Questions: The oxidase test is used to classify bacteria based on the presence or absence of cytochrome oxidase enzyme in an unknown organism. Here are the results of your oxidase test. What can you conclude? The oxidase test on the unknown bacterium is positive. The oxidase test result cannot be determined from this swab. The oxidase test on the unknown bacterium is negative. The oxidase test on the unknown bacterium is neutral.

The answer is the first one: The oxidase test on the unknown bacterium is positive.

Explanation for each option:

1. The oxidase test on the unknown bacterium is positive.

   • This is correct if the test result shows a color change (usually to dark blue or purple), indicating the presence of cytochrome oxidase enzyme.

2. The oxidase test result cannot be determined from this swab.

   • This would be correct if there was no visible reaction or if the test was inconclusive, but the question states a positive result.

3. The oxidase test on the unknown bacterium is negative.

   • This is incorrect because a negative result would show no color change, indicating the absence of the enzyme.

4. The oxidase test on the unknown bacterium is neutral.

   • This is not a standard result for an oxidase test, as it typically yields either positive or negative results.

In summary, a positive oxidase test indicates the presence of cytochrome oxidase enzyme in the bacterium.