Which of the following reaction is performed by nitrifying bacteria?

Options

A. `N_(2) to NH_(3)`
B. `NH_(3) to NO_(3)`
C. Amino acid `to NH_(3)`
D. `NO_(3)^(-) to N_(2)`

Answer

To determine which reaction is performed by nitrifying bacteria, we will analyze the options provided and identify the correct one.

### Step-by-Step Solution:

1. **Understanding Nitrifying Bacteria:**
Nitrifying bacteria are a group of bacteria that play a crucial role in the nitrogen cycle. They are primarily responsible for the conversion of ammonia into nitrates.

2. **Analyzing the Options:**
- **Option 1:** Conversion of nitrogen into ammonia.
- This process is known as nitrogen fixation and is performed by nitrogen-fixing bacteria, not nitrifying bacteria. Therefore, this option is incorrect.

- **Option 2:** Conversion of ammonia into nitrate.
- This is the correct reaction performed by nitrifying bacteria. The process involves two steps:
- First, ammonia (NH₃) is converted into nitrite (NO₂⁻) by bacteria such as Nitrosomonas.
- Then, nitrite is further converted into nitrate (NO₃⁻) by bacteria such as Nitrobacter.
- Thus, this option is correct.

- **Option 3:** Conversion of amino acids into ammonia.
- This process is related to the breakdown of organic matter and is not a function of nitrifying bacteria. This option is incorrect.

- **Option 4:** Conversion of nitrate into atmospheric nitrogen.
- This reaction is performed by denitrifying bacteria, not nitrifying bacteria. Denitrifying bacteria convert nitrates back into nitrogen gas (N₂), making this option incorrect.

3. **Conclusion:**
The correct answer is **Option 2: Conversion of ammonia into nitrate**, which is the primary function of nitrifying bacteria.