Among the following which one is recently discovered non - legume nitrogen fixing bacterium

Options

A. Azotobacter paspali
B. Rhizobium
C. Nitrosomonas
D. Spirillum.

Answer

To solve the question of which is the recently discovered non-legume nitrogen-fixing bacterium among the options provided, we can follow these steps:

### Step 1: Understand the Options
We have four options:
1. Azotobacter paspali
2. Rhizobium
3. Nitrosomonas
4. Spirulum

### Step 2: Analyze Each Option
- **Azotobacter paspali**: This is a free-living nitrogen-fixing bacterium found in the soil. It can independently fix nitrogen from the atmosphere and make it available for plants.

- **Rhizobium**: This bacterium is known for its symbiotic relationship with leguminous plants. It fixes nitrogen but does so in association with the roots of these plants, making it a legume-associated nitrogen fixer.

- **Nitrosomonas**: This bacterium plays a role in the nitrogen cycle by converting ammonia into nitrite. It does not fix nitrogen from the atmosphere.

- **Spirulum**: This is not known to fix nitrogen. It does not participate in nitrogen fixation.

### Step 3: Identify the Correct Answer
From the analysis, the only bacterium that is a free-living nitrogen fixer and not associated with legumes is **Azotobacter paspali**. Therefore, the correct answer is option 1.

### Final Answer
The recently discovered non-legume nitrogen-fixing bacterium is **Azotobacter paspali**.

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