INDEX

S.NO CONTENT

1. Introduction

2. Microorganisms Involved In Composting

3. Stages Of Composting And Microbial Activity

4. Microbial Succession In Composting

5. Biochemical Role And Enzymatic Activities

6. Factors Affecting Microbial Composting

7. Microbial Inoculants

8. Effective Microorgaisms

9. Application In Agriculture

10. Case Studies

11. Conclusion

12. Bibliography
Introduction
Composting is a natural biological process that
transforms organic waste into a nutrient-rich soil
amendment known as compost. This process is
driven primarily by a diverse community of
microorganisms, including bacteria, Fungi,
actinomycetes, and other microbes. These
microorganisms play a Critical role in breaking down
complex organic materials, facilitating nutrient
Cycling, and ultimately improving soil health.
Understanding the role of Microorganisms in
composting is crucial for optimizing compost
production And enhancing its benefits to agriculture
and the environment. Grass clippings are an
excellent source of nitrogen for composting. They
decompose quickly, add moisture and bulk, and
improve the pile's structure and aeration.These
microorganisms work together in a complex web of
interactions to break down organic matter and make
it available to plants.
 Bacteria

Actinomycetes
Microorganisms Involved In
Composting
Bacteria: The most abundant and active
decomposers, bacteria Dominate all stages of
composting. They are responsible for the initial
Breakdown of simple organic compounds such as
sugars, starches, and Proteins.

Fungi: Essential for decomposing more complex

carbon compounds like cellulose and lignin found in
plant cell walls. Fungi thrive especially in the later
stages of composting when the material is drier and
more recalcitrant.

Actinomycetes: A group of filamentous bacteria that

share characteristics of both bacteria and fungi. They
play a key role in breaking down tough, woody
materials and produce the earthy smell associated
with healthy compost.

Other Microorganisms: Protozoa, nematodes, and

microarthropods contribute to the process by
feeding on bacteria and fungi, further fragmenting
organic matter and regulating microbial populations.
Stages Of Composting And Microbial
Activity
(1) MESOPHILIC PHASE

This initial phase occurs at moderate temperatures

(20-45°C). Mesophilic bacteria rapidly multiply and
consume readily degradable organic compounds
such as sugars and proteins, producing heat as a by-
product.During this phase, microbial populations
grow exponentially, increasing oxygen consumption
and carbon dioxide production.

(2) THERMOPHILIC PHASE

As temperature rises above 45°C, thermophilic

bacteria and actinomycetes dominate. This phase
can reach temperatures between 50-70°C, which
helps in destroying pathogens and weed seeds.
Thermophilic microbes break down more complex
compounds like cellulose and hemicellulose,
accelerating decomposition. The heat generation
during this phase is crucial for sanitizing the
compost.
(3) COOLING PHASE

Once the readily degradable material is consumed,

temperatures decline, and the compost enters the
cooling or maturation phase. Mesophilic
microorganisms re-colonize, and fungi become more
active in digesting lignin and other resistant
compounds. This phase prepares the compost for use
in soil by stabilizing organic matter.

(4) MATURATION PHASE

In this final phase, microbial activity slows down,

and the compost stabilizes. Complex humic
substances form, and the microbial community
reaches a balanced state. Mature compost is dark,
crumbly, and rich in nutrients.
Microbial Succession In Composting

Microbial succession in composting is a natural

process where different microbial communities
replace each other over time, driven by changing
environmental conditions like temperature and
available substrates. This succession is a key factor
in the decomposition of organic matter during the
composting process. As composting progresses, the
environment within the compost pile changes
significantly. For example, temperature increases
during the thermophilic phase, and nutrient
availability shifts as different organic compounds
are broken down. These changes favor different
microbial groups. The numbers of microorganisms
present during the composting process, driven by
shifts in temperature and nutrient availability. This
process is crucial for breaking down organic matter
and producing nutrient-rich compost. Microbial
succession ensures the efficient breakdown of
various organic materials into stable humus.
Biochemical Role And Enzymatic
Activities
DECOMPOSITION OF NUTRIENT RECYCLING
ORGANIC MATTER

Microbes break down Nutrients like nitrogen

complex organic (N), phosphorus (P), and
compounds into simpler potassium (K) are
compounds like CO₂, released and made
water, ammonia, and available for plant
humus. uptake.

BIOCHEMICAL
ROLE
HUMUS FORMATION HEAT GENERATION

Stable organic matter Microbial metabolism

(humus) is formed, produces heat, raising
improving soil compost temperature
structure and fertility. and killing pathogens
and weed seeds.
Cellulase

Phosphatase

Urease
ENZYMATIC ACTIVITIES
Enzyme Function Source

Breaks down cellulose

Cellulase Bacteria, fungi
(plant cell walls)

Degrades lignin (tough Fungi (e.g.,

Ligninase
plant material) white rot)

Breaks down proteins

Protease Bacteria, fungi
into amino acids

Decomposes fats and

Lipase oils into fatty acids and Bacteria, fungi
glycerol

Converts starches into

Amylase Bacteria, fungi
simple sugars

Converts urea into

Urease Bacteria
ammonia and CO₂

Releases phosphate
Phosphatase from organic Bacteria, fungi
compounds
Factors Affecting Microbial Composting

1 TEMPERATURE
Microorganisms involved in
composting thrive in warm
conditions (mesophilic: 20–40°C,
thermophilic: 50–70°C).
High temperatures accelerate
decomposition and kill pathogens.

MOISTURE CONTENT 2
Ideal range: 50–60%.

Too little moisture slows microbial

activity; too much causes anaerobic
conditions.

3 OXYGEN (AERATION)
Aerobic microbes need oxygen to
break down organic matter
efficiently.
Proper turning or aeration prevents
foul odors and speeds up
composting.
4 C : N RATIO
Optimal ratio of Carbon to Nitrogen:
around 25 : 1 or 30 : 1
Carbon sources (e.g., dry leaves)
provide energy, while nitrogen
sources (e.g., food waste) help build
proteins.

5
PH LEVEL
Ideal range: 6.5–8.

Extreme pH levels inhibit microbial

activity.

6 PARTICLE SIZE
Smaller particles have more surface
area for microbial action.

However, overly fine particles may

reduce air flow.

MICROBIAL DIVERSITY 7
A variety of bacteria, fungi, and
actinomycetes are needed to break
down all types of organic matter.
Avoid adding chemicals or antibiotics
that kill microbes.
Microbial Inoculants

Microbial inoculants are living microorganisms,

often bacteria or fungi, used in agriculture to
improve plant health and growth. These inoculants
act as biofertilizers, biocontrol agents, or
biostimulants, promoting plant growth, nutrient
uptake, and disease resistance. They offer a more
sustainable alternative to chemical fertilizers and
pesticides, reducing environmental impact and
improving soil health. They are a sustainable
alternative to chemical fertilizers and pesticides,
contributing to improved soil health and crop
quality. Microbial inoculants contribute to
sustainable agriculture by reducing reliance on
chemical inputs, improving soil health, and
enhancing crop productivity. They are used in
various crops like soybean, maize, rice, and common
beans. Examples : Azolla (aquatic fern) with
cyanobacteria (Anabaena) for nitrogen fixation in
rice, Bradyrhizobium japonicum for soybean.
Effective Microorganisms
E.M. is a combined culture of aerobic
microorganisms (requiring oxygen to survive)
and anaerobic (requires no oxygen to survive)
that co-exist together to the mutual advantage of
both (symbiosis).

E.M combines with the existing microorganisms

within the soil. They work together to build a
healthy living soil.

E.M is not toxic or pathogenic and is safe for

humans, animals and the environment.

This improves the soil quality and health, which

improves the growth, yield, and quality of crops.
In the variant being tested at ICIMOD ( The
International Centre for Integrated Mountain Of
Development) it is combined with composting, to
make an easy to prepare and very effective
organic fertilizer.

EM technology is used to enhance the

composting process and improve the quality of
the final compost product. .
Composting
Application In Agriculture

In agriculture, composting plays a vital role by

converting organic farm waste into nutrient-rich
compost that enhances soil fertility and structure.
The application of compost improves soil aeration,
water-holding capacity, and microbial diversity,
leading to better crop productivity and
sustainability. It reduces the need for chemical
fertilizers, thus lowering input costs and minimizing
environmental pollution. Compost enriched with
microbial inoculants can further enhance nutrient
availability and suppress soil-borne diseases, making
it a key component of organic and sustainable
farming practices.It also helps in recycling
agricultural residues effectively, reducing farm
waste. Compost supports carbon sequestration,
contributing to climate change mitigation. Compost
can be integrated into various farming systems,
including crop rotations, livestock integration, and
agroforestry. By reducing reliance on synthetic
fertilizers and pesticides, composting contributes to
more sustainable farming practices. Overall,
composting is an eco-friendly practice that promotes
long-term agricultural health and productivity.
Case Studies
(1) Composting Municipal Solid Waste Using
Microbial Inoculants

Municipal solid waste (MSW) contains a mix of

biodegradable and non-biodegradable materials.
Traditional composting is slow and often
inefficient.

Researchers introduced specific bacterial strains

like Bacillus subtilis and fungi like Trichoderma
viride as inoculants to MSW piles.

Faster temperature rise to thermophilic range

(50-65°C) within 3 days. Higher rate of organic
matter degradation (up to 45% faster).Reduced
foul odors and pathogen levels.

Outcome: This bioaugmentation improved

compost quality and reduced processing time
from 90 days to about 45-50 days.
(2) Use of Actinomycetes in Agricultural
Waste Composting

Crop residues like straw and husks are rich in

lignin and cellulose, which are hard to
decompose.

Actinomycetes species were isolated and

cultured to inoculate compost heaps of
agricultural residues.

Actinomycetes efficiently degraded cellulose and

lignin.Enhanced humus formation and nutrient
release (especially nitrogen and phosphorus).
Improved soil microbial diversity when compost
was applied.

Outcome: The inoculated compost improved soil

fertility and crop yield in test fields.

This makes them valuable for bioremediation,

helping to clean up contaminated sites and
improve environmental quality.
(3) Fungal Role in Composting Coffee Pulp

Coffee pulp contains high lignin content and

caffeine, making natural decomposition slow and
problematic.

Fungi such as Phanerochaete chrysosporium (a

white-rot fungus) were used for bio-treatment
before composting.

Fungal treatment reduced lignin content by 40%

in the first two weeks.Coffee pulp composting
time reduced from 90 days to 60 days. Final
compost was rich in nutrients and safe for use in
coffee plantations.

Fungal activity contributes to the overall quality

of the compost by increasing nutrient
availability and improving the physical structure
of the final product.

Outcome: Farmers benefited from faster

turnaround and enhanced soil quality.
Conclusion
Microorganisms play a crucial role in composting by
efficiently breaking down complex organic waste
into simpler, nutrient-rich humus. Their enzymatic
activity accelerates decomposition, eliminates
harmful pathogens, and enhances soil fertility. By
supporting microbial growth through proper
aeration, moisture, and temperature control,
composting becomes a natural, eco-friendly, and
sustainable method of waste management.These
microorganisms not only reduce the volume of
waste going to landfills but also contribute to
sustainable agriculture by improving soil health and
crop productivity. Inoculating compost with specific
microbial cultures can enhance the decomposition
rate, shorten composting time, and improve the
overall efficiency of the process. Further research
into the microbial communities involved in
composting can lead to more sustainable and
efficient composting practices. Thus,
microorganisms are the invisible engineers that
transform waste into wealth, making them essential
for effective composting.
Bibliography

https://midwestbiosystems.com/the-role-of-
microorganisms-in-the-composting-process/

https://compost.css.cornell.edu/microorg.html

https://www.tsijournals.com/articles/compostin
g-and-microbiological-additive-effects-on-
composting.pdf

https://www.slideshare.net/slideshow/effective-
microorgaisms-in-composting/242875502

https://www.vigyanvarta.in/adminpanel/upload
_doc/VV_0624_46-C.pdf

https://www.tsijournals.com/articles/compostin
g-and-microbiological-additive-effects-on-
composting.pdf