3. What are Microorganisms?
• The organisms which are too
small to be seen by our naked
eyes are called Microorganisms.
• The study of microorganisms is
called Microbiology.
• Antonie Van Lewenhoek was
the first scientist who observed
small moving organisms in a
drop of lake water under his
microscope. He named them
“animalcules”.
4. Where do Microorganisms live?
• Microorganisms are omni
present, i.e. Microorganisms are
found everywhere in the air,
water, soil and even inside the
living organisms.
• They can survive extreme
conditions like hot spring to
polar region.
• They can survive too acidic and
too alkaline environment.
• Under unfavorable condition of
temperature and water, they
form hard and tough covering
called cysts.
Spiral bacteria Rod shaped bacteria
Chlamydomonas Spirogyra
Algae
6. Classification of Microorganisms
1. Based on Characteristics :
a) Bacteria : Unicellular, Prokaryotic, occurs
in various sizes and shapes. Ex:
Lactobacillus
b) Fungi : saprophytic, can be unicellular or
multicellular. Ex: Penicillium, Aspergillus
c) Algae : photosynthetic micro-organisms.
Ex: Spirogyra
d) Protozoa : unicellular, prokaryotic. Ex:
Amoeba
e) Virus : neither living nor nonliving. Form
the boundary between the living and the
nonliving. Ex: Bactriophage, HIV
7. 2. Based on the number of cells:
a) Unicellular – most of the protozoans
b) Multicellular – most fungi and some algae
3. Based on the significance:
Micro-
organisms
Bacteria Fungi Protozoa Algae Virus
Useful Lactobacillus Yeast Tetrahymena
pyriformis
Red algae Lambda phage
Harmful Haemophilus
influenza
Rhizopus Plasmodium Gymnodinium Picorna
8. Uses of Microorganisms
Used in the
preparation of
curd, bread and
cake.
Used in
cleaning up of
environment.
Used in the
preparation of
medicines.
Used to
increase soil
fertility by
fixing nitrogen.
9. Useful Microorganisms
Lactobacillus – curdling of milk
Yeast – Making bread, cake, alcohol, wine etc.
Tetrahymena pyriformis - is the most commonly ciliated model used
for laboratory research. Tetrahymena pyriformis was the first protozoan
to be cultivated axenically, in the absence of any other organism. Mainly
this factor is responsible for its extensive use as a model cell system. Its
biology and biochemistry have been studied extensively and so has its
response to altered environmental conditions.
Red Algae - Red algae are used as the source of food for thousands of
years as they are high in vitamins, minerals, a rich source of calcium,
magnesium, and antioxidants. The high fibre content of red algae means
it is also useful in improving digestion.
Lambda phage - Lambda phage has been of major importance in the
study of specialized transduction. Specialized transduction is the process
by which a restricted set of bacterial genes are transferred to another
bacterium.
10. Uses of Microorganisms
1. Microbe’s role in curdling of milk – Microbes play a
vital role in preparing curd from milk. Curd contains a
bacterium, Lactobacillus. Lactobacillus is a friendly
bacterium. It treats and prevent diarrhea, help in
food breakdown and absorption of nutrients.
• Lactobacillus converts sugars in milk (Lactose) into
Lactic acid.
• Lactic acid imparts sour taste to curd.
• Increased acidity causes milk protein (Casein) to turn
into solid masses. This changes the texture of curd.
11. 2. Microbe’s role in bakery and
fermentation –
• Louis Pasteur discovered the
process of fermentation in 1857.
• Yeast respire under anaerobic
condition.
• Yeast is used in industrial
production of alcohol and wine.
• Yeast are also used in baking
industry for making bread, cakes,
pastries, buns.
• Yeast multiply rapidly in dough
and produce CO2 and the dough
rises.
12. 3. Microbe’s role in preparation of antibiotics – Antibiotics are
chemicals that are produced by certain micro-organisms especially
bacteria and fungi and are used to cure a variety of diseases.
• Streptomycin, tetracycline and erythromycin are some commonly
known antibiotics which are mage from fungi and bacteria.
• In 1929, Alexander Fleming was working on a culture of disease
causing bacteria when he found the spores of little green mould
in his culture plate. The mould separated was identified as
Penicillium notatum. He observed that the presence of mould
prevented the growth of bacteria and also killed many of these
bacteria. And this is how mould penicillin was prepared.
• Dr. Yellapreggada SubbaRao , born in west Godavari district of
Andra Pradesh state, India was well known for his discovery of
Aureomycin, a tetracycline that cure number of bacterial diseases
like Typhoid, Plague, Tuberculosis etc.
13. 4. Microbe’s role in preparation of Vaccines - Vaccines
are made from microbes that are dead or inactive so that
they are unable to cause disease. The antigen in the
vaccine is the same as the antigen on the surface of the
disease-causing microbe. The vaccine stimulates the
body to produce antibodies against the antigen in the
vaccine.
• Edward Jenner discovered the vaccine for small pox in
1798.
• Dr. Jonas Sack discovered polio vaccine in 1952 and Dr.
Albert Sabin discovered oral vaccine in 1957.
