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Endospores

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by

mahmoud elnewehy

on 1 April 2014

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Transcript of Endospores

-Spores stained by special stains , they appear unstained areas by Gram stain.
-The medical importance of endospores is due to their resistance to heat.So sterilization can't be done by boiling . It can be done by
autoclaving
at
121 c for 30 minutes
-Sporulation
isn't a mean of reproductio
n , as one cell produce one spore that germinate again into one cell
structure
The outer proteinaceous coat surrounding the spore provides much of the chemical and enzymatic resistance
-Spores stained by special stains , they appear unstained areas by Gram stain.
-The medical importance of endospores is due to their resistance to heat.So sterilization can't be done by boiling . It can be done by autoclaving at 121 c for 30 minutes
-Sporulation isn't a mean of reproduction , as one cell produce one spore that germinate again into one cell
-As a cell begins the process of forming an endospore, it divides asymmetrically (
Stage II
)
-This results in the creation of two compartments, the larger
mother cell
and the smaller
forespore
. These two cells have different developmental fates
-Next the peptidoglycan in the septum is degraded and the forespore is engulfed by the mother cell, forming
a cell within a cell
(
stage III
)
Endospore Development
Endospores
Beneath the coat resides a very thick layer of specialized peptidoglycan called
the cortex
. Proper cortex formation is needed for dehydration of the spore core, which aids in resistance to high temperature
A germ cell wall resides under the cortex. This layer of peptidoglycan will become the cell wall of the bacterium after the endospore germinates
The inner membrane, under the germ cell wall, is a major permeability barrier against several potentially damaging chemicals. The center of the endospore,
the core
, exists in a very dehydrated state and houses
the cell's DNA
, ribosomes and large amounts of
dipicolinic acid
They are highly resistant forms of some
gram positive bacteria
formed in response to unfavourable conditions e.g : depletion of nutrients , hea . dryness , etc.
It is formed inside the vegetative cell so it is known as
endospores
.
once formed they have
no metabolic activity
and can remain dormant for years . On exposure to water and appropriate nutrients , specific enzymes degrades the coat and germination into bacterial cell occures
- The activities of the mother cell and forespore lead to the synthesis of the
endospore-specific compounds
, formation of the cortex and deposition of the coat (
Stages IV+V
).
-This is followed by the final dehydration and maturation of the endospore (
Stages VI+VII
)
-
Finally
, the mother cell is destroyed in
a

programmed cell death
, and the
endospore
is released into the environment . The endospore will remain dormant until it senses the return of more favorable conditions.
Full transcript