In which food would you find lactic acid bacteria? Mention some of their useful applications.

Explanation

### Step-by-Step Solution:

1. **Identification of Food Containing Lactic Acid Bacteria**:
- Lactic acid bacteria (LAB) are primarily found in fermented foods, with curd (yogurt) being one of the most common sources. The specific type of lactic acid bacteria often found in curd is called *Lactobacillus*.

2. **Production of Curd**:
- The lactic acid bacteria play a crucial role in the fermentation process of milk to produce curd. When a small amount of curd is added to milk, the LAB present in the curd ferments the lactose (milk sugar) into lactic acid. This acidification causes the proteins in milk to coagulate, resulting in the formation of curd.

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