Catalase Test Open the Virtual Lab and click the “New” button. Select the “Media

Question

Catalase Test

Open the Virtual Lab and click the “New” button. Select the “Media Tests 6” unknown from the “Exercise Topic and Subgroup” list. Give the identifier “MT6”. Review the Case Study and record the Gram stain results. Based on shape and grouping, what would you predict to be the genus of this organism?

From the “View” list, select “Catalase Video”. Appearing will be a viewer where you can watch the addition of 3% hydrogen peroxide to a smear of fresh growth on a microscope slide. The video can be replayed if needed. Based on the information provided above, is this organism catalase positive or negative? (Circle or highlight)

Positive                                  Negative

What evidence supports your interpretation?

What would the video look like if the result was opposite to that portrayed in the video?

Record the results in the software and watch the Identification Matrix for any changes. Click on View and select Lab Report to determine how many species of bacteria were unknown based on the result you recorded. How many bacterial species were eliminated?

Would strict aerobes or strict anaerobes be more likely to possess catalase? Explain your reasoning.

Explanation / Answer

I couldn't find virtual lab to answer the first part of your question. However, i can answer the last part regarding possessing catalase.

Producing catalase is one of the characteristic of strict aerobes. The enzyme catase is produced by those bacteria that respire using oxygen. The role of this enzyme is to protect the bacteria from the toxic by-products of oxygen metabolism. Strict anaerobes do not produce catalase. Therefore, the catalase test can be used to differentiate strict aerobes and strict anaerobes. Staphylococci is a catalase positve bacteria indicating that it is a strict aerobe. Streptococci is a catalase negative bacteria indicating that it is a strict anaerobe.

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