Question

Given below are two statements:
Statement (I): Catalase test is used to test the purity of dairy starters.
Statement (II): Catalase is an enzyme found in anaerobic bacteria only.
In light of the above statements, choose the most appropriate answer from the options given below.

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

All lactic acid starter cultures are catalase-negative. The development of bubbles (positive result) during a starter culture test indicates contamination by catalase-positive aerobic bacteria.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The catalase test detects the presence of the enzyme catalase, which catalyzes the decomposition of hydrogen peroxide (\(\text{H}_2\text{O}_2\)) into water and oxygen gas.

Step 2: Detailed Explanation:
Let us analyze both statements:

• Statement (I): Dairy starter cultures (lactic acid bacteria like Lactococci and Lactobacilli) are characteristically catalase-negative. If a starter culture is contaminated with common aerobic or facultative contaminants (such as Staphylococci, Bacillus, or coliforms), which are catalase-positive, the addition of hydrogen peroxide will produce gas bubbles. Thus, the catalase test is used to test starter culture purity. This statement is Correct.

• Statement (II): Catalase is an enzyme primarily found in aerobic and facultatively anaerobic organisms, which use oxygen and must neutralize toxic reactive oxygen species like hydrogen peroxide. Strictly anaerobic bacteria lack catalase. Thus, this statement is Incorrect.

Step 3: Final Answer
Statement (I) is correct, but Statement (II) is incorrect.