Make your own free website on Tripod.com

Biochemical Test

Oxidase Test

Home
Biochemical Test
Agar Plates
Coagulase Test
The Catalase Test
Indole Test
Oxidase Test
Citrate Test
Optichin Test
Urease test
References

Oxidase Test

Cytochrome oxidase is an enzyme found in some bacteria that transfers electrons to oxygen. Thus, the enzyme oxidizes reduced cytochrome c to make this transfer of energy. Presence of cytochrome oxidase can be detected through the use of an Oxidase Disk which acts as an electron donator to cytochrome oxidase. If the bacteria oxidize the disk, the disk will turn purple, indicating a positive test. No color change indicates a negative test.

oxidasetest.jpg
http://medic.med.uth.tmc.edu/path/oxidase.htm

Procedures to carry out Oxidase test

 

  • Filter Paper Method

o    Soak a piece of filter paper in the reagent solution.

o    Scrape some fresh growth from the plate with a disposable loop or stick and rub onto the filter paper or touch a colony with edge of paper.

o    Examine for blue colour within 10 seconds.

 

  • Direct Plate Method

o    Add 2 drops of reagent to suspect colonies on an agar plate. Do not flood the plate.

o    Examine for blue colour within 10 seconds.

 

  • Swab Method

o    Dip swab into reagent and then touch colony.

o    Examine for blue colour within 10 seconds.

 

  • Impregnated Oxidase Test Strip Method

o    Scrape some fresh growth from the plate with a disposable loop or stick and rub onto

o    the filter paper.

o    Examine for blue colour within 10 seconds.

 

Positive result development of a blue colour indicates oxidase production

Negative result no blue colour