Microbiology - 009 - Oxidase Test

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The oxidase test determines whether or not a bacterial isolate produces the enzyme cytochrome c oxidase, which is an  important part of the electron transport chain. Make sure you have the organism of interest in a fresh, pure culture.  Then, use a toothpick or a sterile loop or needle to transfer a small amount of bacteria to a piece of filter paper. Obtain a new dropper of oxidase reagent and squeeze it gently near the middle to break the glass ampule inside. Use the dropper to add a drop of oxidase reagent to the bacteria on the filter paper, and look for the appearance of blue or  purple spots – a positive result. After 15 seconds, if no color appears, the test is negative for the presence of cytochrome oxidase. Check the results quickly; waiting more than 15 seconds can give a false positive result. Throw away the dropper of oxidase reagent when done, and dispose of the filter paper and any toothpicks in a biohazard bin.

The oxidase test determines whether or not a bacterial isolate produces the enzyme cytochrome c oxidase, which is an important part of the electron transport chain.

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