microbial world part -i.doc

7/30/2019 MICROBIAL WORLD PART -I.doc

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MICROBIAL WORLD

THE STORY OF MICROORGANISMS

Part -I

Let us think over following questions.

Why do we add some drops of butter milk to lukewarm milk while

making curd?

Why does even cooked food get spoiled after some days?

Why do we get bad smell from our mouth after we wake up in the

morning?

In this chapter we will try to find out what may be involved in causing

such changes.

Years back several people wondered over such questions and tried to find

out answers of such questions.

One such example is about Anton van Leeuwenhoek.

Story of Microscope invention and discovery of microorganisms

Anton van Leeuwenhoek single lens powerful microscope

Microbiology as a science was born in 1674 when Anton vanLeeuwenhoek peered at a drop of lake water through a glass lens that he had

carefully ground. Anton van Leeuwenhoek was a fabric merchant.

Leeuwenhoek built a single lens powerful microscope, which can magnify the

object 300 times. His curiosity and skill of making powerful lenses were the

secrets of this invention of powerful microscope. His keen observation of

different things under his microscope helped him to discover smallest moving

organisms in 1678. He called them as animalcules, later which were named as

bacteria. Along with animalcules he observed many other microorganisms


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under his microscope which got their respective names later on. This helped

further discovery of other microorganisms.

Now let us see what are Microorganisms and where we can find them.

Microorganisms

We can see some organisms with our naked eyes, like plants and animals

around us. But some organisms are so small that we cannot see them with our

naked eyes. We can see them only with help of a microscope. They are called

as microorganisms. Some of the microorganisms are shown in Fig.2.1 to 2.5

Bacteri of different shapes Lactobacillus

Fig.2.1Bacteria as seen under Electron microscope

: Penicillium Bread mould Rhizopus Aspergillus

Fig.2.2 Fungi

Amoeba ( 500 Microns ) Paramecium ( 0.25m.m )


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Fig.2.3Protozoans

Ceratium

Chlamydomonas Spirogyra Spirulina

Oedogonium Vorticella Osillotoria

Fig.2.4 Algae

cylapse DaphniaScabies mite Eyelash mite


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Fig. 2.5 Micro Arthropods

Groups of microorganisms

Let us study some major groups of microorganisms. They are bacteria, fungi,

protozoa, algae and certain micro arthropods.

To study these major groups we will do some activities.

For this we will need a Microscope. You already know how to use it. You

could also refer to class VI Chapter 16 and class VIII Chapter --

Activity 1 : Collect some pond water / or water from any tank in your

surrounding. Ensure to take some of the greenish scrapings from side

of the tank. Take 1-2 drops of water (from the sample you have collected) ona slide and observe through Microscope. Draw rough sketches in your note

book of what you observed. Take the help of given figures on page --- for

observation and identification (you may also discuss with your friends). Take

the help of your teacher as well.

Help Box

Can you name the organisms you have observed through the microscope?

We will try to know more about the microscopic world by doing the following

activities.

Observing Fungi

Usually after the rainy season you may have seen some small umbrella like

growths over rotten materials of dumped wast between the grasses in a field or

edges of wet rotten wooden planks. Often you may have observed white patches

on the bark of trees. These are a few types of fungi. Now let us look at them

more closely by the following activity.

Photographs of

microbes in pond

water, ex:

Spirogyra,

paramecium,


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Activity 2: Take some rotten part of vegetable or black spoiled part of bread or

coconut with help of a needle on a slide. Put a drop of water, cover with a cover

slip and observe through microscope.

Draw rough sketches in your note book of what you observed. Take thehelp ofhelp boxfor the same.

Help Box

Observing Bacteria

We can see these in butter milk or curd or early morning scraping of tongue

(before washing the mouth). We can also find them in the soil, over bark of

trees, over our skin and many other places. But they are not visible to the naked

eye. Now let us look at them more closely by the following activity.

Activity 3:Take one or two drops of butter milk on a slide, spread it on the slide. Heat it

slightly on a lamp (3-4 seconds). Add a few drops of cristal violet on it. Leave

it for 30 to 60 seconds and wash the slide gently with water. Observe the slide

under the compound Microscope. Draw rough Sketches in your note book of

what you observed. Take the help of the given help boxfor observation.

Help Box

Picture of actual observation of lactobacillus

ex.Rhizopous


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Photographs of curd in bowl Lactobacillus bacterium

Observing Algae

We observe greenish pond water in our surroundings. This greenishness is

because of growth of Algae and other plants in water. We can see some of algae

with naked eye like chora, but most of the algae present in water is also

microscopic.They can be observed only through a microscope. Let us collect

pond water or water from the tanks with bit of greenish scrapings to do the

following activity.

Activity

Select a few strands (green string like bodies).or some part of the

scrapings that have small string like bodies. Take one or two drops of collected

greenish pond water (in a bottle) on a slide. Cover it with a cover slip and

observe through microscope. Draw rough sketches in your note book of what

you observed. Take the help ofhelp boxfor the same.

Do you know?

There are several Bacteria growing on our skin. Many of the diseasecausing ones live in some symbiotic relations with other bacteria. There are several

types of them in our body as well. We cannot do without the bacteria present inside

our intestine.

Bacteria are found everywhere and there are over thousand types of them

in soil, water etc. Recently two types of bacteria nearly a millimetre long were

discovered which can be seen with naked eye.

Do you know?

Micro Algae photosynthesis is important for life on earth. They produce

approximately half of the atmospheric oxygen needed by other orgonismsand use

green house gase carbon dioxide. The bio diversity of Micro Algae is enormous.

It has been estimated that about 2 lakhs to 8 lakhs species exist.


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Observing Protozoa

Some of other group of microorganisms are protozoans. Most of the

protozoans present in the water and soil. We can see them through microscopeonly. Let us do the following activity to observe them.

Do you Know?

To grow protozoans prepare dication of hay and take in a bowl and add some

collected pond water to it. After 3- 4 days take drop of water and observe under

compound microscope. You can also add some boiled bendi pieces to the hey

dication.

Activity

Take one or two drops of hay decation water on a slide and observe under the

microscope. Draw rough Sketches in your note book of what you observed.

Take the help of the given help boxfor observation.

Microorthropods

We can see some arthropods with our eyes such as Ants, Cockroaches,

Scorpions, etc. But some arthropods are microscopic which are known as micro

arthropods. Some micro arthropods are very important in soil which helps in

soil fertility by decomposing the biomass through disetion which converts the

bigger compounds in to smaller compounds.

Some micro arthropods cause diseases like scabies e.g.: scabies mites.

Observing soil microorganisms[

Do you know?

Soil is highly rich of microorganisms such a bacteria, fungi,

Actinomyceties, protozoans, microorthropods. The top of eight inch soil of one

acre may contain as much as five and half tons of fungi and bacteria. We can see

them trough microscope only, by growing them in different media. Let us do

following activity to observe some of soil microbes.


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Do you know?

Viruses are very interesting type of microorganisms. They behave like non

living things when they are outside of a living cell. But they behave like living

organisms by reproducing in host living cells like bacteria, plants or animals.

They can only be seen through very powerful electron microscope. Some Viruses

are shown in Fig-2.

HIV

Fig.2.5 Viruses

Diseases like polio, swine flu, conjunctivitis, smallpox, chickenpox and AIDS are

caused by viruses.


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Activity 4: Collect some soil from the field in a beaker or in a glass .Add

some water to it and stir it. Wait for some time to let the soil particles settle

down. Take a drop of water on a slide and observe under the Microscope. Draw

rough sketches in your note book of what you observed. Take the help ofhelp

boxfor observation.

Help Box

Photographs and ex. Of soil micro orgsanisms

microorthropod mites, worms, fungal, spores, fungal

hyae.

Do you know?

To grow soil microbes we must add 2-3boiled cucumber pieces to

the soil mixed water and keep it for there to four days. Observe on the cucumber

pieces. Take little part of Cucumber piece and observe under Microscope. Take

help of your teacher.

From the above activities you would be able to understand the diverseness of

the microorganisms. You can also appreciate the fact that this is another

amazing world of living organisms.

Let us try to find out where else we can find them.

Where are microorganisms present?

Microorganisms present everywhere around us. They present in air,

water, soil. They are also present inside and outside of animals including human

beings and on plants. They can survive in all types of environments ranging

from ice cold climate to hot springs, deserts to marshy lands. Some

microorganisms grow on other organisms (parasites) and some may exist

independently like algae

Diseases like typhoid, tuberculosis (T.B) and septicaemia (blood poisoning)

caused by bacteria. Some of the skin diseases are caused by fungi while others


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by microorhropods and bacteria. Diseases like Malaria, Amoebiasis are caused

by Protozoa (Protozoans)

DO YOU KNOW?

BACTERIAL STAINING

Bacterias are very small/tiny microorganisms. We must stain before seeing

BACTERIA UNDER MICROSCOPE. Smear bacteria on a slide and slightly heat

the slide. Then put drops of crystal violet on the slide, after 30 to 60 seconds

gently wash the slide. Dry the slide and now watch the slide under the

microscope in 25 X or 40 X.

KEY WORDS

Microorganism , Microscope, Bacteria, Fungi, Protozoa, Algae,

Virus, discovery, invention

What we have learnt?

Microorganisms are very minute. We cannot see them with our naked eye.

We can see microorganisms with help of Microscope.

Microbes present everywhere in our surroundings.

Bacteria, Fungi, Protozoa, and Algae are major groups of microorganisms.

Viruses are special type of microorganisms, which stands between living and

non living organisms. They can reproduce only in host living cell.

Improve your learning

1. Observe some useful and harmful microorganisms on preparedpermanent slides with help of Microscope, and note them down.


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2. Visit any Microbiology department of Degree, PG College or University

nearby you with help of your teacher or parents .Know some techniques

to culture some Microorganisms from air, water, soil and from rotten

vegetables or fruits.

3. Prepare one Bacterial or Fungal medium with help of your teacher and

grow some bacteria or fungi in them and observe the appearance and colour of

these.

4. what type of microorganisams we can observe in pond

water?

5. How can we observe Lactobacillus bacterium?

microbial world part -i.doc

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