Question

Curdling of milk takes place by
A. Streptococcus Iocus
B. Streptococcus thermophilous
C. Lactobacillus
D. All the above

Answer 1

Hint: Curdling of milk takes place by a process called fermentation. It occurs in the absence of oxygen. The curdling of milk is done by a gram-positive rod-shaped bacteria that are an important part of the human microbiota system.

Complete answer: Milk is an excellent source of vitamins, minerals, proteins, fats and carbohydrates. The characteristic white colour of milk is due to the presence of a protein called casein. The carbohydrate present in the milk is lactose “disaccharide” which is also called milk sugar. Lactobacillus bacteria convert milk into curd by the process of fermentation. Fermentation is an anaerobic process, i.e. it occurs in the absence of oxygen. The Lactobacillus bacteria present in the milk uses lactose and multiplies itself and keeps on multiplying until the conditions are favourable. The milk is kept for 8 to 12 hours overnight incubation and after that, it should be frozen to halt the bacterial growth. The lactose present in the milk is utilized by bacteria and converts to lactic acid by an enzymatic reaction. Yoghurt is a fermented product of milk fermentation. Lactobacillus is a gram-positive bacteria. In humans, they are an important component of the microbiota at body sites such as the digestive and the urinary tract.
So, the correct answer is option C.

Note: Curd prevents vagina infections in women, promotes healthy skin and reproductive system. It is beneficial in lowering levels of plaque and gingivitis. It provides relief to those suffering from colon cancer and also relieves constipation, diarrhoea, and inflammatory bowel disease. It also boosts immunity and prevents infections and allergies.