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PRIS > Bacterial physiology > Flashcards

Bacterial physiology Flashcards

1
Q

How does bacterial growth occur?

A
  • asexual replication
  • occurs by binary fission
  • single bacteria divide to produce two daughter cells
  • bacteria population double in each replication round
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2
Q

One bacteria can generate many = source of infection - how fast can fast growth bacteria replicate?

A
  • every 10-15 minutes
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3
Q

Describe the steps in binary fission?

A
  1. cell replicates its entire DNA - including plasmids
  2. the cytoplasmic membrane elongates separating DNA molecules
  3. DNA molecules separate into individual entities and move towards poles
  4. cross wall forms, membrane invaginates
    5/ cross wall forms completely
  5. daughter cells are formed
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4
Q

What does growth by binary fission mean for cell mass?

A
  • means cell mass doubles each generation
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5
Q

What can bacterial growth time be measured in?

A
  • generation time
  • population doubling time
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6
Q

How quickly does E.coli double?

A
  • every 20 minutes
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7
Q

How quickly does M.bovis double?

A
  • every 20-24hrs
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8
Q

How often does M. leprae double?

A
  • every 20 days!!
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9
Q

What affect does bacteria doubling time have?

A
  • has an impact in treatment and culturing methods
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10
Q

What are the minimum nutritional requirements for bacteria?

A
  • water
  • carbon source to generate proteins and ATP
  • nitrogen source
  • inorganic salts
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11
Q

What can autotrophs do?

A
  • synthesise own organic compounds
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12
Q

What can heterotrophs not do?

A
  • cannot synthesise own organic compounds
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13
Q

Some heterotrophs are pathogenic - what are some examples?

A
  • Pseudomonas spp.
  • Klebsiella spp.
  • Escherichia spp.
  • Salmonella spp.
  • Campylobacter spp.
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14
Q

What have heterotrophs evolved to do?

A
  • host-pathogen co-evolution (reliance) = leads itself to infectious disease
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15
Q

What are autotrophs’ typically?

A
  • non-pathogenic
  • clostridium difficile
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16
Q

What can labs use to cultivate bacteria?

A
  • liquid media and solid media (agar)
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17
Q

Not all bacteria will grow on the same media - what may we need to supplement them with?

A
  • blood products
  • salts to cultivate bacteria outside of host
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18
Q

What is the general temperature bacteria need to grow?

A
  • 37 degrees
  • species differences as they grow at body temp of host
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19
Q

What can we do to identify and determine antibiotic resistance profiles and what can this help with?

A
  • isolation
  • helps apply correct treatment
20
Q

What bacteria require complex media?

A
  • pathogenic and clinically relevant ones
21
Q

How can you collect bacteria?

A
  • swabs
  • tissue samples
22
Q

What is MIDGET?

A
  • dye in media that gives off a signal as soon as bacteria begins to divide
  • such as colour change
23
Q

How can we measure antibiotic resistance?

A
  • clinical isolates are screen against antibiotics
  • bacteria spread in plate
  • paper disks soaked in antibiotics laid on top
  • bacteria allowed to grow
  • measure zones of clearance
24
Q

What does it mean if there are clearance zones with no bacterial growth?

A
  • sensitive to antibiotics
25
Q

What does it means if there is no clearance zone an bacterial growth?

A
  • resistant to antibiotics
26
Q

What’s the optimal growth temperature range for thermophiles?

A
  • 50-80’c
27
Q

What’s the optimal growth temperature range for Mesophiles?

A
  • 20-45’C
28
Q

What’s the optimal growth temperature range for Psychotrophs?

A
  • 4-25’C
29
Q

What’s the optimal growth temperature range for psychophiles?

A
  • 0-15’C
30
Q

Some bacteria are capable of growth between wide ranges - name an example?

A
  • Listeria monocytogenes – optimal growth range 30-37°C
  • Capable of growth between 1-45°!!
31
Q

Clinical isolates are typically cultured at what pH?

A
  • neutral
32
Q

How can you classify organisms by pH?

A
  • Neutrophilic organisms
    E.g., E. coli, S. aureus, Salmonella spp. - pathogenic ones
  • Acidophilic organisms
    e.g., Lactobacillus spp.
  • Alkalophilic organisms
    e.g., Vibrio spp.
33
Q

How do microaerophile use o2?

A
  • use O2 but only at very low cons
34
Q

How do obligate aerobes use O2?

A
  • require 02 and cant survive without it
35
Q

How do obligate anaerobes use O2?

A
  • unable to use O2 and cant survive if its present
36
Q

How do facultative aerobes use O2?

A
  • use 02 but can can survive without it
37
Q

How do aerotolerant anaerobes use O2?

A
  • don’t use O2 but can grow in its presence
38
Q

How do bacteria grow in liquid?

A
  • in a defined manner
39
Q

What does measurements over intervals create?

A
  • growth curve
40
Q

What are the 4 stages of bacterial growth?

A
  • lag
  • log
  • stationary
  • decline
41
Q

What happens during the lag phase?

A
  • bacteria increase in size
  • small numbers of doubling
42
Q

What is the logarithmic stage?

A
  • bacteria start dividing or doubling
  • exponential increase in bacterial numbers
43
Q

What is the stationary phase?

A
  • bacterial division ceases
  • depletion of nutrients
  • build up of toxic products
  • can produce antimicrobial to control communities around them
  • in solids some bacteria change colour due to stress
44
Q

What is the decline phase?

A
  • actively start lysin = dying
    – no more nutrients and toxic build up products
    – see clarification of culture
45
Q

What is bacterial physiology important for?

A
  • Important for identification of bacteria
    -Understanding nutritional requirements
  • useful for pathological niche, environmental survival
  • Control of clinically relevant bacteria
  • Antibiotic resistance
  • Reducing spread

PRIS (16 decks)

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