This is an overall but brief discussion about all Microorganisms. This is a readymade slideshow for projects.

1. Microorganisms
By:-Piyush Mohite

2. What are
Microorganisms?
¤A microorganism is a
microscopic organism that
comprises either a single cell,
or multicellular organisms.
¤The study of microorganisms is
called microbiology, a subject
that began with Anton van
Leeuwenhoek’s discovery of
microorganisms in 1675, using a
microscope of his own design.

3. Types of Microorganisms
Bacteria
Fungi
Protozoa
Algae
Virus

4. Viruses
Viruses are too small to be seen with the naked eye.
They can’t multiply on their own, so they have to
invade a ‘host’ cell and take over its machinery in
order to be able to make more virus particles.
Viruses consist of genetic materials (DNA or RNA)
surrounded by a protective coat of protein. They are
capable of latching onto cells and getting inside
them.
The cells of the mucous membrane, such as those
lining the respiratory passage that we breathe
through, are particularly open to virus attacks
because they are not covered by protective skin.

5. Fungi
Fungi are like plants that are not ‘green'; they do
not have the photosynthetic material chlorophyll.
They have no roots, stems or leaves but grow as
masses of protoplasm in dead and living organic
matter. There are about 1,00,000 different fungi.
Some like the yeasts are single cells but most
fungi grow as branching tubes of protoplasm
called hyphae. Fungi also contain chitin which is
also found in animal cells. A single organism is
called fungus.

6. Bacteria
Bacteria are organisms made up of just one cell.
They are capable of multiplying themselves, as
they have the power to divide. Their shapes may
vary, and doctors use these characters to
separate them into groups.
Bacteria are omnipresent. Most are harmless,
even useful.
But some cause diseases, either because they end
up in wrong place or simply because they are
‘designed’ to invade us.

7. Protozoa
Protozoa are small (but not simple) organisms.
They are single-celled heterotrophic eukaryotes,
which eat bacteria and other food sources.
There are about 30,000 protozoan species.
They are found only in moist or aquatic habitats.
Many protozoan species are symbionts, some
are parasites, and some are predators of soil
bacteria and algae.

8. Algae
Algae are a type of living thing that usually live
in really wet environments, like the oceans. They
are a little bit like plants.
They too, carry out photosynthesis, just like the
plants do!
The difference between algae and plants, is that
plants have a lot of more distinct parts, like
roots, stem and leaves.

9. Useful microorganisms
 Bacteria live on and in our bodies and keep us alive!

10. Helpful Fungus
 Mould is a type of fungus.
 A mould called penicillin is an antibiotic (medicine) we
take to kill bad bacteria.
 Yeast is another type
of fungus.
 We use yeast when
baking bread
(releases CO2) and
to make wine
(creates ethanol).

11. Helpful Bacteria
 Bacteria are used to make cheese and
yogurt!
 Different types of
bacteria cause
different tastes!

12. Harmful microorganisms
o Some microorganisms cause diseases in plants and
animals. Such disease causing microorganisms are called
pathogens.
o Some microorganisms grow in food substances and
produce toxic substances and makes the food poisonous.
Food poisoning causes illness and even death.
o Some microorganisms spoil materials like clothing, leather,
wood etc.

13. Disease causing microorganisms
in Humans
o Disease causing microorganisms enter our body through
air, water, food, contact or insects. These microorganisms
are called pathogens.
o Diseases which can spread from an infected person to a
healthy person are called communicable diseases.
o Eg :- cholera, common cold, chicken pox, tuberculosis etc.
o Some insects and animals act as carriers of disease
causing microbes.
o Eg :- House fly, Female anopheles mosquito (malaria),
Female aedes mosquito (dengue fever) etc.

14. Disease causing microorganisms
in plants
Microorganisms cause diseases in plants like rice, wheat,
potato, sugarcane, apple, orange etc. These diseases reduce
crop yield. They can be controlled by using chemicals which
kill the microbes.

15. Some common human diseases caused by
microorganisms
Human disease Causative Mode of
microorganism transmission
 Chicken pox Virus Air / Contact
 Polio Virus Air / Water
 Measles Virus Air
 Hepatitis – B Virus Water
 Tuberculosis Bacteria Air
 Typhoid Bacteria Water
 Cholera Bacteria Water / Food
 Malaria Protozoa Mosquito
Some common plant diseases caused by
microorganisms
Plant disease Causative Mode of
microorganism transmission
 Citrus canker Bacteria Air
 Rust of wheat Fungi Air / Seed
 Yellow mosaic of
Okra (Lady’s finger) Virus Water

16. Food preservationFood is spoilt by microorganisms. Spoilt food has bad smell and bad
taste and causes food poisoning. Food can be preserved by protecting
it from microorganisms. Food can be preserved by different methods.
They are :-
 Chemical method :- Food like pickles can be preserved by using
chemicals like salts and edible oils. Jams and squashes can be preserved
by using sodium benzoate, sodium metabisulphite. These chemicals are
called preservatives.
 By using common salt :- Food items like fish, meat, amla, raw mangoes,
tamarind etc. can be preserved by using common salt. It prevents the
growth of microbes.
 By using sugar :- Food items like jams, jellies, squashes etc. can be
preserved by using sugar solution. It prevents the growth of microbes.
 By using oil and vinegar :- Food items like pickles, vegetables, fish, meat
etc. are preserved by using oil and vinegar. It prevents the growth of
microbes.
 By heat and cold treatments :- Heating food items kills microbes. Similarly
storing food items at low temperatures prevents growth of microbes.

17.  Pasteurization :- The process of heating milk to about 70oC for 15 to 30 seconds
and then suddenly chilling it to prevent the growth of microbes is called
pasteurization. This process was discovered by Louis Pasteur.
 By storage and packing :- Many food items are stored in air tight containers to
protect them from microbes.

18. Nitrogen cycle
The nitrogen in the atmosphere is converted into nitrogen compounds
in the soil by nitrogen fixing bacteria and blue green algae. Lightning
also converted into nitrogen compounds in the soil. The nitrogen
compounds in the soil is used by plants for the synthesis of proteins
and other compounds. Animals feeding on plants get these proteins
and other compounds. When plants and animals die, bacteria and fungi
in the soil converts the nitrogenous waste into nitrogen compounds in
the soil which are again use by plants. Some other bacteria converts
some nitrogen compounds in the soil into nitrogen gas which goes back
into the atmosphere. Hence the nitrogen in the atmosphere almost
remains constant.

19. Nitrogen cycle ATMOSPHERIC
NITROGEN
LIGHTNING FIXES
NITROGEN
NITROGEN FIXING BACTERIA
AND BLUE GREEN ALGAE
FIX ATMOSPHERIC NITROGEN
COMPOUNDS OF
NITROGEN IN THE SOIL
UPTAKE BY
PLANTS
ANIMAL EATS
PLANTS
BACTERIA TURN
COMPOUNDS OF
NITROGEN INTO
GASEOUS NITROGEN
NITROGENOUS
WASTE FROM
EXCRETION
AND DEATH

20. Thank
You
Piyush Mohite