Bacteria which directly convert atmospheric nitrogen into nitrogen compounds are called

Options

A. Denitrifying bacteria
B. Putrefying bacteria
C. Nitrogen fixing bacteria
D. Nitrifying bacteria

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the type of bacteria that can directly convert atmospheric nitrogen into nitrogen compounds.

2. **Identifying the Options**: The options provided are:
- D-nitrifying bacteria
- Putrifying bacteria
- Nitrogen-fixing bacteria
- Nitrifying bacteria

3. **Analyzing Each Option**:
- **D-nitrifying bacteria**: These bacteria convert fixed nitrogen compounds in the soil back into atmospheric nitrogen. They play a role in the nitrogen cycle but do not convert atmospheric nitrogen into compounds. Example: Pseudomonas.

- **Putrifying bacteria**: These bacteria are involved in the decay of organic matter. They do not convert atmospheric nitrogen into nitrogen compounds. Their role is more related to decomposition.

- **Nitrogen-fixing bacteria**: These bacteria are specifically known for converting atmospheric nitrogen (N₂) into ammonia (NH₃), which is a nitrogen compound that plants can utilize. An example is Rhizobium, which forms a symbiotic relationship with legumes.

- **Nitrifying bacteria**: These bacteria convert ammonia into nitrates (NO₃⁻), which are also usable by plants, but they do not convert atmospheric nitrogen directly into nitrogen compounds.

4. **Selecting the Correct Answer**: Based on the analysis, the correct answer is **nitrogen-fixing bacteria**, as they are the ones that directly convert atmospheric nitrogen into nitrogen compounds.

5. **Final Answer**: The bacteria which directly convert atmospheric nitrogen into nitrogen compounds are called **nitrogen-fixing bacteria**.

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