Q: Which equation best represents the hydrolysis of gelatin by gelatinase?

$$\text{Gelatin} + \text{H}_2\text{O} \xrightarrow{\text{gelatinase}} \text{Polypeptides/Amino acids}$$

Question 1

Which enzyme is tested for in the gelatinase test, and what is its primary function?

Accepted Answer

Gelatinase; hydrolyzes gelatin into smaller peptides

Question 2

After incubating a nutrient gelatin tube with a bacterial sample, the tube is refrigerated. The medium remains liquid. What does this indicate about the organism?

Accepted Answer

The organism is gelatinase positive and has hydrolyzed the gelatin.

Question 3

Which of the following bacteria is gelatinase negative according to the study material?

Accepted Answer

Escherichia coli

Question 4

What is the expected result for Bacillus subtilis in the casein hydrolysis test?

Accepted Answer

Casein positive

Question 5

Why does the nutrient gelatin medium remain liquid after refrigeration if the organism is gelatinase positive?

Accepted Answer

Gelatin has been hydrolyzed and cannot solidify at low temperatures.

Question 6

Which of the following is a correct interpretation of a negative gelatinase test?

Accepted Answer

The medium solidifies after refrigeration, indicating no gelatin hydrolysis.

Question 7

If a bacterium is both gelatinase and caseinase positive, which of the following results would you expect in their respective tests?

Accepted Answer

Liquid medium after refrigeration in gelatin test and clear zone around growth in casein test

Question 8

Which equation best represents the hydrolysis of gelatin by gelatinase?

Accepted Answer

$$	ext{Gelatin} + 	ext{H}_2	ext{O} \xrightarrow{	ext{gelatinase}} 	ext{Polypeptides/Amino acids}$$

Question 9

A clinical isolate is tested for gelatinase activity. The medium remains solid after refrigeration. What is the most likely conclusion?

Accepted Answer

The organism does not produce gelatinase and cannot hydrolyze gelatin.

Question 10

Which of the following organisms is caseinase positive according to the study material?

Accepted Answer

Bacillus subtilis

Question 11

A student performs a gelatinase test and observes that the medium is liquid after refrigeration. They also perform a casein hydrolysis test and see a clear zone around the bacterial growth. Which enzymes are present?

Accepted Answer

Both gelatinase and caseinase

Question 12

Which of the following statements best explains why gelatinase activity is clinically significant?

Accepted Answer

Gelatinase allows pathogens to degrade host connective tissue, aiding in invasion.

Question 13

Which result would you expect for Pseudomonas aeruginosa in the casein hydrolysis test?

Accepted Answer

Casein positive

Question 14

If a bacterium is gelatinase negative but caseinase positive, what would you expect after refrigeration of the gelatin medium and observation of the casein plate?

Accepted Answer

Solid gelatin medium and clear zone on casein plate

Question 15

Which of the following is NOT a correct interpretation of the gelatinase test?

Accepted Answer

Blue color change indicates gelatinase activity.

Question 16

Which organism is both gelatinase positive and caseinase negative according to the study material?

Accepted Answer

Serratia marcescens

Question 17

What is the role of refrigeration in the gelatinase test?

Accepted Answer

To determine if gelatin has been hydrolyzed by observing whether the medium solidifies

Question 18

Which of the following best describes the difference between the gelatinase and caseinase tests?

Accepted Answer

Gelatinase test uses nutrient gelatin to detect gelatin hydrolysis; caseinase test uses milk agar to detect casein hydrolysis.

Question 19

A patient sample is tested for gelatinase and caseinase. The results are negative for both. Which of the following is most likely true?

Accepted Answer

The organism cannot hydrolyze either gelatin or casein.

Gelatinase and Caseinase Tests in Microbial Metabolism

Study Guide - Practice Questions

Study Guide - Flashcards