Microorganisms: Friend and Foe
Science Class Eight
What is a Microorganism?
Living organisms which cannot be seen without using microscope, are called microogranisms. For example bacteria, fungi, protozoa, etc.
They got their name microorganism because of their micro size and cannot be seen with the unaided eye. These living organism are present everywhere. Microorganisms are found in air, in water, in hot water, in cold water, within ice pieces, in soil, in food, on trees, in water, within the body of animals. These microorganisms have unparallel living capacity. These microorganisms can survive in almost every conditions, such as in hot boiling water and even in frozen ice.
Reference: Wiedehopf20 [CC BY-SA 4.0], via Wikimedia Commons
Microorganisms are known as microbes also.
Microorganims are our friend and foe both. Some of the microorganisms or microbes are our friend while some of the microorganisms are our enemy. This means some of the microorganisms are useful to us while some of them are harmful for us.
The study of microorganisms is known as Microbiology.
Classification of Microorganism
According to some special characteristics, microorganisms or microbes are classified mainly into four groups. These four groups are (1) bacteria, (2) fungi, (3)protozoa and (4)some algae. Apart from these viruses are also microscopic living organisms.
Bacteria
Bacteria is a single cell organism. Some bacteria are useful for us while some are harmful and cause of many diseases. Bacteria can be of many shapes, they can be rod shaped, round shape, and spiral shaped. Bacteria were one of the first life forms appeared on the earth.
Staphylococcus, Vibrio cholera, Brucelleae, Caryophanaceae, etc. are name of some bacteria.
Many diseases, such as typhoid, tuberculosis, etc. are caused by bacteria and consequently are called bacterial diseases.
"Bacterium" is singular and "Bacteria" is plural.
The study of bacteria is known as Bacteriology, which is a branch of Microbiology.
Fungi
Fungi can be single cellular and multicellular both types. Fungi is considered an organism more than a plant. Mushroom, yeast, bread mould, etc. are examples of some fungi.
Fungi are heterotrophs, which reproduce and get their nutrition on decomposing organisms. Fungi are called natural decomposer. Fungi get their food by secreting digestive juice of over decaying materials, this digestive juice dissolve the molecules of decaying organism and then fungi absorb the dissolve molecules as their food.
Protozoa
Protozoa are single cellular organisms. Amoeba, paramecium, etc. are some examplea of protozoa. Protozoa may live freely or as a parasite. Dysentery, malaria, etc. are some diseases caused because of protozoa.
Algae
Algae can be seen easily in stagnant water. Algae are considered as plant. Algae may be green and brown or reddish in color. Seaweeds are largest and most complex marine algae. Because of presence of chloroplast, algae perform photoshynthesis. Charophyta, Spirogyra, stoneworts, etc. are examples of some algae.
Virus
Virus are parasites because they feed on other living organisms. Virus multiplies and replicates in the cells of other living organism only. Virus can infect almost all types of life forms including bacteria also. Virus is cause of many diseases. Small pox, Measles, Hepatitis B, AIDS, Common cold, Polio, etc. are diseases caused due to virus. Virus can be spread by air and by animals.
Where do Microorganisms Live?
Microorganism is found everywhere and can survive in almost every condition. Microorganisms can be found ranging from ice cold climate to hot spring and desert to marshy lands. Microorganisms are found even inside the bodies of animals and can grow over the other organisms.
Many microorganisms exist freely in the environment. Many microorganisms, such as amoeba live alone while many, such as fungi and bacteria may live in colonies.
Microorganims and Us
Microorganisms are very much important for us. It can be said that without microorganisms, our life is not possible as they play very important role in our life.
Some of the microorganisms are very useful to us while many are harmful for us. This means some microorganims are our friend while many are our enemy.
Friendly Microorganisms
Many microorganisms are very much useful to us, means they are our friend.
Yeast, which is a type of fungi, is used to make bread and cake.
Yeast is used in the production of alcohol right from ancient time. Fermentation takes place when yeast is put in the fruit juice. Yeast make doe prepared for making of bread soft.
Microorganisms are used to clean environment. Microorganism decomposes organic waste such as vegetable peel, remains of animals, etc and convert them into harmless substances.
Microorganisms are used in making of medicines and enhance soil fertility by fixing of nitrogen.
Making of Curd
A bacteria, called lactobacillus converts milk into curd. To covert milk into curd, a small amount of curd is mixed into milk. One of the microorganisms called lactobacillus found in curd multiplies in milk and coverts the milk into curd.
Commercial Use of Microorganisms
Microorganisms is used for the commercial production of alcohol, wine, and vinegar, etc. Yeast is used for the commercial production of alcohol and wine. Yeast converts sugar present in barley, wheat, rice, and fruit juices, into alcohol. For production of alcohol and wine fruit juice is left for many days at hot place after introducing small amount of yeast in them. This yeast replicates and converts sugar present in fruit juice into alcohol. However, fruit juice can be converted into alcohol and wine even without introducing yeast in them.
The process conversion of fruit juice into alcohol by microorganisms is called Fermentation.
Discovery of Fermentation
Louis Pasteur, who was a French Scientist, discovered fermentation in the year of 1857. Louis Pasteur discovered the process to preserve milk also. In his honour the process to preserver milk is called the Pasturisation.
Medicinal Use of Microorganisms
The medicines produced with the help of microorganisms are called Antibiotics. These medicines, antibiotics destroy or stop the growth of infectious bacteria. Since these medicines act against bacteria, thus are called antibiotics (anti + bacteria). Antibiotics come in the form of tablets, syrup and injections, which are given according to need to the sick people. These days a number of antibiotics are available in the market. Steptomycin, tetracyclin, cloxacyclin, erythomycin, etc. are the name of some antibiotics available in the market.
These days many types of antibiotics are manufactured using bacteria and fungi. These antibiotics are manufactured by growing specific microorganisms and are used to cure variety of diseases.
Antibiotics are also mixed with the feed of livestock and poultry to prevent microbial infections in animals. Antibiotics are also used to control many plant diseases.
Caution while taking Antibiotics
(a) Antibiotics should not be taken without the advice of a qualified doctor.
(b) One should must complete the prescribed course of antibiotics.
(c) Antibiotics must not be taken unnecessarily, otherwise it may kill the useful bacteria of the body.
Discovery of Antibiotics
Sir Alexander Fleming, who was a British Scientist, discovered Antibiotics in 1929, while working on a culture of disease causing bacteria. He suddenly found that the spoers of a little green mould in one of his culture plates and observed that the presence of those moulds prevented the growth of bacteria.
Later he prepared the penicillin, an antibiotic from those moulds.
Sir Alexander Fleming honoured with Noble Prize for the discovery of antibiotics.
Vaccine
Whenever any harmful microorganism enter in our body, our body produce antibodies. These antibodies destroy and stop the growth of the foreign as well internal harmful microorganisms.
The body also remembers how to fight the microbe if it enters again. Based on this theory of mechanism of body vaccines are prepared. If dead or weakened microbes are introduced in a healthy body, the body fights and kills them by producing suitable antibodies. The antibodies so produced remain in the body and protect us from disease causing microbes.
Particular type of dead or weakened microbes are introduced in our body as a vaccine, as type of medicine, to enable us to protect from that particular disease.
Several diseases, including cholera, tuberculosis, smallpox, and hepatitis B, etc. can be prevented by vaccination.
Children are vaccinated to protect from many diseases. WHO (World Health Organisation), which is an international organization, made the world almost free from small pox and polio like deadly diseases after introducing vaccination campaign worldwide.
Discovery of Vaccine for Small Pox
An English Scientist, Edward Jenner, discovered the vaccine for small pox in the year of 1798. Because of vaccine discovered by him, the life of millions of people was saved from small pox and small pox has been eradicated completely. Before the discovery of vaccine, small pox was an epidemic.
Increasing the Soil Fertility
Microorganisms also help to increase the fertility of soil. Some bacteria and blue green algae are able to fix nitrogen from the atmosphere to enrich soil with nitrogen and increase its fertility.
These microorganisms absorb nitrogen from atmosphere and made available in the soil in soluble form. Plants absorb this soluble nitrogen from soil and sythesise nutrition.
The process of making available of nitrogen in soluble form in the soil is called Nitrogen Fixation and microorganisms who are responsible for this are called Biological Nitrogen Fixers.
Cleaning the Environment
Some microorganisms convert dead and decaying organisms into simple form of substances. Later plants use these converted simple substances accordingly.
Microorganisms are natural decomposer. This is the cause that dead animals and plants are disappeared after sometimes due to decomposing by microorganisms. Environment becomes clean after vanishing out of dead animals and plant after decomposing by microorganisms. This process of decomposing of dead animals and plants eventually replenishes nutrients back to the ecosystem, thereby, allowing the plants to grow.
So, microorganisms help us in cleaning in environment and keep us healthy.
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