Which of the following bacteria convert nitrites to nitrates

Options

A. Pseudomonas
B. Nitrobacter
C. Nitrococcus
D. Thiobacillus

Answer

To solve the question "Which of the following bacteria convert nitrites to nitrates?", we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Terms**:
- Nitrites (NO2-) and Nitrates (NO3-) are both nitrogen compounds. It is important to know the difference between them.

2. **Identify the Process**:
- The conversion of nitrites to nitrates is part of the nitrogen cycle, which involves various bacteria.

3. **Recall the Bacteria Involved**:
- In the nitrogen cycle, certain bacteria are responsible for different transformations of nitrogen compounds.
- Ammonia (NH3) is converted to nitrites (NO2-) by bacteria like Nitrosomonas and then nitrites are converted to nitrates (NO3-) by another type of bacteria.

4. **Identify the Correct Bacteria**:
- The bacteria that convert nitrites to nitrates are known as Nitro-bacter. This is the key bacteria we are looking for in this question.

5. **Eliminate Incorrect Options**:
- Pseudomonas and Thio-bacillus are involved in denitrification, which is the conversion of nitrates back to atmospheric nitrogen (N2), and thus are not responsible for converting nitrites to nitrates.
- Nitro-coccus is involved in nitrogen fixation, not in the conversion of nitrites to nitrates.

6. **Conclusion**:
- Based on the information gathered, the correct answer to the question is **Nitro-bacter**.

### Final Answer:
The bacteria that convert nitrites to nitrates is **Nitro-bacter**.