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Physiology of Microbes > Bacterial Endospores L16 > Flashcards

Bacterial Endospores L16 Flashcards

1
Q

what are endospores

A

dormant structures formed by bacterial cells in unfavourable environments

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2
Q

where are endospores

A

only in gram positive genera

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3
Q

where are endospores usually found

A

mostly in bacillus and clostridium

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4
Q

where can endospores also be found that is not common

A

Can also be formed in less common genera of bacteria

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5
Q

what are the gram negative bacteria (purple)

A

Escherichia coli
Salmonella typhimurium
Agrobacterium tumefaciens
Campylobacter jejuni

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6
Q

what are the gram positive bacteria

A

Bacillus anthracis
Clostridium botulinum
Staphylococcus aureus
Listeria monocytogenes

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7
Q

which of the gram positive bacteria that are spore forming

A

Bacillus anthracis

Clostridium botulinum

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8
Q

who discovered spores

A

ferdinand cohn

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9
Q

what did ferdinand cohn demonstrate

A

heat-resistant properties of endospores in Bacillus subtilis

showed the vegetative cells but not the endospores are killed in boiling water

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10
Q

what did ferdinand cohns discovery lead to

A

development of the autoclave

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11
Q

what do spore forming bacteria aid

A

identification process
Spore is always in the same place if same cell
restricted to small amount of bacteria – spore forming
Phenomenum in all of them is different

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12
Q

how are endospores formed

A

intracellularly

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13
Q

what does sporulation start with

A

asymmetric division of the mother cell

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14
Q

where do spore layers develop

A

inside mother cell

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15
Q

what happens in sporulation

A

released from mother cell / sporangium as free spores

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16
Q

what happens in sporulation process

A

1.asymmetric cell division, spore septum begins to isolate newly replicated DNA and small portion of cytoplasm septum forms at one end of the cell – not cell in half
2. Plasma membrane starts to surround DNA cytoplasm and membrane isolated
End up with a small cell and a big cell – two separate compartments
3. Second engulfment of the spore by the remaining cell
Programmed cell death to form the sporangium
4. Makes peptidoglycan between the two membranes that have formed in the cell
5. DNA degrades, coat forms around peptidoglycan layer, further protection
6. Endospore released

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17
Q

what are endospore composed of

A 
central spore surrounded by various protective layers
exosporium
spore coat
cortex
core
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18
Q

what is the exosporium

A

thin covering made of protein

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19
Q

what is spore coat

A

highly cross-linked keratin and layers of spore specific proteins

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20
Q

what is the cortex

A

loosely cross-linked peptidoglycan

21
Q

what is the core

A

condensed chromosome, packaging proteins and spore-specific compounds

22
Q

if there is severe dehydration what happens

A

no processes can occur

23
Q

what are bacterial endospores known for

A

most heat resistant living structures

24
Q

what are bacterial endospores resistant to

A 
Pressure
Vaccum
Desiccation
Irradiation (UV, X- and γ- rays)
Antibiotics
Chemical disinfectants
Extremes of pH
Heat
25
Q

what are the reasons for spore stability

A 
Proteinaceous Coat 
Calcium dipicolinate 
Specialized DNA-binding proteins 
Dehydration of the cortex 
DNA repair enzymes in the endospore
26
Q

what is the proteinaceous coat function in spore stability

A

resists lysozyme /degradative enzymes; impermeability of this layer protects spore from chemical inactivation

27
Q

what is the calcium dipicolinate function in spore stability

A

stabilises DNA

28
Q

what is specialised DNA-binding proteins function in spore stability

A

coats DNA and protects from heat, drying, chemicals, UV radiation

29
Q

what is dehydration of cortex function in spore stability

A

removes water from endospore interior and prevents diffusion

30
Q

what is the DNA repair enzymes in endospore function in spore stability

A

repair damaged DNA during germination

31
Q

what can spores used for

A

some spores contain spore associated toxins

clostridium botulinum causes botulism - for botox, causes paralysis of muscles

32
Q

what can spores cause in humans

A

Bacillus cereus & Clostridium perfringens cause food poisoning (GI tract)*

33
Q

what is bacillus thuringiensis protein specific for

A

Lepidoptera

34
Q

what must the conditions be for bacillus thuringiensis be to be solubilised

A

only solubilised under alkaline conditions (in gut of insect larvae) activated in alkali (insect gut pH is alkali)

35
Q

what is bacillus thuringiensis purified toxin known as

A

organic pesticide

36
Q

how can purified toxin be made

A

can purify the toxin then use that

Or can spray around bacillus thuringeiensis the organism that makes the toxin (natural so preferred)

37
Q

what is the downside of the natural method to produce purified toxin

A

closely related to bacillus cereus which will do that to us to harmful

38
Q

how can endospores enter the body

A

abrasions to skin orin lungs

39
Q

what happens when spores enter the body

A

favourable conditions allow the spores germinate and new vegetative cells start to grow

40
Q

what is a bacterial endospore

A

a neurotoxin

41
Q

what causes sporulation

A

Entry into the sporulation cycle can only occur at a specific point in the cell cycle
Requires active cell division
dont want togo into sporulation unless have to

42
Q

what things lead to sporulation

A

nutritional signals

population density

43
Q

how do nutritional signals lead to sporulation

A

Carbon, Nitrogen or Phosphorous starvation induce sporulation
Rapidly metabolised carbon sources, (e.g. glucose) repress sporulation

44
Q

how does population density lead to sporulation

A

Sporulation not induced efficiently at a low population density
At high density vegetative cells grown produce a substance necessary for efficient sporulation

45
Q

what do some endospores need before germination

A

activation

46
Q

how are most endospores activated

A

heat - required for optimum germination but amount of heat varies with spore type
or chemical signal - some simple chemical act as signals

47
Q

what is a downside of sporulation

A

very energy costly - Cells don’t induce this unless appropriate environmental signals present

48
Q

what is an advantage of endospores

A

can persist for a long time in inert state

49
Q

what is a disadvantage of germination

A

not guaranteed - dependent on environmental signals

Physiology of Microbes (21 decks)

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