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Microbiology > Biofilms > Flashcards

Biofilms Flashcards

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Biology 101 flashcards
1
Q

where do biofilms grow

A

interfaces

solid: liquid, solid:air, liquid:air, liquid:liquid

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2
Q

biofilms aren’t bound to and growing at an interface TF

A

FALSE

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3
Q

When do biofilms form

A

when MOs attach to surfaces and grow

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4
Q

do biofilms bring about any phenotypic change?

A

yes immediate phenotype change- resistance

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5
Q

what is the road of glycocalyx (slime). how soon does this form

A

forms within minutes

moderates the physio-chemical environment of the MO- anything that wants to get to them has to pass through the slime

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6
Q

what charged substances can get through a biofilm? why

A

positive

as a biofilm tends to be negative

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7
Q

biofilms lead to ________ formation. ____ cell density

A

micro colony

high

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8
Q

can a biofilm only contain one species

A

yes, many hospital infections are single species

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9
Q

what type of MOs can be found in biofilms?

A 
bac
yeast 
algae 
fungi 
protozoa
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10
Q

what is the primary organism in biofilms?

A

bacteria

then get further tertiary colonisers

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11
Q

biofilms provide protection from what?

A

dessication- hydrated layer

phagocytes

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12
Q

why are biofilms good for the microorganisms nutrient wise?

A

concentrates them

concentrates extracellular products- one species breakdown things which can be used by other species

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13
Q

how can biofilms aid resistance

A

interspecies genetics- transfer of resistance genes due to being in close proximity

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14
Q

how do we treat indwelling device infection with biofilm?

A

another surgery and replacement of the implant is the only way

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15
Q

does a biofilm cover a whole surface?

A

no can be patchy

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16
Q

if a biofilm forms on the inside of a pipe what happens to the flow capacity

A

decreases- similar situation in arteries

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17
Q

3 examples of biofilms associated with indwelling devices?

A

pacemakers
CNS shunts
catheters

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18
Q

do we know why biofilms are so resistant?

A

not 100% sure

we have 3 theories

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19
Q

what are the 3 theories of why biofilms are so resistant?

A

exclusion
cell-cell signalling
biofilm cells- concentrations

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20
Q

explain the theory of exclusion influencing resistance

A

AM agents cant penetrate the biofilm as easily (can still penetrate)

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21
Q

explain the theory of biofilm cells- concentrations influencing resistance

A

cells on the edge of the biofilm might get killed by an agent but not the ones deeper down
nutrient gradients- deeper in the biofilm there’s less so the bacteria grow slower- this makes them more resistant

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22
Q

how does slower metabolism effect resistance?

A

makes them more resistance as they grow slower

can be due to being deeper in the biofilm therefore less access to nutrients

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23
Q

explain how the cell-cell signalling theory can contribute to resistance?

A

cells communicate when in high cell density (biofilms) using low MW diffusible materials
allows them to up-regulate genes using HSLs

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24
Q

what do cells in a biofilm use communicate

A

low MW diffusible materials

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25
Q

what are HSLs?

A

homoserine lactones

26
Q

what produces HSLs?

A

almost all gram negative bacteria

27
Q

what are the effects of HSLs building up in a biofilm?

A

once a threshold concentration is reached, this up regulates genes in the producing organisms: AUTOINDUCTION

28
Q

what is alloinduction

A

when the HSLs produced by one type of organism, up regulates genes in an unrelated species

29
Q

what is auto induction

A

HSL production causes upregulation of genes in the producing organism

30
Q

what is the threshold HSL concentration for gene upregulation

A

depends on the producing organism

31
Q

what is quorum sensing?

A

population responds on mass - coordinated population response

32
Q

what is quorum sensing key in?

A

biofilm resistance to AM agents

33
Q

6 steps in biofilm formation

A
  1. arrival at surface
  2. irreversible attachment to surface
  3. adoption of sessile phenotype
  4. biosynthesis of exopolymers
  5. upregulation in the production of virulence factors
  6. detachment and dispersal
34
Q

what would the cells in the biofilm do if they run out of food?

A

they would leave and seek a new surface to colonise

35
Q

3 mechanisms a bacterial cell approaches the surface?

A

diffusion
motility chemotaxis
turbulence

36
Q

what type of bacteria does diffusion occur in when approaching a surface?
process is _____

A

non motile bacterium

random

37
Q

explain motility chemotaxis

A

chemotaxis response

smell glucose on a surface and move towards the nutrients

38
Q

what forces hold a bacteria to the surface in reversible binding?

A

VDW

electrostatic forces

39
Q

what must the bacteria do if they want to irreversibly bind to the surface?

A

overcome energy barrier

40
Q

what would aid a bacteria to overcome the energy barrier and attach to a surface irreversibly?

A

projections- the narrower the easier it is to overcome the barrier

narrower organism

41
Q

what are projections called in the process of irreversible attachment to surface?

A

bridging structures- helps them, overcome the barrier

42
Q

what occurs after irreversible binding?

A

exopolysmer deposition and phenotypic switch

43
Q

what effect does ‘exopolysmer deposition’ have

A

re-inforces binding

modulates the environment

44
Q

what leads to micro colony formation?

A

growth and multiplication

45
Q

what are micro colonies?

A

small pockets of cells

46
Q

3 types of biofilm phenotypes?

A

corncobs
mushroom
plaque like

47
Q

explain how a corncob biofilm grows

A

thin and upwards quite dramatically

48
Q

explain how a mushroom biofilm grows?

A

water flows around the biofilm causing it to be top heavy

49
Q

what environments are mushroom biofilms found

A

aq

50
Q

what are plaque like biofilms like

A

a thick mass of cells

51
Q

how can plaque turn into a mushroom

A

increasing turbulence of flow across the population

52
Q

biofilms are ____genou

A

heterogenous

53
Q

what must you stop to stop succession of biofilms?

A

the primary colonisers

e.g. higher organisms cannot colonise if the primary colonisers aren’t present

54
Q

3 mechanisms of biofilm dispersal

A

enzymatic sloughing
physical sloughing by shear force
erosion- cell cycle mediated

55
Q

why would cells want to disperse?

A

surface gets deprived of nutrients

56
Q

when does enzymatic sloughing occur and how?

A

under starvation mechanism

production of lyase enzymes which breakdown exopolysaccharides (slime) so chunks of cells can be removed

57
Q

enzymatic sloughing is _____.

continuous or periodic

A

periodic

58
Q

how does physical sloughing work in regards to dispersal of biofilm

A

shear force

cells are washed away

59
Q

physical sloughing is difficult to ______

A

regulate

60
Q

explain cell cycle mediated

A

events in the cell cycle- erosion events where one cell is released

61
Q

why is cell cycle mediated dispersal from biofilm easy to detect?

A

happened one at a time

happens continuously

Microbiology (19 decks)

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