Mutualism is a symbiotic relationship where two populations benefit from each other's existence, often leading to obligatory interactions and the evolution of new organisms. Examples include lichens formed from fungi and algae, bees pollinating flowers while collecting nectar, and nitrogen-fixing bacteria aiding leguminous plants. These interactions illustrate the interconnectedness of species for survival and resource sharing.

1. Presentation by:
A.Abinaya Kalyani
III B.Sc Microbiology

3. Mutualism occurs on the association of two
populations in which there occurs a close and
often permanent and obligatory contact, where
both the populations are benefitted is called
mutualism.
The term mutualism was first coined by Debary
(1877) and literally means ‘living together’.

4. Mutualism (latin mutus means borrowed) defines the relationship between two
organisms which are mutually benefitted.
The relationship is an obligatory relationship.
Mutualism may lead to evolution of new organisms.
This interaction happens between two organism when they are in need of resources
such as food, light and space.
The organisms which are in mutualistic relationship metabolically depend on each
other.
When the organisms in this interactions are seperated they will not survive.

5. The mutualistic organisms lose their individuality and become a single
organism. Some of the relationships are explained below:
Lichens are organisms of symbiotic association in which
a highly specialised fungal partner (mycobiont) inhabits
in itself an algal patner (phycobiont).
It is a thallus of undifferentiated tissues because of two
symbionts.
The fungal component mostly belong to class
Ascomycetes.

6. Lichens are cosmopolitan in distribution, found in varied habitats from
mountain tops to sea shores based on which they are of three different types:
Saxicoles which grow on rocks, usually in cold areas.
Corticoles which grow on barks of trees usually in the tropical and
subtropical areas.
Terriclies which grow in soil, in hot areas.

7. Saxicoles Corticoles Terriclies

8. Here algae and protozoa exhibit mutualism.
Paramaecium hosts Chorella within its cytoplasm. Presence of chorella allows the
protozoan to move into anaerobic habitats as long as there is sufficient light.
The foraminiferans (protozoa) lodge pyrrophycophycean members (red algae) within
their cells. The algae import red colour to the protozoans and each protozoan can
contain about 50-100 algal cells.
There are few bacterial symbionts within protozoans.
Endosymbiotic methanogens have been found in anaerobic ciliate protozoans living
within the rumen, for example, Methanobacterium, Methanocarpusculum and
Methanoplanus.They faclitate material exchange between the protozoan membranes
and the bacterias

9. Zoochlorellae
Protozoa
Red algae

10. Rumen bacteria in a deer stomach
allow the deer to digest cellulose
while the bacteria grow in warm
environment.

11. Bees collect nectar from flowers which
they make into food. When they land on
the flower they get pollen stuck to their
bodies. They spread this pollen to other
flowers, pollinating the plants.

12. The nitrogen fixing bacteria
(Rhizobium) that live in the nodules of
the roots of the leguminous plants.

13. Bacteria lives in the intestines of humans.
The bacteia helps the human by digesting
food that the human cannot. They get a
meal and the humans able to digest the
food.

14. In Conclusion, somehow all creatures are related together,
directly and indirectly.
Mutualism is the way of two or more species cooperate
together to survive.