Exercise 5-5: Oxidation Test

6. Explain the reaction that gives the purple color. (2)

The oxidase test detects the presence of a cytochrome oxidase system that will catalyse the transport of electrons between electron donors in the bacteria and a redox dye- tetramethyl-p-phenylene-diamine. The dye is reduced to deep purple color.

1. Oxidase test is used to identify bacteria containing the respiratory enzyme a. Catalase b. Cytochrome C oxidase c. Superoxide dismutase d. Cytochrome b oxidase e. Cytochrome o oxidase

b. Cytochrome C oxidase

3.) What reagent is included in the dry slide to detect the positive color reaction? a. Nitrate reagent A and B b. Ferric chloride c. Oxidase reagent d. Zinc powder e. Methyl red f. VP reagent A g. VP reagent B

c. Oxidase reagent

5. A positive result (purple color within 20 sec) indicates that the bacterium has the enzyme ________________

Cytochrome C oxidase

4. If you observe a purple color after 1 minute, this is considered a positive result. a. True b. False

b. False (supposed to be after 20 seconds)