Streptococcus lactis is responsible for
(a) Conversion of molasses into alcohol
(b) Conversion of milk into curd
(c) Tanning of leather
(d) Flavouring the leaves of tea and tobacco

Hint: The strain of Streptococcus mentioned here is lactis. This particular strain is useful in creating products related to milk.

Complete answer:
- Streptococcus lactis is a bacteria used in the manufacturing of various milk-based products like curd, buttermilk, cheese, etc. It is the most important microorganisms in the dairy industry.
- When S. lactis is added to milk, the bacteria produce enzymes which use the lactose present to convert it into ATP and lactic acid is produced as a byproduct. The lactic acid curdles the milk, thus giving it the consistency and texture of curd.
- S. lactis is a Gram-positive bacteria. It is spherical in shape and does not form spores. It is non-motile.
So, the correct answer is ‘conversion of milk into curd’.

Additional Information:
- This microorganism is known as a ‘starter culture’ where it is used to begin the fermentation process of a product, in this case, it is milk.
- The lactic acid produced by the bacteria also lowers the pH of milk which inhibits the growth of many other pathogenic microorganisms.
- Other lactic acid-producing bacteria include Lactobacillus and Lactococcus species.
- This bacteria is also used in the fermentation of soy milk, some bread, and pickled vegetables.



Note:
- Streptococcus lactis is now commonly known as Lactococcus lactis.
- This bacteria is also used for producing other fermented products such as cheeses, sour cream, kefir, buttermilk, nisin, etc.