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Online Counseling Resource
YCMOU ELearning Drive…
School of Architecture, Science and Technology
Yashwantrao Chavan Maharashtra
Open University, Nashik – 422222, India
OC-SEP041-CP01-05
Introduction
Programmes and Courses
 SEP – SBT041 – Unit 01
 SEP – SBI041 – Unit 01
 SEP – SGS041 – Unit 01
School of Science and Technology, Online Counseling Resource…
Credits
 Academic Inputs by
 Mrs. Rasika Bhore
 M.sc (Microbiology)
 [email protected]
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School of Science and Technology, Online Counseling Resource…
How to Use This Resource

Counselor at each study center should use this presentation to deliver
lecture of 40-60 minutes during Face-To-Face counseling.

Discussion about students difficulties or tutorial with assignments should
follow the lecture for about 40-60 minutes.

Handouts (with 6 slides on each A4 size page) of this presentation should
be provided to each student.

Each student should discuss on the discussion forum all the terms which
could not be understood. This will improve his writing skills and enhance
knowledge level about topics, which shall be immensely useful for end
exam.

Appear several times, for all the Self-Tests, available for this course.

Student can use handouts for last minutes preparation just before end
exam.
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School of Science and Technology, Online Counseling Resource…
Learning Objectives
 After studying this module, you should be able to:
 Discuss the struggle for existence by the
formation of Endospores by bacteria.
 Describe the germination of endospore back to
vegetative form.
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School of Science and Technology, Online Counseling Resource…
Introduction
 A bacterial structure sometimes observed as an inclusion is
actually a type of dormant cell called an endospore.
 Endospores are formed by a few groups of bacteria as
intracellular structures, but ultimately they are released as
free endospores, a fascinating type of cell.
 Endospores exhibit no signs of life, being described as
cryptobiotic.
 Although cryptobiotic, they retain viability indefinitely such
that under appropriate environmental conditions, they
germinate back into vegetative cells.
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School of Science and Technology, Online Counseling Resource…
Endospores
 Endospores are probably the most durable cell produced in
nature.
 They are formed by vegetative cells in response to
environmental signals that indicate a limiting factor for
vegetative growth, such as depletion of an essential nutrient.
 They are highly resistant to environmental stresses such as
high temperature, irradiation, strong acids, disinfectants, etc.
 Endospores are commonly found in soil and water, where they
may survive for long periods of time.
 Some bacteria produce exospores or cysts instead.
 Endospores germinate and become vegetative cells when the
environmental stress is relieved.
 Hence, endospore formation is a mechanism of survival rather
than a mechanism of reproduction.
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School of Science and Technology, Online Counseling Resource…
Endospore Forming Bacterial Genera
 Bacillus(B.anthracis, B.cereus, B. subtilis)
 Clostridium (Cl.tetani)
 Desulfotomaculum
 Sporolactobacillus
 Sporosarcina
 Thermoactinomyces
Endospores of different species
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School of Science and Technology, Online Counseling Resource…
Stages of Endospore Formation
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School of Science and Technology, Online Counseling Resource…
Stages of Endospore Formation-2
 When the environmental conditions becomes unfavorable
bacteria starts sporulation, which takes about eight hours.
 The DNA is replicated and a membrane wall known as a spore
septum begins to form between it and the rest of the cell.
 The plasma membrane of the cell surrounds this wall and
pinches off to leave a double membrane around the DNA, and
the developing structure is now known as a forespore.
 Calcium dipicolinate is incorporated into the forespore during
this time.
 Next the peptidoglycan cortex forms between the two layers
and the bacterium adds a spore coat to the outside of the
forespore.
 Sporulation is now complete, and the mature endospore will
be released when the surrounding vegetative cell is degraded.
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School of Science and Technology, Online Counseling Resource…
Mature Endospore
 The spore has a core
wall of unique
peptidoglycan
surrounded by several
layers, including the
cortex, the spore
coat and the
exosporium.
 The dehydrated core
contains the bacterial
chromosome and a
few ribosomes and
enzymes to jump-start
protein synthesis and
metabolism during
germination.
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School of Science and Technology, Online Counseling Resource…
Functions of Structural Components
 Spore coat is impermeable to many toxic molecules and
contain enzymes that are involved in germination.
 The core has normal cell structures, such as DNA and
ribosomes, but is metabolically inactive.
 The spore cell also contains small acid-soluble spore proteins
(SASPs) to protect DNA from UV radiation, desiccation and dry
heat, and they also serve as a carbon and energy source
during the germination process.
 Up to 15% of the dry weight of the endospore consists of
calcium dipicolinate within the core, which is thought to
stabilize the DNA.
 Dipicolinic acid believed to responsible for the heat
resistance of the spore, and calcium may aid in resistance to
heat and oxidizing agents but mutants resistant to heat but
lacking dipicolinic acid have been isolated.
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School of Science and Technology, Online Counseling Resource…
Types of Endospores
 Various types of endospores are accounted depending on their
positions.
 The main types within the cell are: terminal, lateral and
centrally placed endospores.
 Terminal endospores are seen at the poles of cells (1,4)
 Central endospores are more or less in the middle
(2,3,5)
 Lateral endospores are those between these two
extremes, usually seen far enough towards the poles but
close enough to the center so as not to be considered
either terminal or central (6)
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School of Science and Technology, Online Counseling Resource…
Bacteria Having Different Endospores
 Bacteria having terminal endospores include Clostridium
tetani, the pathogen which causes the disease tetanus.
 Bacteria having a central endospore include Bacillus cereus,
and
 Those having a subterminal endospore include Bacillus
subtilis.
 Sometimes the endospore can be so large the cell can be
distended around the endospore, this is typical of Clostridium
tetani.
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School of Science and Technology, Online Counseling Resource…
Destruction of Endospores
1. Alkylating agents such as ethylene oxide, is
effective against endospores.
2. Though resistant to extreme heat and radiation,
endospores can be destroyed by burning or
autoclaving.
3. Exposure to extreme heat for a long enough period
will generally have some effect, though many
endospores can survive hours of boiling or cooking.
4. Prolonged exposure to high energy radiation, such
as x-rays and gamma rays, will also kill most
endospores.
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School of Science and Technology, Online Counseling Resource…
Germination of Endospores
 When conditions are favorable reactivation of endospore starts
involves activation, germination, and outgrowth.
 Even if an endospore is located in plentiful nutrients, it may
fail to germinate unless activation has taken place which may
be triggered by heating the endospore.
 Germination involves the dormant endospore starting
metabolic activity and thus breaking hibernation.
 It is characterised by rupture or absorption of the spore coat,
swelling of the endospore, an increase in metabolic activity,
and loss of resistance to environmental stress.
 Outgrowth involves the core of the endospore manufacturing
new chemical components and exiting the old spore coat to
develop into a fully functional vegetative bacterial cell.
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School of Science and Technology, Online Counseling Resource…
Differences Between Endospore & Vegetative
Cell
Property
Vegetative cells
Endospores
Surface coats
Typical Gram-positive murein
cell wall polymer
Thick spore coat, cortex, and
peptidoglycan core wall
Microscopic appearance
Nonrefractile
Refractile
Calcium dipicolinic acid
Absent
Present in core
Cytoplasmic water activity
High
Very low
Enzymatic activity
Present
Absent
Macromolecular synthesis
Present
Absent
Heat resistance
Low
High
Resistance to chemicals and
acids
Low
High
Radiation resistance
Low
High
Sensitivity to lysozyme
Sensitive
Resistant
Sensitivity to dyes and
staining
Sensitive
Resistant
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School of Science and Technology, Online Counseling Resource…
What We Learn………….
 Endospores are cryptobiotic & highly resistant to heat &
radiations.
 Commonly found in soil & water.
 Early stage of endospore formation involves partition of
chromosome & ribosome in mother cell.
 Late stage involves formation of several layers i.e. cortex,
spore coat, spore wall.
 Mature endospore contain calcium dipicolinic acid supposed
to role in heat resistance.
 Three types of endospores are terminal, subterminal &
central.
 Endospore germination is carried our by rupture of spore
coat & manufacturing of new chemical components.
 Differences between endospores & vegetative cell.
School of Science and Technology, Online Counseling Resource…
Critical Thinking Questions
 What is the medical significance of
endospore forming bacteria?
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School of Science and Technology, Online Counseling Resource…
Tips For Critical Thinking Questions
 Treatment of bacterial infection depend
on whether the infecting pathogen is able
to form spores.
© 2007, YCMOU. All Rights Reserved.
School of Science and Technology, Online Counseling Resource…
Study Tips
 Book

Title: Microbiology

Author: L. M. Prescott
 Book

Title: Introduction to
Microbiology

Author: J. L. Ingraham
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School of Science and Technology, Online Counseling Resource…
Study Tips
www.en.wikipedia.org
Endospores
www.cals.cornell.edu
Bacterial endospores
© 2007, YCMOU. All Rights Reserved.
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End of the Presentation
Thank You !