This ppt includes all the various important aspects of bacteria in Agricultural purposes. Bacteria are found everywhere.The soil provides a favourable environment for various microorganisms, including bacteria, fungi, viruses, and protozoa. Therefore, these microbes are abundantly and sometimes densely found in the soil. It is estimated that there are almost one to ten million microorganisms per gram of soil. Among all these microorganisms, bacterias and fungi are the most common. All these microorganisms in the soil interact with each other to create constantly altering conditions. The interactions between these multiple factors are responsible for various types of soil in a particular place and constitute a distinct branch of agriculture microbiology called soil microbiology. The agricultural industry consists of anything grown or raised for human use, such as livestock, lumber, flowers, and harvesting plants to feed or sell, etc. It is one of the oldest industries in the world, almost thousands of years old. The agricultural industry has changed a lot in the last 100 years. Now, agriculturalists can grow more crops in small spaces. The cost of farming is reduced. Advance study in soil microbiology and biotechnology has brought many changes in agriculture like better quality and quantity crops, improvement in soil fertilisation, etc.

1. Laiba Noor
Roll. No. (45)
IMPORTANCE OF BACTERIA
IN AGRICULTURE

2. BACTERIA AND IT’S OCCURRENCE:
 Bacteria are the unicellular prokaryotic
organisms classified as microorganisms
that lack membrane bound organelles.
 The bacteria occupy many environments
such as air, soil, water, in and on Living
organisms ( plants and animals), they can
even found in hot springs at temperature
70°C or higher.

3. IMPORTANCE OF BACTERIA WITH REFERENCE TO
AGRICULTURE:
Role in Soil fertility
Role in Nitrogen fixation
Role in Decay and Decomposition
Role in Phosphate fixation
Bacteria are also important in making important
biological
 products which are as follows:
Biofertilizers
Biopestisides
Bioinsecticides
Green manure
Biogas
Conclusion

4. 1. ROLE OF BACTERIA IN SOIL FERTILITY:
 Microbs, especially bacteria play very significant role in the
agricultural field.
 Bacteria play important role in maintaining and increasing soil
fertility.
 Bacteria increase soil fertility through Nutrient cycling such as carbon,
nitrogen,
 phosphorus and sulphur.
 The fertility of soil is proportional to its nitrogen content. Nitrogen is
an essential
 Ingredient of all living protoplasm.
 So, soil bacteria play important role in Nitrogen cycling, phosphate
cycling etc
 making the soil fertile and suitable for the growth of plants.
 EXAMPLE: Rhizobium, Azotobacter, Azospirillum.

5. 2. ROLE OF BACTERIA IN NITROGEN FIXATION:
About 78% of our atmosphere consist of nitrogen. But plants are unable to use
this atmospheric nitrogen in 8ts element form. They use it in the form of
nitrates, nitrites or ammonia from the soil.
NATURE’S FARMERS:
In nature, a regular supply of nitrogenous salts is ensured by bacteria of
certain types, such as ammonifying bacteria, nitrifying bacteria, and nitrogen-
fixing bacteria.
Ammonifying bacteria are known to release ammonia from protein, e.g.,
Bacillus vulgaris, B. Ramosus, etc. Soil ammonia is trapped as ammonium
salts and available for plant absorption.

6. CONTI……..
• There are two types of nitrifying bacteria in the soil; Nitrite bacteria that
convert ammonium nitrogen into nitrites (e.g., Nitrosomonas, Nitrosococcus,
etc.), and Nitrate bacteria which transform nitrites into nitrates (e.g.,
Nitrocystis).
• This transformation of atmospheric nitrogen into nitrogenous compounds that
can be used by plants is called nitrogen fixation..
• A series of changes through which nitrogen passes due to the activities of these
bacteria constitute the nitrogen cycle.

7. Three events in Nitrogen
cycle:
1. Ammonification
2. Nitrification
3. Denitrification
• Nitrogenase enzyme is controlling the whole
reaction.

9. TYPES OF NITROGEN-FIXING BACTERIA:
There are the following two types of Nitrogen-fixing bacteria.
Free- living ( non-
symbiotic) bacteria
Mutualistic (symbiotic)
bacteria
e.g.,Rhizo-bium
e.g.,Azotob-
acter,
Clostridium

11.  The symbiotic nitrogen-fixing bacteria invade the root
hairs of host plants, where they multiply and stimulate
formation of root nodules ( enlargements of plant cells).
Within the nodules the bacteria convert free nitrogen to
ammonia, which the host plant utilizes for its
development and further processes.
 EXAMPLES: Rhizobium leguminosarum which is
associated with plants in the pea family (like pea, bean,
medicago and others )and various Azospirillum species,
which are associated with cereal grasses.

12. NITRIFYING BACTERIA:
The nitrifying bacteria convert nitrogen from the unavailable form of
ammonium salts to the available nitrates. This process converting unavailable
ammonium salts into available nitrates is called nitrification.
Ammonia is very soluble. It moves in the soil rapidly and is acted upon by
microorganisms of the category of chemosynthetic autotrophs in the soil. They
are the nitrifying bacteria such as Nitrosomonas and Nitrobacter.
They form nitrates from ammonium compounds.

13. CONTI……
This reaction takes place in the following two steps:
 NH4 + 2O2 2H2O + NO2+ energy ( Nitrosomonas)
 NO2- + ½ O2 NO3- + energy ( Nitrobactor)
 Nitrosomonas oxidizes ammonium carbonate to nitrous acid liberating energy.
The nitrous acid then combines with bases in the soil forming potassium
nitrite. Nitrobacter oxidizes nitrites to nitrates again liberating energy.

14. The nitrifying bacteria get their energy from
oxidation of
 inorganic nitrogen compounds.
Example Of Nitrifying bacteria: Nitrosomonas,
Nitrosococcus,
Nitrobacter, Nitrospina, Nitrospira and
Nitrococcus.

15. 3. ROLE IN DECAY AND DECOMPOSITION:
Remove harmful substances from earth( as scavenger)
Return it to soil as nutrients to plants.

16. BACTERIAL PRODUCTS USED IN AGRICULTURE:
1. BIOFERTILIZERS
Substances containing
microorganisms that increase the
fertility of soil and promote plant
growth supplying essential nutrients
when added to soil.
Main constituent of Biofertilizers are
living microbes like algae, bacteria
and fungi. They can be alone or in
combination.

17. 2. BIOPESTISIDES:
The soil also has plant pathogenic bacteria present in the rhizospheric zone, and it can
cause a lot of diseases in the plant.
 Using these pathogenic microbes, researchers have made a biological tool to control
unwanted weeds and pests called biopesticides.
These microbes possess genes that are invasive and can attack the weeds and kill them.
For example, the bacterium Bacillus thuringiensis produces toxic proteins that kill certain
insects but are harmless to humans.
 Bacillus popillae (milky spore disease) can kill Japanese beetle larvae.

19. 3. BIOINSECTICIDES
The most widely used Bt insecticides are formulated from
Bacillus thuringiensis var. Kurstaki can kill larvae of
butterflies and moths. They are also used to control many
common leaf-feeding caterpillars.
(Pesticide’ is the general term for a chemical that kills pests.
Pests can be weeds, insects, nuisance rodents, diseases, etc.
An insecticide is a type of pesticide. Insecticides kills
insects.
EXAMPLES OF INSECTICIDES:
Mode of
action
Examples Control
agent
Produce
toxins
Bacillus
thuringiens
is
Lepidopter
ans
that are
detrimenta
l to certain
insect
pests
Bacillus
popillae
Japanese
beetles
when
ingested. Agrobacter
ium
radiobacte
r
Crown gall
disease

20. 4. GREEN MANURE:
 Green manure is produced by leaving uprooted, sown crops and their parts to wither
on a field so that they act as a mulch and soil amendment.
 Heterotrophic bacteria that consume organic matter are used to break down green
manure into plant nutrient components.
 These are added for the purposes such as building soil organic matter and soil
structure, supplying nitrogen and other essential nutrients to crops to prevent
leaching of soluble nutrients from the soil, preventing damage to soil structure by
providing ground cover, etc.
 Hence, green manures usually perform multiple functions such as soil
improvement, soil protection, etc.

22. 5. BIOGAS:
 Biogas is an example of renewable fuel obtained by the decomposition of organic
matter like plant wastes, food scraps, animal waste, etc.
 It is actually a mixture of gases released by microorganisms during
decomposition.
 Methane is the primary and main biogas.
There are certain bacteria that grow well under anaerobic conditions and produce a
large amount of methane along with carbon dioxide and hydrogen.
The bacteria that produce the gaseous mixture are called methanogens.
EXAMPLE: Methanobacterium is an example of methanogen. It is found inside the
rumen of the cattle and the sludge produced during sewage treatment.

23. CONCLUSION:
Bacteria play a very important role in the
agricultural field.
Bacteria help in the decay or decomposition of
organic matter in the soil.
They can help in increasing soil fertility and also
promote plant growth.
 Various bacterial products such as biofertilizers,
biopesticides, and bioinsecticides are also used in
agriculture instead of chemical products

24. THANK YOU!