| Technique | CATALASE ,(/,)/,( |
| Principle | Most aerobes produce the enzyme catalase which splits hydrogen peroxide to give water and oxygen. |
| Cautions | As the hydrogen peroxide will kill
the colonies you may wish to pick individual colonies and
make a suspension on a microscope slide w ith a drop of
water and then add the hydrogen peroxide. The 3% hydrogen peroxide must be fresh and is usually stored in the refrigerator, but it should be allowed to warm up before doing the test. Colonies from blood agar must be picked with care as the erythrocytes in blood agar also contain catalase. |
| Method | To perform the test a few drops of
hydrogen peroxide are poured onto colonies on a T soy
plate or slant that has been incuba ted for 24-48 hours The test may be performed with a 24-48 broth culture for microaerophiles or with thioglycollate medium for anaerobes. |
| Results | Vigourous bubbling, caused by the generation of oxygen indicated the presence of catalase. |
| Positive control | Bacillus and Staphylococus |
| Negative control | Streptococcus faecalis Any of the Streptococci will work but this species is less difficult to maintain |
| Reagents | |
| Reference |