is a realm of life made up of micro organisms, the branch of biological
sciences concerned with the study of microbes’ known as microbiology.
are unicellular, too small to be seen with the naked eye. Among all forms of
life on the earth these are stronger but their occurrence is undervalued
because of small size (0.2-2microns)
belongs to plant and animal kingdom.
These were first
observed by A.V.Leewenhoek.
Based on their
structures they are different kinds namely
ü Bacteria: Lactobacillus, Rhizobium.
ü Viruses: Mumps, Measles.
ü Protozoans: E.hystolitica, P.vivax.
ü Mycoplasms: C.trachomatis, T.pallidum
ü Algae: Nostoc, Volvox.
ü Fungi: Yeasts, Moulds.
Majority of micro organisms are harmful to living organisms and some of
them are highly beneficial. By the decomposition of dead bodies of plants and
animals they will return back to the
environment supplying nutrients to
the other plants and animals for their growth.
Now-a-days varieties of micro organisms are using to produce the substances
on large scale known as microbiology which
is developed into microbial biotechnology
or industrial microbiology.
Micro organism are very useful in the preparation of food, production of antibiotics,
organic acids, steroids, enzymes, bio fertilizers etc.
Products obtained by Micro organisms.
The cheese which is prepared without using the water known as ripening.
The coagulation of milk protein ‘casein’
results the semi solid substance known as cheese
is formed by the activity of Streptococcus
liquifaciens bacteria and moulds like Pencillium
and Aspergillus. Depending on
the type of milk, micro organisms, temperature and time they are about 300 varieties of cheese. Of that
ü Cottage cheese: It is a soft, lumpy
white cheese made from the curds of slightly soured milk. Examples: Ricotta, Mascarpone.
ü Cream cheese: It is soft rich cheese
made from unskimmed milk.
ü Hard cheese: It is a type of cheese
produced by repeatedly vigorous stirring and draining a mixture of curd and
Examples; Swiss, Cheddar etc.
ü Soft cheese: It is a type of cheese
which has not been pressed and has edible white blooms rind produced by
spraying the culture of Pencillium on the surface.
The fermented product obtained from the boiled milk known as curd,
fermentation is done by lactic acid bacteria
which help for the conversion of curd from milk by bringing milk proteins and fat globules together.
solid material of the curd: Butter.
liquid material of the curd: Butter
In the preparation of bread Sacchoromyces
cerevisiae ferment the
sugars of dough to produce carbon dioxide and alcohol. The gas helps in the
production of bread with porous, spongy structure and also in flavoring
the help of Sacchoromyces faecalis
and Leuconostoc mesenteroids, idly
and dosa are produced by overnight fermentation.
are the accessory growth substances required by the organisms in low
concentration and are synthesized by bacteria, yeast cells and fungi during the
Examples: Riboflavin: Ashby a gossyypii,
Phylloquine: Propionic bacterium.
of micro organisms are present in the stomach. Lower part of small and large
intestine of animals and human beings.
metabolic production of lactic acid
bacteria inhibit the growth of bacteria and releases phylloquine vitamin into the intestine then supplies to the body
hence normal bacterial flora should be maintains in the human intestine.
Examples: E.coli, Methanogenic bacteria.