Microbes
Microbes In Household Products
Microbes In Industrial Products
Microbes In Sewage Treatment
Microbes In Production Of Biogas
Microbes As
Biocontrol
Agents
Microbes As
Biofertilisers
1. Microbes are microscopic organisms (invisible to
naked eye)
2. They are present everywhere on earth
-
in soil, water,
air, in our bodies, plants and even at the most extreme
locations such as hot water geysers and poles.
3. Microbes are diverse, they can be
-
protozoa,
bacteria, fungi, viruses,
viroids
,
prions
etc.
4. Microbes are thought to be the main disease causing
agents, but they can be helpful to human beings in
many ways. We will see how in
subsequent
slides.
Escherichia coli
Lactobacillus
Azatobacter
Methanobactarium
1.
Production of curd from milk
a. Microbes such as Lactobacillus and a group called Lactic
Acid Bacteria(LAB) convert milk to curd by producing acids
which partially digest and coagulate milk
proteins.
b. A small amount of curd (starter or
inoculum
) which is
added to milk contains millions of bacteria which multiply
under suitable conditions and thus converting it to curd.
c. This process increases the nutritional value of milk by
increasing vitamin B12 , it also checks disease causing
organisms in our stomach.
2
.
Fermentation
a
.
The
fermentation
of
dough
is
due
to
bacteria
and
its
puffed
appearance
is
due
to
the
production
of
CO
2
during
fermentation
.
b
.
Toddy,
an
alcoholic
drink
is
made
from
Fermentation
of
palm
sap
.
c
.
A
yeast,
Saccharomyces
cerevisiae
(baker's
yeast)
is
used
for
fermenting
bread
dough
.
d
.
Cheese
is
also
a
product
of
fermentation
and/or
ripening,
and
different
varieties
of
cheese
are
due
to
different
microbes
used
for
fermenting
.
e
.
The
holes
in
cheese
are
due
to
large
CO
2
production
by
the
bacteria
.
Saccharomyces
cerevisiae
as seen under DIC (Differential
Interference
Contrast)
microscope.
The large holes in
Swiss
cheese
are due to huge amount of CO
2
released during fermentation by
P
ropionibacterium
shermanii
1. Beverages
2. Antibiotics
3. Organic acids
4. Enzymes
5.
Bio
-
active
molecules
1.
Beverages
a. When juices and malted cereals are fermented they get
converted to ethanol.
b. Brewer's yeast (
Saccharomyces
cerevisiae
) is commonly
used for fermentation.
c. Drinks with versatile
colour
and
flavour
are produced
depending upon the raw material and nature of processing
used
d. Classification of beverages
(
i
) Whisky, Rum and Brandy are distilled beverages.
(ii) Wine and beer are not distilled.
2
.
Antibiotics
a
.
The
term
means
'against
life'
with
reference
to
disease
causing
organisms
.
b
.
The
first
antibiotic
penicillin
was
discovered
by
Alexander
Fleming
.
c
.
Penicillin
is
obtained
from
a
fungus
Penicillium
notatum
.
d
.
These
are
used
in
treatment
of
a
number
of
diseases
such
as,
diptheria
,
leprosy,
whooping
cough,
plague
etc
.
3. Organic acids
a. Various organic acids are produced with the help of
microbes. The below lists the organic acids and name of
the microbe employed in producing it
-
Organic Acids
Microbe
1.
Citric Acid
2.
Acetic Acid
3.
Butyric acid
4.
Lactic
Acid
5.
Ethanol
1.
Aspergillus
niger
(fungus)
2.
Acetobacter
aceti
(bacterium)
3.
Clostridium
butylicum
(bacterium)
4.
Lactobacillus
(bacterium)
5.
Saccharomyces
cerevisie
(yeast)
4
.
Enzymes
produced
with
the
help
of
microbes
are
-
i
.
Lipases
(lipid
dissolving,
produced
by
Candida
lipolytica
)
ii
.
Proteases
iii
.
Pectinase
a
.
Lipases
are
added
in
detergents
for
removing
oily
stains
b
.
Pectinases
and
proteases
are
used
to
clear
fruit
juices
during
bottling
.
c
.
Streptokinase
is
produced
by
Streptococcus
.
It
is
modified
by
genetic
engineering
and
used
as
'clot
buster‘
for
dissolving
blood
clots
of
patients
after
myocardial
infarction
.
5. Bioactive molecules
a.
Cyclosporin
A
i
. A fungus
Trichoderma
Polysporum
produces it.
ii. It has
immuno
suppresive
properties so it is used as an
immuno
-
supressive
agent during organ transplantation.
b.
Statins
i
. These are the products of fermentation activity of yeast,
Monascus
purpureus
.
ii. It inhibits cholesterol synthesis, so used for
lowering
blood
cholesterol level.
Beer, a
product of
fermentation
Antibiotics
Acetic
acid, the
main
component
of
Vineger
Cholesterol lowering
tablets(statins)
Need for sewage treatment
-
1. The municipal waste water(sewage) contains large amount
of organic waste and microbes.
2. This can invite diseases and epidemic when this water
meets community water bodies like lake pond and rivers.
3. To check this the sewage is made less polluting by passing it
through sewage treatment plants(STPs)
This involves two steps
-
i
. Primary Treatment
ii. Secondary Treatment
1. Primary treatment
a. It is a physical process, it uses
sedimentation and
filtration
to filter small and large particles.
b. First the sewage is passed through mesh screens of
small pore sizes to remove floating objects like
polythene.
c. The grit is removed by
sedimentation
by passing
sewage into grit chamber.
d. Then it is kept in settling tanks, where the suspended
materials settle down to form the primary sludge.
e. The remaining fluid is taken for secondary treatment.
2. Secondary treatment
a. It is a biological process by heterotrophic bacteria present in the sewage.
b. The primary effluent is aerated in aeration tanks.
c. This causes rapid growth of aerobic bacteria, which then as '
flocs
'
consume the organic matter to
reduce the Biochemical Oxygen
Demand
(BOD).
d. After this the effluent is passed to settling tanks where these '
flocs
' get
sedimented
. (Activated Sludge).
e. A part of this sludge is pumped back to aeration tanks for further use.
f. This sludge is pumped to anaerobic sludge digesters, where anaerobic
bacteria form gases like methane CO
2
and H
2
S.
g. After this the effluent is released into water bodies like streams and rivers.
Microorganisms In Sewage Treatment
1.
Biogas
a. Biogas consists of methane(60%) and CO2(40%)
b. Produced by
Methanobacterium
by acting on
cellulosic compounds, these are found in rumen of
cattle and anaerobic sludge of sewage.
c. Cattle dung contains both cellulosic as well as
methanogens
so it's used for biogas production.
d. It is a popular method for meeting energy
requirements of rural households, and also helps in
reducing precious firewood.
2.
The steps involved in the production of biogas
-
a. The biogas plant consists of a 10
-
15 feet deep
concrete tank in which the slurry of dung is fed.
b. A floating cover is kept over the slurry which keeps on
rising as the gas is produced in the tank by microbial
activity.
c. An outlet connected to a pipe is present in the
biogas plant for the removal of biogas and supplying it
to required places.
d. The spent slurry is removed through another outlet
which can be used as a
fertiliser
.
A typical biogas plant.
A biogas plant in Tamil Nadu.
1.
Biological control
is defined as the reduction of pest
populations
by natural enemies and typically involves
an active human role.
2. For Example
-
a. The spores of
Bacillus
thuringiensis
(Bt) are toxic to
certain larvae, but not harmful for others.
b. The fungus
trichoderma
is being used for fighting
plant diseases.
c.
Baculoviruses
are the pathogens used for attacking
harmful insects and arthropods, they belong to genus
Nucleopolyhedrovirus
.
1. The use of
biofertilsers
instead of chemical ones has been
known to keep the soils fertility intact for longer durations. They
are organisms like bacteria, fungi and
cyanobacteria
, that
enrich the soil.
2. a. Bacteria
-
Rhizobium
,
Azospirilium
,
Azatobacter
fix
atmospheric nitrogen and enrich nitrogen content of soil.
b. Fungi
-
They form symbiotic relation with roots of plants
eg
.
mycorrhiza
. It absorbs phosphorous and passes it to plant, also
it shows resistance to pathogens and salinity.
c.
Cyanobacteria
-
They are autotrophic microbes which can
fix atmospheric nitrogen, for
eg
.
Anabaena,
Nostoc
,
Oscillatoria
. They are important
biofertilisers
in paddy
fileds
.
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