Based on Class 12 NCERT Biology Chapter: Microbes in Human Welfare

2. MICROBES
IN HUMAN
WELFARE
C H A P T E R 1 0

3. D O Y O U R E M E M B E R W H I C H
K I N G D O M S A M O N G T H E L I V I N G
O R G A N I S M S C O N TA I N M I C R O -
O R G A N I S M S ?
W H I C H A R E T H E O N E S T H AT A R E
O N LY M I C R O S C O P I C ?

4. MICROBES
• Microbes are diverse-protozoa, bacteria, fungi and
microscopic plants viruses, viroid and also prions
that are proteinaceous infectious agents.

6. MICROBES :OCCURRENCE
Microbes are present EVERYWHERE.
OMNIPRESENT!
• In soil, water, air.
• Inside our bodies and that of other animals and
plants. (e.g. Human microbiome)
• In extreme environments: Extremophiles
Thermophiles: e.g. Thermus aquaticus
Psychrophiles
Acidophiles, alkalophiles
Barophiles
Halophiles

7. Human Microbiome

8. MICROBES UNDER MICROSCOPE
E. coli
E. coli
Cyanobacteria
Streptococcus
Yeast
Aspergillus niger

9. Bacteriophage
Virus of the Corona family
Tobacco mosaic virus

10. MICROBES: GROWING MICROBES IN LAB
• Bacteria and fungi can be grown on nutritive
media to form colonies, which can be seen by
necked eyes and very useful in study of
microorganisms.
Colonies of E. coli
(bacteria)
Colonies of Candida albicans
(fungi)

11. MICROBES
• Microbes cause many diseases in human beings, plants
and animals.
• Several microorganisms are useful to man in diverse
ways.

12. MICROBES IN HUMAN
WELFARE
MICROBES IN HOUSEHOLD PRODUCTS
MICROBES IN INDUSTRIAL PRODUCTS
MICROBES IN SEWAGE TREATMENT
MICROBES IN PRODUCTION OF BIOGAS
MICROBES AS BIO CONTROL AGENTS
MICROBES AS BIOFERTILIZERS

14. FERMENTATION

15. MICROBES IN HOUSEHOLD
PRODUCTS
Name of Microbe Type Use
Lactobacillus and
LAB
Bacteria Curd making
b Yeast
(Saccharomyces
cervisiae)
Fungus Fermentation
Used in Dough and
traditional drinks
c Propionibacterium
sharmanii
Bacterium Cheese making
(Swiss cheese)

16. A. CURD: LACTIC ACID BACTERIA
• Lactobacillus and other commonly called lactic acid
bacteria (LAB) grow in milk and convert it to curd.
• They convert lactose sugar into Lactic acid.
• The LAB produces acids that coagulate and
partially digest the milk proteins.
• It also improves its nutritional quality by increasing
vitamin B12.
• In our stomach too, the LAB play very beneficial
role in checking disease-causing microbes.

17. B. YEAST (SACCHAROMYCES
CERVISIAE)
• The dough used for making foods such as dosa
and idli and bread is fermented by bacteria.
• The dough is fermented using baker’s yeast
(Saccharomyces cervisiae).
• The puffed-up appearance of dough is due to the
production of CO2 gas.
• Also used in making traditional foods and drinks
e.g. Toddy (traditional drink of southern India)

18. PROPIONIBACTERIUM
SHARMANII
• Cheese: Different cheese differ in
texture because of the microbe used
during fermentation.
• 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’ is ripened by
growing a specific fungus (Penicillium
roquefortii) on them for a particular
flavour.

19. MICROBES IN INDUSTRIAL
PRODUCTS

20. MICROBES IN INDUSTRIAL
PRODUCTS
• Fermentative activity of many microbes is used in industries for
production of antibiotics, baverages etc.
• Production on large scale requires growing microbes in very large
vessels called fermenters.
• Microbes are used for the industrial production of:
1. Fermented Beverages
2. Antibiotics
3. Chemical, Organic acids , Enzymes and other
Bioactive Molecules

22. 1. FERMENTED BEVERAGES
• Saccharomyces cerevisiae commonly called brewer’s
yeast, is used for fermenting malted cereals and fruit
juices, to produce beverages like wine, bear, whisky and
rum.
• Wine and bear are produced without distillation
whereas whisky, brandy and rum are produced by
distillation of the fermented broth.

23. Alcoholic beverages
• Beer contains 3 to 5
percent of alcohol.
• Wine contains 9 to 14
percent alcohol.
• Wine coolers are made of
wine mixed with
carbonated water and
flavourings. Wine coolers
have about 4 to 6 percent
alcohol.
• Distilled spirits such as
whiskey, gin, scotch and
vodka usually contain 35
to 50 percent alcohol.
Nutrient
source
Beverage
Barley malt Beer
Rye malt Gin
Rice Sake
Potato Vodka
Cereals Whiskey
Juices Wine, brandy

24. 2. ANTIBIOTICS
• Anti is a Greek word that means ‘against’, and bio means ‘life’, together
they mean ‘against life’ (in the context of disease causing organisms).
• ANTIBIOTICS - they are chemical substances produced by some
microbes and can kill or retard the growth of other microbes.
• Penicillin was first antibiotic to be discovered.
• Source: Eubacteria (mostly Bacillus), fungi (mostly actinomycetes),
lichens
• Antibiotics have greatly improved our capacity to treat deadly diseases
such as
 Plague,
 Whooping cough(Kaali khansi),
 Diphtheria(Gal ghotu) and
 Leprosy(Kusht rog).

25. PENICILLIN
DISCOVERY: 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.
However, 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 inWorld War II. Fleming, Chain and Florey were
awarded the Nobel Prize in 1945, for this discovery.

27. 3. CHEMICAL, ORGANIC ACIDS ,
ENZYMES AND OTHER BIOACTIVE
MOLECULES
i. CHEMICALS and ORGANIC ACIDS
ii. ENZYMES
iii. BIOACTIVE AGENTS

28. (I) CHEMICALS/ORGANIC ACIDS
Organism Category Source of
1 Aspergillus niger fungus Citric acid
2 Acetobacter
aceti
bacterium Acetic acid
3 Clostridium
butylicum
bacterium Butyric acid
4 Lactobacillus bacterium Lactic acid
5 Saccharomyces
cerevisiae
fungus Ethanol

29. ENZYMES
Enzyme Use Source microbe
1 Lipase used in laundry
detergents
Candida lipolytica
Pseudomonas
fluorescens
2 Pectinase and
protease
used in
clearing of
packed juices
Aspergillus niger
3 Streptokinase It has
fibrinolytic
effect, used as
clot buster (to
remove clots)
Streptococcus
bacterium

30. BIOACTIVE MOLECULES
COMPOUND SOURCE CATEG
ORY
USE
Cyclosporin A Trichoderma
polysporum
fungi Used as
immunosuppressive
agent (for organ
transplant patients.
Inhibits action of T
Cells
Statins Monascus
purpureus
yeast used as blood
cholesterol lowering
agents.

31. • Expand LAB
• Mention any two benefits LAB provides.
• Write the scientific name of microbe used for fermenting malted
cereals and fruit juices.
OR
Write the scientific name of baker’s yeast
• What is the medical use of Statins and Cyclosporin A?
• How does addition of small amount of curd to fresh milk help
formation of curd?
• Mention a product of human welfare obtained from:
LAB
S. cerevisae
Propionibacterium sharmanii
Aspergillus niger

32. Mention the product and its use by each of the following:
• Streptococcus
• Lactobacillus
• Sachharomyces cerevisae

34. MICROBES
IN SEWAGE
TREATMENT

35. Municipal waste composition

36. MICROBES IN SEWAGE TREATMENT
• Municipal waste water (sewage) contains large amount of
organic matter and microbes which are pathogenic
which cannot be discharged into natural water
bodies like rivers and streams.
• Sewage is treated in sewage treatment plant (STPs)
to make it less polluting by using heterotrophic
microbes naturally present in sewage. Sewage
treatment is done in two stages-
• PRIMARYTREATMENT
• SECONDARYTREATEMENT

37. PRIMARY TREATMENT
• Involves physical removal of particles.
• Done in: Grit chambers and Settling tanks
Floating debris is removed by sequential filtration.
Grit (soil and small pebbles) are removed by
sedimentation.
• All solids that settle form
the primary sludge, and the
supernatant forms the effluent.

38. SUPERNATANT AND PALLET

41. SECONDARY
TREATMENT
Activated sludge
Oxidation tanks
Trickling filter

42. SECONDARY TREATMENT
OR
BIOLOGICAL TREATMENT
• Involves passing of primary effluents in
large aeration tank where it is constantly
agitated and air is pumped into it.
• This help the vigorous growth of aerobic
microbes to form flocs.
FLOCS : masses of bacteria associated
with fungal filaments to form mesh like
structures.
• These microbes increase the digestion/
consumption of organic wastes and
decrease the BOD (Biochemical
Oxygen Demand) of the effluents.

43. SECONDARY TREATMENT
• BOD is the amount of oxygen that would be consumed
if all the organic matter in one litre of water were
oxidised by bacteria.
• It indirectly measures the amount of organic matter
present in the water. Greater the BOD of water more
it is polluted.
• Once the BOD of sewage or waste water is reduced to 10-15
%, the effluent is then passed into a settling tank where the
bacterial ‘flocs’ are allowed to sediment. This sediment is
called activated sludge.
• Activated sludge: A part of this is used as inoculum in
aeration tank. Remaining is transferred to anaerobic sludge
digester.

46. • Sludge is passed into large tanks called anaerobic
sludge digesters in which anaerobic bacteria
digest the organic mass as well as aerobic microbes
and fungi in the sludge. Methanogenic bacteria
produce a mixture of gases called biogas, which is a
mixture of methane, hydrogen sulphide and
carbon dioxide.
• The effluents from the secondary treatment plant
are released into water bodies.
• Till date, no manmade technology has
been able to rival the microbial
treatment of sewage!!!

48. SEWAGE
Primary
Effluent
Primary
Sludge
Aeration
Tanks
Secondary
Effluent
FLOCS
BOD REDUCED
Activated
Sludge
Anaerobic
Sludge
digester
Inoculum
Water Bodies
Aerobic digestion of organic waste
Biogas
PRIMARY
TREATMENT
SECONDARY
TREATMENT

49. Sewage treatment

51. Act enforced by Government to
conserve water bodies
National river conservation plan (NRCP) was enacted in
1995 to improve the water quality of the rivers, which are the
major fresh water resources in our country. This important
assignment taken up under the NRCP includes,
• To capture the raw sewage flowing into the river through
open drains and divert them for treatment.
• Setting up sewage treatment plants for treating the diverted
sewage.
• Construction of low cost sanitation toilets to prevent open
defecation on river banks.

52. THE MINISTRY FOR ENVIRONMENT, FOREST
AND CLIMATE CHANGE HAS INITIATED THE
GANGA ACTION PLAN AND THE YAMUNA
ACTION PLAN TO SAVE THE MAJOR RIVERS
OF THE COUNTRY.
• The Ganga action plan was launched on 14th January
1986. The main objective of the programme is to improve the water
quality of River Ganges by interception, diversion and treatment of
domestic sewage and to identify grossly polluting units to prevent
pollution.
• The Yamuna Action Plan is a bilateral project between the
Government of India and Japan. It was formally launched in April 1993.
It was proposed to build large number of sewage treatment plants to
discharge treated wastewater into the rivers.

55. RECALL!
• What is activated sludge?
• Explain the process of secondary treatment given to
primary effluent up to the point it shows significant
change in level of Biological Oxygen Demand (BOD)
in it.
• Explain the role of anaerobic sludge digester in
sewage treatment plant.
• Explain the steps involved in primary treatment of
sludge.
• List the events that lead to biogas production from
waste water whose BOD has been reduced
significantly.

56. • (a) How does activated sludge get produced during
sewage treatment.
(b) Explain how sludge is used in biogas production.
• What are flocs.What is their role in effluent treatment.
What is their ultimate fate?
• Determination of BOD can help in suggesting the quality
of water body. Explain.
• What are methanogens?
• Name the two categories of microbes naturally occurring
in sewage water. Explain their role in cleaning of sewage
water.
• Distinguish between the role of flocs and anaerobic sludge
digester.
-Aerobic/anaerobic
-Breakdown organic matter in primary/secondary effluent.
-biogas producton

57. • Methanogens do not produce:
a. oxygen
b. methane
c. hydrogen sulfide
d. carbon dioxide
• What would happen if oxygen availability to activated sludge
flocs is reduced?
a. It will slow down the rate of degradation of organic matter
b. The center of flocs will become anoxic, which would cause death of
bacteria and eventually breakage of flocs.
c. Flocs would increase in size as anaerobic bacteria would grow
around flocs.
d. Protozoa would grow in large numbers.

58. • The technology of biogas production from cow dung was
developed in India largely due to the efforts of:
a. Gas Authority of India
b. Oil and Natural Gas Commission
c. Indian Agricultural Research Institute and Khadi &Village Industries
Commission
d. Indian Oil Corporation.
• BOD of waste water is estimated by measuring the amount
of:
a. total organic matter
b. biodegradable organic matter
c. oxygen evolution
d. oxygen consumption.

59. • Wastewater treatment generates a large quantity of sludge, which can be
treated by:
a. anaerobic digesters
b. floc
c. chemicals
d. oxidation pond.
• .Methanogenic bacteria are not found in
(a) Rumen of cattle
(b) Gobar gas plant
(c) Bottom of water-logged paddy fields
(d) Activated sludge
• Wastewater treatment generates a large quantity of sludge, which
can be treated by
(a) Anaerobic digesters
(b) Floe
(c) Chemicals
(d) Oxidation pond

61. MICROBES IN PRODUCTION OF BIOGAS
• Biogas is a mixture of gases produced by the microbial
activity that can be used as fuel. It is a methane rich
fuel gas produced by anaerobic breakdown of biomass
with help of methanogenic bacteria.
• Methanogens: Certain bacteria that grows anaerobically on
cellulosic material produce large amount of methane along with
CO2 and traces of Nitrogen, H2S and H2. These bacteria are
collectively called methanogens (Methanobacterium).
• Methanogens are present in
1.Activated sludge (in sewage treatment)
2. Rumen of cattle

62. BIOGAS
PRODUCTION
STEP
3
Organic acids acted upon
by methanogenic bacteria
to produce methane and
CO2.
STEP
2
Simple compounds are
further converted into
organic acids by
fermentation
STEP
1
Anaerobic digestion,
enzymatic breakdown of
complex organic matter
into simpler substances

63. BIOGAS TECHNOLOGY
• The excreta of cattle (gobar) is rich in
methanogens bacteria and is used for
generation of biogas also called as gobar gas.
• The technology of biogas production was developed
in India mainly due to the efforts of Indian
Agricultural Research Institute (IARI) and
Khadi andVillage Industries Commission
(KVIC).

64. BIOGAS PLANT
• Biogas plant consists of a concrete tank (10-15ft deep)
in which bio-wastes are collected and slurry of dung is
fed.
• A floating cover is placed over digester that moves
upward when gas is produced.
• The gas produced is removed and supplied through an
outlet pipe for consumption.
• The spent slurry is removed through another outlet and
used as fertilisers.
• Biogas plant is more often build in rural areas as large
amount of cattle dug is available easily.

65. A typical Biogas Plant

67. Small scale biogas plant

68. ADVANTAGES OF BIOGAS
• Provides both energy and manure.
Manure, how?The effluent residue left after
the fermentative generation of biogas is rich in
minerals, lignin, cellulose etc and serves as
ideal manure.
• Environmental friendly: Does not add to pollution.
• Storable form: more efficient and economic.
• Minimizes the chances of spread of fecal pathogens

69. BIOGAS
Methanogens
Biofuel
Manure
Methane
CO2
H2S
Clean Fuel
IARI
KVIC
Anaerobic action

70. MICROBES IN AGRICULTURE
Biocontrol Agents

72. MICROBES AS BIOCONTROL AGENT
• Biocontrol means use of biological/biochemical
methods for controlling plant disease and
pests. The chemical used as pesticides and
insecticides are harmful to human beings and
animals.
• The natural method of pest and pathogen control
involving use of viruses, bacteria and other insects
is called biocontrol or biological control.

73. Organic farming is a technique, which involves
cultivation of plants and rearing of animals in natural ways. This
process involves the use of biological materials, avoiding synthetic
substances to maintain soil fertility and ecological balance thereby
minimizing pollution and wastage.
• Key features of organic farming
• Protecting soil quality using organic materials and encouraging
biological activity.
• Indirect provision of crop nutrients using soil microorganisms.
• Nitrogen fixation in soils using legumes.
• Weed and pest control based on methods like crop rotation,
biological diversity, natural predators, organic manures and
suitable chemical, thermal and biological interventions.
• Biofertilizers and biopesticides are used in organic
farming methods.

75. ORGANIC FARMING
• It is a farming system with minimal
or no use of chemicals as
fertilizers, herbicides, pesticides, etc.
organic manures, recycled farm-
wastes (straw and livestock excreta)
use of bio-agents such as culture of
blue-green algae in preparation of
biofertilizers,
with healthy cropping systems [mixed
cropping inter-cropping and crop
rotation].
These cropping systems are beneficial
in insect, pest and weed control besides
providing nutrients.

76. BIOLOGICAL CONTROL OF PESTS AND DISEASE
• BIOPESTICIDES : These are biological agents that are used
for control of weeds, insects and pathogen (viruses,
bacteria, protozoa, fungi etc) e.g. Bio-Insecticide
• These biological agents are grown in labs on a large scale
for commercial production.
• The organic farmer creates a system where the pests
are not eradicated but kept at manageable level by
complex system of check and balance within the living and
vibrant ecosystem.

77. • EXAMPLES OF BIOCONTROL AGENTS:
• The Ladybird and Dragonflies are used to get
rid of aphids and mosquitoes respectively.
• Bacteria: Bacillus thurengenesis
• Fungi: Trichoderma
• Virus: Baculovirus

78. 1. BACTERIA: On Brassica and fruit tree, to control
butterfly caterpillars bacteria Bacillus thuringiensis is
used.

79. Gossypium (Cotton)

80. 2. FUNGUS:
Trichoderma are free-
living fungi that are
very common in the
root systems that
control several plant
pathogens.
Trichoderma viridae
fungus has been used
to develop biological
control for the
treatment of plant
diseases.
Trichoderma spp

82. 3.VIRUS: Baculoviruses are pathogens that attack insects and other
arthropods.The majority of these belong to genus Nucleopolyhedrovirus.
These viruses are excellent candidates for species-specific, narrow
spectrum insecticidal applications.

83. BIOCONTROL AGENTS
BIOCONTROL
AGENT
MICROBE USED
AGAINST
1 Bacillus thuringiensis Bacteria Butterfly
caterpillars
2 Trichoderma Fungi Plant
pathogens
3 Baculoviruses
Nucleopolyhedrovirus
Virus Insects and
some
arthropods

84. INTEGRATED PEST MANAGEMENT (IPM)
Source: farmbiosecurity.com

87. MICROBES AS BIO FERTILISERS
Bio fertilisers are organisms that enrich the
nutrient quality of the soil. They enhance the
availability of nutrients like Nitrogen and
Phosphorous to crops.
The microorganisms that can act as biofertilizers
are:
1. Nitrogen fixing bacteria
2. Cyanobacteria
3. Mycorrhiza

88. 1. NITROGEN FIXING BACTERIA
• These fix atmospheric nitrogen and make it available for plants.
• Free living Nitrogen fixing bacteria: Azotobacter, Azospirillum
• Symbiotic Nitrogen fixing bacteria: Form symbiotic association with
plants. E.g. Rhizobium, which forms nodules on the roots of leguminous
plants
Root nodules

89. 2. CYANOBACTERIA
• Cyanobacteria are autotrophic microbes widely distributed in aquatic
and terrestrial environments.
• Many Cyanobacteria can fix atmospheric nitrogen.
• In paddy fields, cyanobacteria serve as an important biofertiliser.
• Blue green algae also add organic matter to the soil and increase its
fertility.
• Free living nitrogen fixing Cyanobacteria: Nostoc, Anabena, Oscillatoria.
• Symbiotic nitrogen fixing Cyanobacteria (BGA): Lichens, Azolla-
Anabena association and in Cycad roots.
Nostoc Collaroid root of Cycad

90. 3. MYCORRHIZA
• Symbiotic association of fungus with roots of higher plants
• Most common fungal partners: Glomus species.
• Enhanced absorption of phosphorous
• Such plants also show other benefits such as resistance to root-borne
pathogens, tolerance to salinity and drought, and an overall increase in
plant growth and development.

91. TOPICS DISCUSSED
• Microbes: Occurrence, growth, classes
• Microbes in household
• Microbes in industrial products
• Microbes in sewage treatment
• Microbes in biogas production
• Microbes as biocontrol agents
• Microbes as biofertilizers

92. Methanogenic bacteria are not found in:
a. rumen of cattle
b. gobar gas plant
c. bottom of water-logged paddy fields
d. activated sludge.
The technology of biogas production from cow dung was developed in India
largely due to the efforts of:
• a. Gas Authority of India
• b. Oil and Natural Gas Commission
• c. Indian Agricultural Research Institute and Khadi & Village Industries
Commission
• d. Indian Oil Corporation.

93. The free-living fungus Trichoderma can be used for:
• a. killing insects
• b. biological control of plant diseases
• c. controlling butterfly caterpillars
• d. producing antibiotics
• How has the discovery of antibiotics helped mankind in the field of medicine?
• How do bioactive molecules of fungal origin help in restoring good health of
humans?
• What are viruses parasitising bacteria called?
• How was penicillin discovered?
• How has the bacterium Bacillus thuringiensis helped us in controlling
caterpillars of insect pests?

94. • What is a broad spectrum antibiotic? Name one such antibiotic.

95. Amoxicillin:Ampicillin

96. • Why is distillation required for producing certain alcoholic drinks?
(Increases alcoholic content)
• What would happen if our intestine harbours microbial flora exactly similar to
that found in the rumen of cattle?
• Name any genetically modified crop.
• Which species of Penicillium produces Roquefort cheese?
• What is the group of bacteria found in both the rumen of cattle and sludge of
sewage treatment?
• Why are flocs important in biological treatment of waste water?

97. • Which of the following helps in absorption of phosphorous?
a) Glomus
b) Rhizobium
c) Anabaena
d) Nostoc
• Sugary juice --------------------- Ethanol + H2O
• Monoascus purpureus -------- A – helps in lowering blood
cholesterol
• (a) What would happen if a large volume of untreated sewage is
discharged into a river? (b) In what way anaerobic sludge digestion is
important in sewage treatments?
?

98. • Expand LAB
• Mention any two benefits LAB provides.
• Write the scientific name of microbe used for fermenting malted
cereals and fruit juices.
OR
Write the scientific name of baker’s yeast
• What is the medical use of Statins and Cyclosporin A?
• How does addition of small amount of curd to fresh milk help
formation of curd?
• Mention a product of human welfare obtained from:
LAB
S. cerevisae
Propionibacterium sharmanii
Aspergillus niger

99. Mention the product and its use by each of the following:
• Streptococcus
• Lactobacillus
• Sachharomyces cerevisae

102. THANKYOU
B H O O M I K A