Which of the following is correct

Options

A. Cyanobacteria makes mycorhiza which absorbs phosphate from soil
B. Azotobacter is symbiotic nitrogen fixing bacteria
C. In paddy field, cyanobacteria is used to decrease soil microbes
D. Methanobacterium feed cellulose in anaerobic condition

Answer

To determine which of the statements provided is correct, we will analyze each option based on the information given in the video transcript.

### Step-by-Step Solution:

1. **Analyze Option 1**:
- The statement claims that cyanobacteria makes mycorrhiza which absorbs phosphate from the cell.
- **Correction**: Cyanobacteria (blue-green algae) do not form mycorrhiza. Mycorrhiza is a symbiotic association between fungi and the roots of higher plants, where fungi absorb nutrients (like phosphate) from the soil and provide them to the plant. Therefore, this statement is **incorrect**.

2. **Analyze Option 2**:
- The statement claims that agedobacteria is a symbiotic nitrogen-fixing bacteria.
- **Correction**: Agedobacteria is not a symbiotic nitrogen-fixing bacteria; it is a free-living nitrogen-fixing bacterium. Thus, this statement is also **incorrect**.

3. **Analyze Option 3**:
- The statement claims that pedifield (rice field) cyanobacteria leads to a decrease in soil microbes.
- **Correction**: The presence of cyanobacteria (like azolla) in rice fields does not decrease soil microbes; instead, it contributes positively to nitrogen fixation and productivity. Therefore, this statement is **incorrect**.

4. **Analyze Option 4**:
- The statement claims that Methanobacterium feeds on cellulose in low-anaerobic conditions.
- **Correction**: Methanobacterium is indeed a type of methanogen that thrives in anaerobic conditions and digests cellulose to produce methane (biogas). This statement is **correct**.

### Conclusion:
- The only correct statement among the options provided is **Option 4** regarding Methanobacterium.