Which bacterium converts milk into curd

🔑Key Points:
Curd or yoghurt is made from milk through the fermentation process.
A wide range of bacteria, including Lactobacillus acidophilus, Lactococcus lactis, Lactococcus lactis cremoris, and others, may be present in curd.
Casein, a type of globular protein, is present in milk.
Lactic acid bacteria and casein undergo a chemical reaction that results in the curd.
Lactobacillus converts milk to curd by producing lactic acid and reducing the pH of the milk.
These bacteria convert the lactose into lactic acid, which imparts the sour taste to curd. 
Milk to curd formation is a slow process.
A curd-forming bacteria takes 5 to 6 hours to change milk into curd.
This change is permanent and irreversible because this curd cannot be converted back into milk.