Microorganisms or a microbe is microscopic organism. The study of microorganisms is called microbiology. There are various microorganisms types like bacteria, fungi, archaea, or protists. It doesn't include viruses and prions because they are classified as non-living.

Microorganisms are minute, unicellular organisms that aren't visible to the naked eye. The reason they are called microorganisms is that you can only see them when you use a microscope. These organisms make up around sixty percent of the earth's living matter.

Microorganisms are also known as microbes. This term is used to describe several different life forms of different sizes and characteristics.

Microorganisms are organisms that can be harmful as well as helpful. Some microbes can cause severe infections like spoiling food and other items. At the same time, others play an essential role in maintaining an ecological balance.

What are the Major Groups of Microorganisms?

Many different microbes or microorganisms are found in various places, including the human gut and skin. Here are the names of microorganisms:

Bacteria: Bacteria are unicellular, microscopic microorganisms that have no nucleus. Their cell walls are made of peptidoglycan, which has a flagellum. The flagellum is responsible for the locomotion of the bacteria. Bacteria play a vital role in the survival of human beings. They are the ones who are responsible for breaking down nutrients in the digestive system into simpler forms. One of the bacteria, Rhizobium, is responsible for nitrogen fixation. It is also used for making antibiotics and can be used in agriculture as a pesticide.

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Fungi: Fungi can be unicellular or multicellular, with walls that are made of chitin. They are heterotrophic and cannot make their food. Fungi comprise membrane-bound organelles. Some of the primary forms of fungi are mushrooms, yeasts, and mould. They decompose dead plants and animals and extract nutrients from them. A few of the fungi are harmful as they can cause a fungal infection like ringworms. At the same time, others are significant as they help in making penicillin.

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Viruses: They are the link or the connection between the living and the non-living. Viruses are non-cellular microorganisms that are composed of protein, nucleic acids, and lipids. These contain the core of the nucleotides, which is surrounded by a protein coat that can invade the living cells. Viruses are active inside the host cells and keep reproducing inside themselves by infecting the living cells.

Protists: Like the other microorganisms, protists are unicellular and microscopic organisms that are not plants or animals. Usually, they are either autotrophic or heterotrophic. Protists reproduce through binary fusion or budding. They supply humans with oxygen and recycle essential nutrients and make them available to other life forms.

Archaea: These unicellular microorganisms have a similar structure to bacteria. However, their cell wall is different from bacteria and contains unique lipids, which helps them survive in extreme conditions. Archaea are found in the human gut and skin.

Characteristics of Microorganisms

There are many types of microorganisms. Some characteristics are similar in some of them. Here are some of the features of microorganisms:

When microorganisms are used in the large-scale production of alcohol, wine, and vinegar, it can be harmful.
Some microorganisms are known as pathogens that can cause diseases in humans, plants, and animals.
Some organisms can spoil the leather, food, and clothing.

Importance of Microorganisms

Microorganisms are present in almost all the places on earth. Despite their minute size, they are essential for the maintenance of life on this planet. Every organism has different activities, and they each have another way to influence life.

Some of them are useful and helpful, like the microorganism, which helps fix atmospheric nitrogen into biologically functional forms. This helps in the formation of curd and recycling of dead material by degrading it into simpler substances.

Uses of Microorganisms in Our Daily Life

There are many uses of microorganisms for use in many ways. Here are some ways in which we use microorganisms in our daily lives:

Production of Dairy Products: Bacteria helps in the fermentation that helps make different forms of dairy products like curd, butter, cheese and buttermilk. Streptococcus is the type of bacteria that is used in the commercial production of dairy products.

Bread Baking: A species of Streptococcus is added to the dough before you start making bread to bring about the fermentation.

Organic Acids: Fungi is used in the preparation of many organic acids. Rhizopus and Penicillium are two fungi used in the fermentation of fruits and sugar-containing syrups. The acids derived and manufactured exploiting fungi are acetic acid, citric acid, lactic acid, and gluconic acid.

Fertility of Soil: Microorganisms play an essential role in maintaining the fertility of the earth. They are helpful in the composting process that in turn forms manure. When microorganisms are present in the soil, they help the ground aerate better and enrich the soil with nitrates and other essential nutrients, which allow the crops to have an abundant harvest.

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FAQs on Microorganisms: Key Groups, Roles, and Uses

1. What are the major groups of microorganisms as per the CBSE syllabus?

Microorganisms are broadly classified into five major groups. Each group has unique characteristics:

Bacteria: These are single-celled prokaryotic organisms. They can be found everywhere and exist in various shapes like rod, spherical, and spiral.
Fungi: These are eukaryotic organisms that include yeasts, moulds, and mushrooms. They are saprophytic or parasitic and play a key role in decomposition.
Protozoa: These are single-celled eukaryotes, which are mostly aquatic and motile. Examples include Amoeba and Paramecium.
Algae: These are simple, plant-like organisms that perform photosynthesis. Examples include Chlamydomonas and Spirogyra.
Viruses: These are microscopic infectious agents that can only replicate inside the living cells of other organisms.

2. What are some important examples of how microorganisms are used in our daily lives?

Microorganisms are incredibly useful and have numerous applications in our daily lives, particularly in:

Food Production: Bacteria like Lactobacillus are essential for making curd from milk. Yeast, a fungus, is used in baking bread and cakes through the process of fermentation.
Commercial Production: Yeast is used on a large scale to produce alcohol, wine, and acetic acid (vinegar).
Medicine: Antibiotics like penicillin are derived from fungi and bacteria to treat infections. Vaccines are produced using weakened or dead microbes to build immunity.
Agriculture: Certain bacteria and blue-green algae enrich the soil by fixing atmospheric nitrogen, acting as natural bio-fertilisers.

3. How are microorganisms harmful to humans, plants, and animals?

While many microorganisms are beneficial, some are harmful and are called pathogens. They can cause harm in several ways:

Human Diseases: Pathogens like bacteria and viruses cause communicable diseases such as cholera, typhoid, the common cold, and polio.
Animal Diseases: Microbes can cause serious diseases in animals. For example, anthrax is a dangerous bacterial disease affecting both humans and cattle.
Plant Diseases: Many plant diseases like citrus canker (caused by bacteria) and rust of wheat (caused by fungi) reduce crop yields.
Food Spoilage: Microorganisms like fungi and bacteria can grow on food items and spoil them by producing toxic substances, leading to food poisoning.

4. What is fermentation and what are its key applications?

Fermentation is a metabolic process where microorganisms like yeast and bacteria convert complex carbohydrates, such as sugar, into simpler compounds like alcohol or acid in the absence of oxygen. This process releases energy. Its key applications include making bread, where yeast produces carbon dioxide that makes the dough rise, and the commercial production of alcoholic beverages and vinegar.

5. Why are viruses considered to be on the borderline between living and non-living things?

Viruses are considered unique because they exhibit characteristics of both living and non-living entities. They are considered non-living outside a host body because they are inert and can be crystallised like salt or sugar. However, once they enter a living host cell, they take over its machinery to replicate, which is a key characteristic of living organisms. This dual nature places them on the borderline of life.

6. How do microorganisms play a crucial role as environmental cleaners?

Microorganisms, particularly bacteria and fungi, act as nature's decomposers. They break down complex organic waste from dead plants, animals, and faecal matter into simpler, non-toxic, and usable substances. This process of decomposition not only cleans up the environment by removing waste but also recycles vital nutrients back into the soil, making them available for plants to use again. This entire process prevents the accumulation of dead organic matter and maintains ecological balance.

7. What is the fundamental difference between an antibiotic and a vaccine?

The fundamental difference lies in their function and mechanism:

An antibiotic is a medicine used to treat an existing bacterial infection. It works by killing the bacteria or inhibiting their growth inside the body.
A vaccine is a biological preparation used to prevent a disease. It contains a weakened or inactive form of the pathogen, which stimulates the immune system to produce antibodies without causing the disease, providing long-term immunity against future infections.

8. How does the process of nitrogen fixation by microorganisms benefit agriculture?

Nitrogen fixation is a critical process for agriculture. Certain bacteria, like Rhizobium found in the root nodules of leguminous plants, and some blue-green algae can convert unusable atmospheric nitrogen into usable forms like nitrates and nitrites in the soil. This natural process significantly increases soil fertility. As a result, farmers can rely less on artificial nitrogen fertilisers, making agriculture more sustainable and cost-effective while ensuring healthy crop growth.