What is the full form of $LAB$?

Which of the following are the main benefits of $LAB$?
$I.$ Increase vitamin-$B_{12}$ amount,thus increasing nutrient quality of milk.
$II.$ Checks disease-causing microbes in the stomach.
Choose the correct option.

Which organism is used to ripen Roquefort cheese?

Study the following flow chart that shows curd formation from milk and select the correct option for $A$ and $B$.
Milk is incubated with curd
$\downarrow$
$LAB$ shows growth in milk
$\downarrow$
Production of .....$A$.....
$\downarrow$
Coagulation and digestion of milk protein
$\downarrow$
Improved nutritional quality by increased ....$B$....

Name a microbe used for the production of Swiss cheese.

Which role is played by Lactobacillus in our stomach?