Specifically, it's a group of bacteria called Lactobacillus acidophilus. These bacteria convert lactose (milk sugar) into lactic acid, which gives curd its characteristic sour taste and thick texture.

Here's why Lactobacillus is so useful:

* Digestive health: Lactobacillus helps improve digestion and promotes the growth of good bacteria in the gut.

* Nutrient absorption: It aids in the absorption of calcium and other nutrients.

* Antimicrobial properties: It produces substances that inhibit the growth of harmful bacteria.

So, next time you enjoy a bowl of curd, remember the tiny heroes working hard to make it delicious and beneficial for your health!