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  Section: Microbiology Methods » Diagnostic Microbiology In Action
 
 
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The Activity of Catalase

 
     
 
Content
Diagnostic Microbiology In Action
  Principles of Diagnostic Microbiology
    Primary Media for Isolation of Microorganisms
    Some Metabolic Activities of Bacteria
      Simple Carbohydrate Fermentations
      Starch Hydrolysis
      Production of Indole and Hydrogen Sulfide, and Motility
    Activities of Bacterial Enzymes
      The Activity of Urease
      The Activity of Catalase
      The Activity of Gelatinase
      The Activity of Deoxyribonuclease (Dnase)
      The Activity of a Deaminase
    Principles of Antigen Detection and Nucleic Acid Assays for Detection Identification of Microorganisms
      Antigen Detection Assays
      Enzyme Immunoassay (Eia)
      Nucleic Acid Detection Assays

Many bacteria produce the enzyme catalase, which breaks down hydrogen peroxide, liberating oxygen. The simple test for catalase can be very useful in distinguishing between organism groups. The hydrogen peroxide can be added directly to a slant culture or to bacteria smeared on a clean glass slide. The test should not be performed with organisms growing on a bloodcontaining medium because catalase is found in red blood cells.

Purpose To observe bacterial catalase activity
Materials 3% hydrogen peroxide
Capillary pipettes
Pipette bulb or other aspiration device
Nutrient agar slant cultures of Staphylococcus epidermidis and Enterococcus faecalis
Clean glass slides
China-marking pencil or marking pen


Procedures
  1. Divide a clean glass slide into two sections with your marking pen or pencil.
  2. With a sterilized and cooled inoculating loop, pick up a small amount of the Staphylococcus culture from the nutrient agar slant. Smear the culture directly onto the left-hand side of the slide. The smear should be about the size of a pea.
  3. Sterilize the loop again and smear a small amount of the Enterococcus culture on the right-hand side of the slide.
  4. With the capillary pipette, place one drop of hydrogen peroxide over each smear. Be careful not to run the drops together.
    Observe the fluid over the smears for the appearance of gas bubbles (see fig. 18.1). Record the results in the chart. Discard the slide in a jar of disinfectant.
  5. Hold the slant culture of the Staphylococcus in an inclined position and pipette 5 to 10 drops of hydrogen peroxide onto the surface with the bacterial growth. Observe closely for the appearance of gas bubbles.
  6. Repeat the procedure with the Enterococcus culture. Note whether oxygen is liberated and bubbling occurs.
 
Slide catalase test. Staphylococcus epidermidis on the left produces a strong positive catalase reaction. Enterococcus faecalis on the right (cloudy area in drop of hydrogen peroxide) is negative in the catalase test.
Figure 18.1 Slide catalase test. Staphylococcus epidermidis on the left produces a strong positive catalase reaction. Enterococcus faecalis on the right (cloudy area in drop of hydrogen peroxide) is negative in the catalase test.


Results
Record your observations and conclusions in this chart.


 
     
 
 
     




     
 
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