Bacterium useful in dairy and curdling of milk is :

Options

A. Micrococcus
B. Streptococcus lactis
C. Lactobacillus
D. Diplococcus pneumoniae

Answer

To solve the question regarding which bacterium is useful in dairy and curdling of milk, we can follow these steps:

### Step 1: Understand the Question
The question asks for a specific bacterium that is involved in the dairy industry, particularly in the curdling of milk.

### Step 2: Analyze the Options
We have four options to consider:
1. Micrococcus
2. Streptococcus lactis
3. Lactobacillus
4. Streptococcus pneumoniae

### Step 3: Evaluate Each Option
- **Micrococcus**: This bacterium is primarily known for its role in providing color and flavor to food but is not used for curd production. Therefore, it is not the correct answer.

- **Streptococcus lactis**: While this bacterium is involved in the production of cheese and butter, it is not specifically known for curd production. Thus, it is not the correct answer for this question.

- **Lactobacillus**: This is a well-known bacterium that is crucial for the fermentation process in dairy products. It is specifically effective in curdling milk and producing curd. Therefore, this is the correct answer.

- **Streptococcus pneumoniae**: This bacterium is known for causing diseases and is not involved in food production. Hence, it is not the correct answer.

### Step 4: Conclusion
Based on the evaluation, the bacterium that is useful in dairy and curdling of milk is **Lactobacillus**.

### Final Answer:
**Lactobacillus**

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