The microbial source for citric acid is

Options

A. Aspergillus niger
B. Acetobacter acetic
C. Clostridium butylicum
D. Lactobacillus acidophilus

Answer

To determine the microbial source for citric acid, we will analyze the given options one by one.

1. **Aspergillus niger**:
- This is a type of fungus known for its ability to produce citric acid.
- The production of citric acid occurs through anaerobic fermentation, which means it takes place in the absence of oxygen.
- Aspergillus niger is indeed used in the industrial production of citric acid, making this option correct.

2. **Acetobacter acetic**:
- This bacterium is primarily involved in the production of acetic acid, which is the main component of vinegar.
- It converts ethanol (found in wine) into acetic acid, but it does not produce citric acid.
- Therefore, this option is incorrect.

3. **Clostridium butylicum**:
- This is a gram-positive bacterium that is known for producing butyric acid.
- It does not have a role in the production of citric acid.
- Thus, this option is also incorrect.

4. **Lactobacillus acidophilus**:
- This bacterium is commonly found in the human intestine and is known for producing lactic acid.
- It is not involved in the production of citric acid.
- Hence, this option is incorrect as well.

After evaluating all the options, we conclude that the correct microbial source for citric acid is **Aspergillus niger**.

### Final Answer:
The microbial source for citric acid is **Aspergillus niger**.

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