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MICROORGANISMS:
FRIENDS AND FOE
Presented By:-
RUCHI
CRCOE HISAR

MICROORGANISMS
o Microorganisms are very small organisms
which cannot be seen with the unaided eye.
They can be seen only with a magnifying glass
or microscope.

? Microorganisms may be unicellular or
multicellular.
? Microorganisms may be single-celled like
bacteria, some algae and protozoa, or
multicellular, such as many algae and fungi.
? Microorganisms may exist alone or in colonies.

WHERE DO MICROORGANISMS
LIVE..??
? Microorganisms live in all types of
environment, ranging from ice cold climate to
hot springs; and deserts to marshy lands.
? They are also found inside the bodies of
animals including humans.
? Some microorganisms grow on other
organisms while others exist freely.

TYPES OF MICROORGANISMS
? There are four main types of
microorganisms. They are:
? Bacteria (Examples- Streptococcus,
Staphylococcus etc.);
? Fungi (Examples- Penicillium, Yeast
etc.);
? Algae (Examples- Nostoc, Volvox etc.);
? Protozoa (Examples- Amoeba,
Paramecium etc.)
? Viruses are also considered as
microorganisms.
Eg. of virus- Coronavirus, Hepatitis etc.
Penicillium

MICROORGANISMS AND US
? Microorganisms play an important role in our lives.
Some of them are beneficial in many ways whereas
some others are harmful and cause diseases.

FRIENDLY MICROORGANISMS
? Microorganisms are used for
various purposes. Some of
them are:
? Making Curd:
The bacterium called Lactobacillus
reproduces in milk and helps to
convert milk into curd.
? Making Bread:
The fungus called yeast reproduces
in flour dough and produces carbon
dioxide during respiration which
makes the dough soft.

? Making Alcohol:
The fungus called yeast reproduces in sugar
solution and convert it into alcohol. This
process is called fermentation.
? Making medicines:
Some bacteria and fungi are used to
make medicines which kills or stops the
growth of disease causing
microorganisms. Such medicines are
called antibiotics. Eg:- Streptomycin,
Penicillin, tetracyline, erythromycin etc.

?Vaccines:
Vaccines are dead or weakened microbes introduced into
the body to produce antibodies. These antibodies protect
the body from disease causing microbes. Diseases like
Polio, cholera, typhoid, small pox, hepatitis etc. can be
prevented by taking medicines.

? Increasing Soil
Fertility:
Some bacteria like
(Rhizobia, Nostoc) are able
to fix nitrogen from the
atmosphere to enrich soil
with nitrogen and increase
its fertility. These microbes
are commonly called
Biological nitrogen fixers.
? Cleaning the
environment:
Microorganisms can be used
to degrade the harmful and
small substances and thereby
cleanup the environment.
Example-Pseudomonas putida
Pseudomonas putida

?Microbes Help in Sewage Treatment:
Sewage treatment is a process in which the
pollutants are removed. Microbes are used to
degrade organic matter while producing water and
byproducts consistent with the type of bacteria
grown.

?Microbes in Human Gut:
Lactobacillus is a type of bacteria found in
human intestines. Its name gives an
indication of what it produces �� lactic
acid. It does this by producing an enzyme
called lactase. Lactase breaks down
lactose, a sugar found in milk, into lactic
acid. Lactobacillus can help us break
down food, absorb nutrients, and fight off
"unfriendly" organisms that might cause
diseases such as diarrhea.

HARMFUL MICROORGANISMS
? Microorganisms are harmful in many ways. Some of their
harmful activities are:
? Disease causing Microorganisms
in Humans:
a) Disease causing microorganisms enter
our body through air, water, food,
contact or insects. These
microorganisms are called pathogens.
b) Disease which can spread from an
infected person to a healthy person are
called communicable diseases. Eg-
Cholera, Tuberculosis etc.
c) Some insects can also act as carrier of
disease causing microbes.
Example- House fly, Female anopheles
mosquito (Malaria).

? Disease causing Microorganisms in plants:
Several microorganisms cause diseases in plants like wheat,
rice, potato, sugarcane, orange, apple and others. The
diseases reduces the yield of crop.
Plant Diseases Microorganism Mode of Transmission
Citrus Canker Bacteria Air
Rust of Wheat Fungi Air, Seeds
Yellow vein Virus Insect
Mosaic of bhindi
(Okra)
Table showing some plant disease causing microorganisms.

? Disease causing Microorganisms in Animals:
Several microorganisms not only cause diseases in humans and
plants, but also in other animals.
? Food and mouth disease of cattle is caused by a virus.
? Anthrax is a dangerous human and cattle disease caused by a
bacterium.

?FOOD POISONING:
? It can be due to the consumption of food spoilt by some
microorganisms.
? Microorganisms that grow on our food sometimes produce
toxic substances, these make the food poisonous causing
serious illness and even death.
? So it is very important that we preserve food to prevent it from
being spoilt.

BIOLOGICAL WARFARE:
? Biological weapons include
living organisms and
biologically produced toxins to
injure people, animals and
destroy crops. These include
harmful microbes such as
Bacteria, Viruses and spores.
Toxins are produced by these
microbes. This causes mass
destruction of populations.

?BIODETERIORATION OF MONUMENTS:
Cultural heritage monuments may be discolored
and degraded by growth and activity of
living organisms. Microorganisms form biofilms
on surfaces of stone, with resulting aesthetic and
structural damage.

TOOTH DECAY
?Tooth decay, also known as dental caries or
cavities, is a breakdown of teeth due to acids
made by bacteria.
?Streptococcus is the main cause of dental
decay.

ALGAL BLOOM
?Increase growth of
algae in water
systems leads to
decrease in oxygen
in water bodies
and this can be
threat to aquatic
life.

CONCLUSION
? Microorganisms are very small organisms which
cannot be seen with the unaided eye. They can be
seen only with a magnifying glass or microscope.
? Some of them are beneficial in many ways whereas
some others are harmful and also causes diseases.

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Microorganisms

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Editor's Notes