Oxidase Test
Principle
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Cytochrome oxidase is an enzyme found in some bacteria that transfers electrons to oxygen, the final electron acceptor in some electron transport chains.
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Presence of cytochrome oxidase can be detected through the use of dyes such as P-phenylenediamine dihydrocholide, that substitute for oxgen as artificial electron acceptors.
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In reduced state the dye is colorless; however in the presencec of cytochrome oxidase and atmospheric oxygen, the dye is oxidised ,forming indophenol blue.
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This test is most helpful in screening colonies suspected of being one of the Enterobacteriaceae (all negatives) and other genera such as Aeromonas,Pseudomonas,Neisseria ,Campylobacter and Pasteurella(positive)
Methodology
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Inoculate a nutrient agar plate with the test organism.
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Incubate at 370C for 24 hours.
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Transfer the colony with a platinum loop or glass rod to a wet filter paper containing oxidase reagent (tetra methyl para phenylene diamine hydrochloride) or commercial oxidase disc.
Result
![Oxidase Oxidase](http://14.139.56.154:82/file.php/183/Oxidase_test.JPG)
Oxidase test
Control
- Positive : Pseudomonas aeruginosa
- Negative : Enterobacteriaceae
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Last modified: Monday, 4 June 2012, 7:56 AM