Microorganisms and Us

Microorganisms play an important role in our lives. Let’s study them in detail:

• Used in the making of curd and bread: Curd contains several microorganisms. Of these, the bacterium, Lactobacillus promotes the formation of curd. Bacteria and yeast are also involved in the making of cheese, and pickles and are helpful for fermentation of rice idlis and dosa batter.
• Commercial Use of Microorganisms: Yeast is used for the commercial production of alcohol, wine, and vinegar by the process of Fermentation.
• Medicinal Use of Microorganisms: Antibiotics are produced from bacteria and fungi. Streptomycin, tetracycline, and erythromycin are some of the commonly known antibiotics which are made from fungi and bacteria. Antibiotics are manufactured by growing specific microorganisms and are used to cure a variety of diseases.
• Increasing Soil Fertility: Some bacteria are able to fix nitrogen from the atmosphere to enrich the soil with nitrogen and increase its fertility. These microbes are commonly called biological nitrogen fixers.
• Cleaning the Environment: Microorganisms decompose dead organic waste of plants and animals converting them into simple substances. These substances are again used by other plants and animals. Thus, microorganisms can be used to degrade harmful and smelly substances and thereby clean up the environment.

NCERT Notes for Class 8 Science Chapter-2: Microorganisms: Friend and Foe: Organisms that can be seen only through a microscope are known as Microorganisms or Microbes. These microorganisms are so small in size that they cannot be seen with the unaided eye. Some of these, such as the fungus that grows on bread, can be seen with a magnifying glass. Others cannot be seen without the help of a microscope. That is why these are called microorganisms or microbes. They exist in vast numbers and play vital roles in our lives.

Friends and Foe explain that Microorganisms can be both our friends, providing numerous benefits, or our foes, causing harm and disease. Microorganisms are classified into four major groups. These groups are bacteria, fungi, protozoa, and some algae. Viruses are also microscopic but are different from other microorganisms. Common ailments like colds, influenza (flu) and most coughs are caused by viruses. Serious diseases like polio and chicken pox are also caused by viruses. Diseases like dysentery and malaria are caused by protozoa(protozoans) whereas typhoid and tuberculosis (TB) are bacterial diseases.