Milk is changed into curd by which microorganism?

Options

A. Bacillus Megatherium
B. Acetobacter aceti
C. Xanthomonas citri
D. None of the above

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks which microorganism is responsible for changing milk into curd.

2. **Identifying Options**: The options provided include:
- Bacillus Megatherium
- Acetobacter Aceti
- Zentomona Citri
- None of the above

3. **Analyzing Each Option**:
- **Bacillus Megatherium**: This is a non-pathogenic bacterium that does not convert milk into curd.
- **Acetobacter Aceti**: This bacterium is involved in the production of acetic acid (vinegar) and does not play a role in curd formation.
- **Zentomona Citri**: This is a phytopathogen that affects plants and has no relevance to milk or curd production.

4. **Identifying the Correct Microorganism**: The microorganism that is responsible for converting milk into curd is **Lactobacillus**. This bacterium ferments lactose (the sugar in milk) into lactic acid.

5. **Understanding the Process**: The production of lactic acid lowers the pH of the milk, causing the casein proteins to coagulate, which results in the formation of curd.

6. **Conclusion**: Since none of the options listed (A, B, or C) are correct, the answer to the question is **option D: none of the above**.

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