Milk bacterium is

Options

A. Acetobacteria
B. Diplococcus
C. Lactobacillus
D. Streptobacillus.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the type of bacterium commonly referred to as the "milk bacterium."

2. **Identifying the Options**: The options provided are:
- A) Acetobacteria
- B) Diplococcus
- C) Lactobacillus
- D) Streptobacillus

3. **Analyzing Each Option**:
- **Acetobacteria**: This group of bacteria is primarily involved in the fermentation of alcohol into acetic acid (vinegar) and is not specifically known for its role in milk.
- **Diplococcus**: This refers to a genus of bacteria that are spherical and typically found in pairs. They are not specifically associated with milk.
- **Lactobacillus**: This is a genus of bacteria that is well-known for its role in the fermentation of lactose (the sugar found in milk) into lactic acid. It is commonly used in the production of yogurt and other dairy products.
- **Streptobacillus**: This refers to rod-shaped bacteria that are typically found in chains. They are not specifically associated with milk fermentation.

4. **Conclusion**: Based on the analysis, Lactobacillus is the bacterium that is commonly associated with milk, as it ferments lactose and is used in the production of yogurt and curd.

5. **Final Answer**: Therefore, the correct answer is **C) Lactobacillus**.

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