L3 Two sides of bacterial endospores Flashcards
What are the two main genus names tend to form endospores
bacillus
clostridium
what type of bacteria form endospores (not genus)
gram positive rods
how long does it take for a cell to make an endospore?
8 hours
when do cells produce endospores
when the cell is subject to significant stress
as a last resort effort
what are the three options for a cell when it is subjected to significant stress
die
enter dormancy
form endospores
once conditions are optimal how long does it take for an endospore to germinate
15 minutes
steps of endospore creation
the vegetative cell begins to divide by binary fission
DNA becomes denser and septum forms asymmetrically
larger compartment (mother cell) engulfs the smaller compartment (forespore)
the peptidoglycan enclosing the forespore forms the cortex
the mother cell makes proteins that forms the coat
the mother cell degrades (lysis)
what are the 7 layers of the endospore
core inner membrane germ cell wall cortex outer membrane coat exosporium
what does the actual core contain
metabolically inactive DNA and ribosomes
what three layers are in the core group of endospores
core
inner membrane
germ cell wall
what does the second functional group of the endospore contain
cortex
outer membrane
what is the cortex made up of
less crosslinked peptidoglycan
what is the 3rd functional layer of the endospores
coat
what is the coat and purpose
surrounds the cortex
composed of many protein layers
can be very thick and is impermeable (chemical and UV resistance)
what is the 4th functional layer of an endospore
exosporium
what is an exosporium and purpose
thin outer layer
lipid carbohydrate and protein
overall coat to the endospore
what 2 attributes groups determines endospore resistance
physical
chemical
what physical factors contribute to endospore resistance
coat (thick layers) inner membrane (impermable)
what chemical factors determine endospore resistance
CORE low water content lower pH high content of dipicolinic acid and Ca2+ small acid-soluble proteins
CORTEX
decreased peptidoglycan cross-linking (2.9%)
what is the water content of an endospore
15%
how does a high conc of dipicolinic acid and Ca2+ contribute to resistance
the Ca2+ link to the dipiclonic acid and DNA forming lattice structure
what do small acid-soluble proteins do?
these bind to DNA and alter the conformation of DNA which protects it from damage
how does having a lower peptidoglycan cross-linking in the cortex help resistance?
required for spore coat dehydration, metabolic dormancy and heat resistance
compare the peptidoglycan of vegetative cells with endospores
33% in vege
2.9% in endo
what are the three phases of endospore germination
activation
germination
outgrowth
what does activation involve
preparing the endospore for germination
what does the germination phase involve
endospore swells up, rupturing the spore coat
loss of resistance, modified peptidoglycan is involved
what does outgrowth involve
spore emerges from remains of coat and develops into vegetative cells
microbe of the day
bacillus subtilis
bacillus subtilis type, niche, use in sterilisation
gram-positive rod
naturally found in soil and the gut of ruminants and humans
can survive very stressful environments
used to indicate efficacy of sterilisation
definition of the results of physical control methods
death sterilisation disinfection antisepsis bactericidal (kill) bacteriostatic (inhibits)
two types of heat as a physical control method
moist heat
dry heat
types of moist heat
autoclave
boiling water
pasteurisation
what temperature, time must an autoclave meet
121 degrees
15 minutes
what temperature does bioling water get to
100 degrees
so does not kill endospores
two types of pasteurisation
batch
flash
what does batch pasteurisation involve
low temp long time
63 degrees 30 mins
what does flash pasteurisation involve
high temp short time
71 degrees
15 seconds
two types of dry heat
flaming/ incineration
hot air oven
