Wednesday, June 24, 2009

Catalase Test

What is catalase test?
Catalase is an enzyme that decomposes hydrogen peroxide into oxygen and water.This test is used to distinguish Gram-positive cocci,to differentiate between streptococci for staphylococci. To run this test we will need well isolated colonies of an 18-24 hours cultures, 3%hydrogen peroxide solution, clean glass slide, enoculating loop and a dropper.

How would we go about running this test?
1.transfer cells from centre of the isolated colonies onto the clean glass slide
2.add 2 drops of 3% hydrogen peroxide directly onto the smear
3.record the observation

What are the observations?
*Catalase-Positive will form gas bubbles rapidly
*Catalase-Negative will have no production of gas bubbles

Member of the Staphylococcus are catalase-positive.
Members of the Streptococcus are catalase-negative.