Biology

project file
Class-12 session-2022-
2023
 Submitted by
mentor’s name
Aman mourya shruti
ma’am

ACKNOWLWDGEME
NT
I TAKE THIS OPPORTUNITY TO
SINCERELY EXORESS MY
GRATITUDE TO ALL FOR
HELPING ME COMPLETE THIS
PRACTICLE FILE.MY SINCERE
THANKS TO MRS.SHRUTI
SHARMA, MY BIOLOGY
TEACHER FOR HER CONSTANT
SUPPORT AND
ENCOURAGEMENT WITHOUT
WHOSE HELP AND GUIDANCE I
WOULD NOT HAVE BEEN ABLE
TO COMPLETE THIS FILE.

ALSO, I WOULD LIKE TO

THANK ALL THOSE WHO
PROVIDED REQURED
MATERIAL FOR COMPLETING
THE PROJECT.

CERTIFICATE
THIS IS TO CERTIFE THAT THIS PROJECT HAS
BEEN BY MADE BY AMAN MOURYA OF CLASS
12th ON THE TOPIC

“MICROBE IN HUMAN
WELFARE”
Under the guidance of our biology
teacher shruti sharma and have been
complete it.
Aman Mourya

INDEX
SERIAL NO. TOPIC
1 MICROBES IN HOUSEHOLD PRODUCTS

2 MICROBES IN INDUSTRIAL PRODUCTS

3 MICROBES IN SEWAGE TREATMENT

4 MICROBES IN PRODUCTION OF BIOGAS

5 MICROBES AS BIOCONTROL AGENTS

6 MICROBES AS BIOFERTILISERS

7 BIBLIOGRAPHY

BIBLIOGRAPHY
1.websites:
 WWW.google.co.in
  www.ncert.nic.in
 www.wikipedia.org
 www.yahoo.com
2.BOOKS:
 Comprehensive practical
manual
 Nirmal new course chemistry
 NCERTA class XII
 8.1 MICROBES IN HOUSEHOLD

PRODUCTS

 A common example is the production of curd from

milk. Micro-organisms such as Lactobacillus and
others commonly called lactic acid bacteria (LAB)
grow in milk and convert it to curd. During growth,
the LAB produce acids that coagulate and partially
digest the milk proteins.
 Curd also improves its nutritional quality by
increasing vitamin B12.
 the LAB play very beneficial role in checking disease
causing microbes
 The dough, which is used for making foods such as
dosa and idli is also fermented by bacteria.
 The puffed-up appearance of dough is due to the
production of CO2 gas.
 The dough, which is used for making bread, is
fermented using baker’s yeast(Saccharomyces
cerevisiae).
 Different varieties of cheese are known by their
characteristic texture, flavour and taste, the
specificity coming from the microbes used.
 The large holes in ‘Swiss cheese’ are due to
production of a large amount of CO2 by a bacterium
named Propionibacterium sharmanii.
 The ‘Roquefort cheese’ are ripened by growing a
specific type of fungi on them, which gives them a
particular flavour.

8.2 MICROBES IN INDUSTRIAL

PRODUCTS

 microbes are used to synthesise a number of products

valuable to human beings.
 Production on an industrial scale, requires growing
microbes in very large vessels called fermenters.
 Microbes especially yeasts have been used from time
immemorial for the production of beverages like wine,
beer, whisky, brandy or rum.
 Depending on the type of the raw material used for
fermentation and the type of processing (with or without
distillation) different types of alcoholic drinks are
obtained. Wine and beer are produced without
distillation whereas whisky, brandy and rum are
produced by distillation of the fermented broth.
 Antibiotics produced by microbes are regarded as one
of the most significant discoveries of the twentieth
century.
 Antibiotics are chemical substances, which are
produced by some microbes and can kill or retard the
growth of other (disease-causing) microbes.
 You are familiar with the commonly used antibiotic
Penicillin.
 Alexander Fleming while working on Staphylococci
bacteria, once observed a mould growing in one of his
unwashed culture plates around which Staphylococci
could not grow. He found out that it was due to a
chemical produced by the mould and he named it
Penicillin after the mould Penicillium notatum.
 its full potential as an effective antibiotic was
established much later by Ernest Chain and Howard
Florey.
 This antibiotic was extensively used to treat American
soldiers wounded in World War II.
 Fleming, Chain and Florey were awarded the Nobel
Prize in 1945, for this discovery.
 Antibiotics have greatly improved our capacity to
treat deadly diseases such as plague, whooping cough
(kali khansi ), diphtheria (gal ghotu) and leprosy (kusht
rog), which used to kill millions all over the globe.
 Microbes are also used for commercial and industrial
production of certain chemicals like organic acids,
alcohols and enzymes. Examples of acid producers are
Aspergillus niger (a fungus) of citric acid, Acetobacter
aceti (a bacterium) of acetic acid; Clostridium butylicum
(a bacterium) of butyric acid and Lactobacillus (a
bacterium) of lactic acid.
 Yeast (Saccharomyces cerevisiae) is used for
commercial production of ethanol.
 Lipases are used in detergent formulations and are
helpful in removing oily stains from the laundry.
 Streptokinase produced by the bacterium
Streptococcus and modified by genetic engineering is
used as a ‘clot buster’ for removing clots from the blood
vessels of patients who have undergone myocardial
infarction leading to heart attack.
 cyclosporin A, that is used as an immunosuppressive
agent in organ-transplant patients, is produced by the
fungus Trichoderma polysporum.
 Statins produced by the yeast Monascus purpureus
have been commercialised as blood-cholesterol lowering
agents. It acts by competitively inhibiting the enzyme
responsible for synthesis of cholesterol.
8.3 MICROBES IN SEWAGE
TREATEMENT

 Before disposal, hence, sewage is treated in

sewage treatment plants (STPs) to make it less
polluting.
 Treatment of waste water is done by the
heterotrophic microbes naturally present in the
sewage. This treatment is carried out in two
stages.
1. Primary treatments: These treatment steps
basically involve physical removal of particles –
large and small – from the sewage through
filtration and sedimentation. These are removed
in stages; initially, floating debris is removed by
sequential filtration. Then the grit (soil and small
pebbles) are removed by sedimentation. All
solids that settle form the primary sludge, and
the supernatant forms the effluent. The effluent
from the primary settling tank is taken for
secondary treatment.
2. Secondary treatment or Biological treatment:
The primary effluent is passed into large aeration
tanks where it is constantly agitated
mechanically and air is pumped into it. This
allows vigorous growth of useful aerobic
microbes into flocs. This significantly reduces the
BOD (biochemical oxygen demand) of the
effluent. The sewage water is treated till the BOD
is reduced. BOD is a measure of the organic
matter present in the water. The greater the BOD
of waste water, more is its polluting potential.
waste water is reduced significantly, the effluent
is then passed into a settling tank where the
bacterial ‘flocs’ are allowed to sediment. This
sediment is called activated sludge. The
remaining major part of the sludge is pumped
into large tanks called anaerobic sludge
digesters. During this digestion, bacteria produce
a mixture of gases such as methane, hydrogen
sulphide and carbon dioxide. These gases form
biogas and can be used as source of energy as it
is inflammable. The Ministry of Environment and
Forests has initiated Ganga Action Plan and
Yamuna Action Plan to save these major rivers of
our country from pollution. Under these plans, it
is proposed to build a large number of sewage
treatment plants so that only treated sewage
may be discharged in the rivers.
8.4 MICROBES IN
PRODUCTION OF BIOGAS

 Biogas is a mixture of gases (containing

predominantly methane) produced by the
microbial activity and which may be used as
fuel.
 In production of beverages, the main gas
produced was CO2. certain bacteria, which
grow anaerobically on cellulosic material,
produce large amount of methane along
with CO2 and H2 These bacteria are
collectively called methanogens, and one
such common bacterium is
Methanobacterium.
 These bacteria are commonly found in the
anaerobic sludge during sewage treatment.
These bacteria are also present in the rumen (a
part of stomach) of cattle.
 In rumen, these bacteria help in the
breakdown of cellulose and play an important
role in the nutrition of cattle.
 the excreta (dung) of cattle, commonly
called gobar, is rich in these bacteria. Dung can
be used for generation of biogas, commonly
called gobar gas.
 The biogas plant consists of a concrete tank
(10-15 feet deep) in which bio-wastes are
collected and a slurry of dung is fed. A floating
cover is placed over the slurry, which keeps on
rising as the gas is produced in the tank due to
the microbial activity.
 The technology of biogas production was
developed in India mainly due to the efforts of
Indian Agricultural Research Institute (IARI)
and Khadi and Village Industries Commission
(KVIC).
8.5 MICROBES AS
BIOCONTROL AGENTS

 Biocontrol refers to the use of biological

methods for controlling plant diseases and
pests. These chemicals are toxic and
extremely harmful, to human beings and
animals alike, and have been polluting our
environment (soil, ground water), fruits,
vegetables and crop plants. Our soil is also
polluted through our use of weedicides to
remove weeds.
1. Biological control of pests and
diseases: In agriculture, there is a
method of controlling pests that relies on
natural predation rather than introduced
chemicals. A key belief of the organic farmer
is that biodiversity furthers health.
 the use of biocontrol measures will greatly
reduce our dependence on toxic chemicals
and pesticides.
 The very familiar beetle with red and black
markings – the Ladybird, and Dragonflies are
useful to get rid of aphids and mosquitoes,
 respectively. An example of microbial
biocontrol agents that can be introduced in
order to control butterfly caterpillars is the
bacteria Bacillus thuringiensis (often written
as Bt ).
 A biological control being developed for use
in the treatment of plant disease is the
fungus Trichoderma. Trichoderma species
are free-living fungi that are very common in
the root ecosystems. They are effective
biocontrol agents of several plant pathogens.
 Baculoviruses are pathogens that attack
insects and other arthropods. The majority of
baculoviruses used as biological control
agents are in the genus
Nucleopolyhedrovirus. These viruses are
excellent candidates for species-specific,
narrow spectrum insecticidal applications.
8.6 MICROBES AS
BIOFERTILISERS

 The Problems associated with the overuse of

chemical fertilisers and there is a large
pressure to switch to organic farming – the
use of biofertilisers.
 Biofertilisers are organisms that enrich the
nutrient quality of the soil. The main sources
of biofertilisers are bacteria, fungi and
cyanobacteria.
 Fungi are also known to form symbiotic
associations with plants (mycorrhiza). Many
members of the genus Glomus form
mycorrhiza.
 The fungal symbiont in these associations
absorbs phosphorus from soil and passes it
to the plant. Plants having such associations
show other benefits also, such as resistance
to root-borne pathogens, tolerance to
 salinity and drought, and an overall increase
in plant growth and development.
 Cyanobacteria are autotrophic microbes
widely distributed in aquatic and terrestrial
environments many of which can fix
atmospheric nitrogen, e.g. Anabaena,
Nostoc, Oscillatoria, etc
 In paddy fields, cyanobacteria serve as an
important biofertiliser. Blue green algae also
add organic matterserve as an important
biofertiliser. Blue green algae also add
organic matter to the soil and increase its
fertility.
 Currently, in our country, a number of
biofertilisers are available commercially in
the market and farmers use these regularly
in their fields to replenish soil nutrients and
to reduce dependence on chemical
fertilisers.

MADE BY: AMAN

MOURYA
CLASS: 12TH