Bacterial spores are dormant, resistant structures formed by certain bacteria under stressful conditions. They have a thick coat that allows them to survive extreme heat, lack of water, toxins, and radiation. There are two types of spore formation: endospores form inside the parent cell while exospores bud off externally. Endospores contain dipicolinic acid which makes them highly resistant. Germination occurs in three stages - activation by damage to the coat, initiation by effectors in a rich environment, and outgrowth involving degradation of spore layers and emergence of a new vegetative cell.

1. Dr. B. Lal Institute of Biotechnology
Bacterial spores
By :- Mumal
Kanwar
Mertiya
From :- b.sc. Biotech part 1st
Teacher in-charge
:- Miss Rinki
Sharma Ma’am

2. Contents:-
*Definition
*Structure
*Formation
* Germination of bacterial
spores..

3. What is bacterial spores…?
Bacterial spores are the dormant
forms of bacterial structure which
are thick walled , highly refractile
and resistant.

4. Spore structure :
Spore formation is a means by which some bacteria haulting their
vegetative phases produces structure that are able to survive in
extremely harsh environmental conditions.

5. Shapes
• Spherical , oval or elongated in shape.
• May be narrower or broader(bulge) than parent cell.
(1) (2)

6.  Bacterial spores undergoes two types
of formation :-
Bacterial spores
Endospore Exospore

7. o Endospore;
 Endospores are highly durable dehydrated cells,
which can survive extreme heat, lack of water,
freezing and exposure to many toxic chemicals
and radiation.
 Endospores also called as “resting cells”.
 Formed outside the vegetative cell by budding at one end
of the cell.
 Formed inside the parent vegetative cell.
 The Exospore do not contain dipicolinic acid.
 They can resist desiccation and
heat.
o Exospore ;

8. Formation :
 Exospores are formed external to the
vegetative cell by budding at one end
of the cell . Members of the genus
methylosinus and strains of the
photosynthetic bacterium
rhodomicrobium produce exospores
.these are heat dessication and UV
resistant . Is initiated by the
appearance of the bud like
enlargement and surrounding capsule
at one end .

9. • Endospore formation :
When certain essential elements like
carbon ,nitrogen and phosphorus are
limited or completely depleted or
when water is unavailable certain
gram (+) bacilli from specialized
resting cells called endospores.
These endospores are highly durable
dehydrated cells which can survive
extreme heat, lake of water, freezing
and exposure to many toxic
chemicals and radiation . The genera
of bacteria giving rise to endospore

10.  Germination
The germination process
occurs in three stages:
◦Activation
◦Initiation
◦Outgrowth.

11.  Activation
 Even when placed in an environment that
favors germination (eg. nutritionally rich
medium) bacterial spores will not
germinate unless first activated by one or
another agent that damages the spore
coat.
 Among the agents that can overcome
spore dormancy are heat, abrasion,
acidity, and componds containing free
sulfhydryl groups.

12.  Initiation
 Once activated, a spore will initiate germination if
the environmental conditions are favorable.
 Different species have evolved receptors
recognise different effectors as signaling a rich
medium.
 Binding of the effector activates an autolysin that
rapidly degrades the cortex peptidoglycan. Water
is taken up, calcium dipicolinate is released, and a
variety of spore constituents are degraded by
hydrolytic enzymes.

13.  Degradation of the cortex and outer layers
results in the emergence of a new
vegetative cell consisting of the spore
protoplast with its surrounding wall.
 A period of active biosynthesis follows. This
period, which terminates in cell division, is
called outgrowth.
 Outgrowh requires a supply of all nutrients
essenial for cell growth.
 Out growth