water
The hydrogen peroxide formed by certain bacteria is converted to water and
oxygen by the enzyme reaction. This best demonstrates whether that organism
produces catalase or not. To do this test all that is necessary is to place a few
drop of 3% hydrogen peroxide on the organism as a slant culture. If the
hydrogen peroxide effervescence is present, the organism is catalase-positive.
Alternatively, a small amount of culture to be tested is placed on top of the
hydrogen peroxide. The production of gas bubbles indicates a positive reaction.
- Glass wares
- Test tubes with slant bacterial culture
- 3% hydrogen peroxide.
- Direct tube test: The tube is held at an angle and a few drops of 3%
hydrogen peroxide are allowed to flow slowly over the culture. The
emergence of bubbles from the organism is noted. The presence of bubble
displays a positive, indicating the presence of enzyme catalase. If no gas
is produced, this is a negative reaction.
- Slide technique: With the help of a sterile platinum loop, transfer a small
amount of culture onto a clean slide. About 0.5 mL of 3% hydrogen
peroxide is added to the culture.
If bubbles are formed, it indicates a positive reaction, i.e., the presence of the
Observe your experimental result.