Question

The bacterium converts nitrites into nitrates.

• A. Pseudomonas
• B. Nitrobacter
• C. Nitrosococcus
• D. Thiobacillus

Hint:

Nitrification occurs in two steps: ammonia to nitrites (by Nitrosococcus) and nitrites to nitrates (by Nitrobacter), aiding plants in absorbing nitrogen.

Answer 1

The Correct Option is B

To identify the bacterium that converts nitrites into nitrates, let’s examine the role of each bacterium in the nitrogen cycle. The process of converting nitrites (NO₂⁻) to nitrates (NO₃⁻) is called nitrification, specifically the second step of nitrification. Nitrobacter is known for this role, as it oxidizes nitrites into nitrates in soil, aiding plant nutrient absorption. Pseudomonas is typically involved in denitrification, reducing nitrates to nitrogen gas, not the conversion of nitrites to nitrates. Nitrosococcus converts ammonia to nitrites, which is the first step of nitrification, not the second. Thiobacillus is known for sulfur oxidation, unrelated to nitrite-to-nitrate conversion.
Final Answer: The bacterium that converts nitrites into nitrates is Nitrobacter, so the correct option is (2).