Question

Anaerobic microbes cannot survive in the presence of oxygen due to lack of:

• A. Taq polymerase
• B. Superoxide dismutase
• C. ATP synthase
• D. Oxidoreductase

Hint:

Remember:
• Superoxide dismutase (SOD) \(\rightarrow\) Protects against superoxide radicals
• Catalase \(\rightarrow\) Breaks down hydrogen peroxide \[ \text{Obligate anaerobes usually lack SOD and catalase} \]

Answer 1

The Correct Option is B

Concept: Oxygen metabolism generates toxic reactive oxygen species (ROS) such as: \[ \text{Superoxide radicals } (O_2^-) \] Aerobic organisms possess protective enzymes that detoxify these harmful molecules:
• Superoxide dismutase (SOD)
• Catalase
• Peroxidase Obligate anaerobes generally lack superoxide dismutase and related detoxifying enzymes, making oxygen toxic to them.

Step 1: Understanding oxygen toxicity in anaerobes. In the presence of oxygen: \[ O_2 \rightarrow O_2^- \] (superoxide radical formation) Superoxide dismutase converts toxic superoxide radicals into less harmful compounds: \[ 2O_2^- + 2H^+ \rightarrow H_2O_2 + O_2 \] Anaerobic microbes lack sufficient superoxide dismutase activity, so toxic radicals accumulate and damage cellular components. Therefore: \[ \boxed{\text{Anaerobic microbes cannot survive due to lack of superoxide dismutase}} \]

Step 2: Eliminating the incorrect options.
• Option (A): Taq polymerase is a thermostable DNA polymerase used in PCR and is unrelated to oxygen tolerance.
• Option (C): ATP synthase is involved in ATP production and is present in many organisms.
• Option (D): Oxidoreductases are a broad class of enzymes and not specifically responsible for oxygen detoxification. Hence, the correct answer is Superoxide dismutase. \[ \boxed{Oxygen~tolerance \Rightarrow \text{Presence of SOD}} \]