The most common food item that are curd, and yoghurt contain Lactic Acid Bacteria (LAB) of Lactobacillus species. Curd is formed by adding a small amount of curd to milk, which acts as a starter. Microbes present in starter multiply at suitable temperature and convert milk into curd.

Acids released by LAB during the growth coagulate and partially digest milk protein, casein thus increases the digestibility of milk protein.

Application of LAB

(i) Improves nutritional quality of milk by increasing vitamin- $\mathrm{B}_{12}$.

(ii) Checks disease-causing microbes in stomach.