Question

Which one of the following useful organisms is part of the production of curd/ yogurt?
A. S. thermophilus
B. Lactobacillus bulgaricus
C. Acetobacter aceti
D. Streptococcus lactis

Answer 1

The curd is produced due to the presence of a reaction between lactic acid bacteria and the milk protein casein. When milk sugar or lactose undergoes fermentation, the product obtained is lactic acid. The increase in lactic acid decreases pH and causes the milk to clot, or form the soft gel that is characteristic of yogurt.

Complete step by step answer:Lactobacillus is a genus of Gram-positive, aerotolerant anaerobes or microaerophilic, rod-shaped, non-spore-forming bacteria. They are the main part of the lactic acid bacteria group. They convert sugars to lactic acid. Lactobacillus is also used in some fermented foods like yogurt and in dietary supplements. Lactobacillus is most commonly taken by mouth to treat and prevent diarrhea, including infectious diarrhea and diarrhea linked with the use of antibiotics. Lactobacillus are commensal inhabitants of animal and human gastrointestinal tracts, as well as the human mouth and the vagina. Commercial preparations of lactobacilli are used as probiotics to restore normal flora after the imbalance created by antibiotic therapy.
Lactobacillus is the most common probiotic(live bacteria) found in food such as yogurt, and it is
diverse in its application to maintain human well-being, as it can help treat different types of
diarrhea, some vaginal infections, symptoms of irritable bowel movements, and skin disorders such
as eczema.
Lactobacillus acidophilus and bulgaricus may work by helping the body to maintain normal
consistency of bacteria in the stomach and intestines
So the correct option is B**

Note:Lactobacillus , any of a group of rod-shaped, gram-positive, non-spore-forming bacteria of the family Lactobacillaceae. Similar to other genera in the family, Lactobacillus are characterized by their
ability to produce lactic acid as a by-product of glucose metabolism.