How are bacteria useful to human beings?

The bacteria are useful to human beings in following way:

1. Saprophytic bacteria decompose excretory products and the dead remains of plants and animals into simpler substances. Therefore, they clear the earth of all waste. That is why they are called decomposers or nature’s scavengers.
2. Bacteria along with certain fungi play an important role in maintaining soil fertility.
3. Some bacteria live in the roots of leguminous plants such as peas and beans. They absorb atmospheric nitrogen and convert it into nitrates, which are used by plants.
4. The digestive tract of herbivorous animals contains bacteria which helps to digest cellulose.
5. The manufacturing of vinegar, curd and cheese involves fermentation by bacteria. It is also used in production of tea, coffee, lactic acid, citric acid and alcohol etc.
6. Tanning of leather and retting of fibres are done by the action of bacteria.
7. Certain medicines such as antibiotics and vitamin B complex tablets are manufactured with the help of bacteria.