Classification Of Microorganism

Classification Of Microorganisms

Microorganisms are classified into four groups, bacteria, fungi, protozoa and algae. Other than these four groups there exist a group of organisms called as virus. Viruses are considered to be borderline of living and nonliving things. The reason behind it is, viruses do not have a cellular structure, i.e they lack cytoplasm and other cell organelles . This shows that viruses are nonliving organisms. However, once virus enter into body of other organism, it uses the energy and nutrients of the host cell. This allows them to reproduce and multiply in thousands. This characteristics makes them living. Common diseases such as cold, influenza are caused by viruses. Structure of microorganisms can be unicellular or multicellular . Bacteria is unicellular microorganism whereas, algae and fungi are multicellular.

Home For Microorganisms

Microorganisms are found everywhere in air, in water, in soil, our body, also in body of other animals and plants. These organisms survive in all type of environment from ice cold region to area of hot springs. They survive in deserts, marshy lands and also at bottom of sea. There are some microbes that grow on other organisms like plasmodium which lives in human blood and cause malaria. Moreover, some live freely like amoeba. Also, many microorganisms live in colonies like fungi and bacteria.

Microorganisms As Friend

Microorganisms play an important role in our life. Let’s talk about benefits of microorganisms. You must be enjoying eating idlis and bhaturas. It is because idlis and bhaturas contain curd. Curd inturn contains bacteria called lactobacillus. When curd is added to these food stuff, these bacteria multiply, and during respiration releases CO₂ which make food stuff puffy and soft. Yeast are used to convert natural sugars present in grains like barley, wheat, rice and crushed fruit juices into alcohol. The process of conversions of sugar into alcohol is known as fermentation. Medicines like antibiotics contains microorganisms like bacteria and fungi which kills disease causing microbes. Similarly, microorganisms are also used in vaccines to cure diseases. Bacteria like blue green algae, rhizobium increases the fertility of the soil. Moreover, microorganisms are also used in decomposition of dead matter, thereby keeping surrounding clean.

Microorganisms As Foe

As everything as two sides a good and a bad, even microorganisms have bad side. Microorganisms causing disease are called pathogens. Pathogens enter in our body through air, water and food or by direct contact with infected person. Various air borne diseases and waterborne diseases are caused due to transfer of bacteria from infected body to healthy body. For example, Measles, chickenpox, polio, cholera, typhoid are some of air borne and waterborne diseases. Also, there are some animals which carry pathogens and cause diseases in human. Malaria is caused by female anopheles mosquito which carry plasmodium. Not only humans but also animals and plants are infected by disease due to microorganisms.

Preservation Of Food From Microorganisms

Very often microorganisms attack food item and start growing on it. Such food is poisonous to consume. Thus, there is need of food preservation. Here are few methods of food preservation.

• Chemical methods: Chemicals which prevent the growth of microorganism and are therefore called preservatives. Sodium Benzoate and Sodium Metabisulphite are common preservatives used in jams and squashes.
• Preservation by common salt: Common salt is widely used in preservation of meat and fish. It is done by covering meat and fish with dry salt. The layer prevent the growth of bacteria. Moreover, common salt is also used to preserve amla, raw mangoes, tamarind, etc.
• Preservation by oil and vinegar: Oil and Vinegar does not allow bacteria to grow. Vegetables, fruits are preserved by this method.
• Heat and cold treatment: Microorganisms cannot grow in hot and cold surrounding, therefore, boiling of food kills the microorganisms and keeping the food at low temperature environment such as refrigerator prevent their growth.
• Pasteurization: This process is use in the preservation of milk. Milk is heated at about 700 ° C for 15 to 30 seconds and then suddenly cooled and stored. This makes milk free from harmful microbes. Since, this method is discovered by Louis Pasteur, thus, method is known as pasteurization.
• Storage: To prevent growth of microorganisms, dry fruits and vegetables are sold in sealed airtight packets.

This article is helpful for Class 8 Science Chapter 2 Microorganisms: Friend and Foe