Which one of the following is not used in the production of yoghurt

Options

A. Acetobacter aceti
B. Streptococcus thermophilus
C. Streptococcus lactis
D. Lactobacillus bulgaricus

Answer

To determine which of the following options is not used in the production of yogurt, we will analyze each option based on their roles in yogurt production.

### Step-by-Step Solution:

1. **Understanding Yogurt Production**: Yogurt is produced through the fermentation of milk. The process involves specific bacteria that convert lactose (milk sugar) into lactic acid, which gives yogurt its characteristic sour taste and thick texture.

2. **Identifying Key Bacteria**: The main bacteria used in yogurt production are:
- **Streptococcus thermophilus**
- **Streptococcus lactis**
- **Lactobacillus bulgaricus**

3. **Evaluating the Options**:
- **Option A: Acetobacter aceti**: This bacterium is primarily involved in the production of vinegar from acetic acid and is not used in yogurt production.
- **Option B: Streptococcus thermophilus**: This bacterium is commonly used in yogurt production.
- **Option C: Streptococcus lactis**: This bacterium is also used in yogurt production.
- **Option D: Lactobacillus bulgaricus**: This is another bacterium used in yogurt production.

4. **Conclusion**: Since Acetobacter aceti is not involved in the production of yogurt, the correct answer is **Option A: Acetobacter aceti**.

### Final Answer:
**Acetobacter aceti** is not used in the production of yogurt.

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