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Microbial Growth Flashcards

1
Q

Essential nutrients for bacterial growth

A
  • C, H, O, N, P ,S
  • Protein function: Mg, Ca, Fe, K
  • Enzyme function: Co, Cu, Mn, Zn
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2
Q

What liquid media used for?

A
  • Profuse growth

- Unseparated mixed organisms

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3
Q

What solid media used for?

A
  • Identifying bacteria by studying colony characteristics and separated mixed organisms
  • Pure isolation culture
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4
Q

What basic media used for?

A
  • Support most non-fastidious bacteria
  • Primary isolation for microorganism
  • Ex: nutrient agar
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5
Q

What enriched medium used for?

A
  • Add extra nutrients
  • Grow fastidious bacteria
  • Ex: blood agar
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6
Q

What selective media used for?

A
  • Inhibit unwanted bacteria
  • Include additional of antibiotic, dye, chemicals, and pH
  • Ex: PEA, Mannitol salt
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7
Q

What differential/indicator medium used for?

A
  • Include dye and specific nutrient
  • Allow more than one microorganism with different morphology
  • Ex: EMB, McConkey, citrate
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8
Q

Direct measurement

A
  • Standard plate counts
  • Microscopic count
  • Filtration
  • Coulter counter
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9
Q

Indirect measurement

A
  • Turbidity
  • Metabolic activity
  • Dry weight
  • Genetic probing
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10
Q

Facts abt standard plate counts

A
  • Most common
  • Dilute to get individual
  • Countable colonies
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11
Q

When to use filtration?

A

Small number of microbes

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12
Q

How to filtration?

A
  • Water run through filter

- Filter applied toTSA plate and incubated

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13
Q

Facts abt tubidity

A
  • More bacteria, more cloudiness

- Measure absorbance and transmission with spectrophotometer or eye

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14
Q

How to metabolic activity?

A

Assume amount of metabolic product is proportional to number

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15
Q

When to use dry weight?

A

Filamentous organisms

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16
Q

What is genetic probing?

A

Real-time PCR

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17
Q

When is TNTC and TFTC in standard plate count?

A

TNTC > 300

TFTC < 25

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18
Q

Bacterial growth curve

A
  • log: number of cells or absorbance

- Time: record every 30 minutes

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19
Q

Bacterial growth curve

Lap phase

A

when cell starts activate the metabolism but adapting to new environment and not actively replicated

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20
Q

Bacterial growth curve

Log/ exponential phase

A

Result of cell division

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21
Q

Bacterial growth curve

Stationary phase

A

The rate of cell death = the rate of cell division

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22
Q

Bacterial growth curve

Death/ decline phase

A

The rate of cell death

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23
Q

Continuous culture

A

Cell growing in the media where you constantly reapply fresh nutrition

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24
Q

When to use continuous culture

A

Want to keep to culture in log phase to maximum the production

25
Chemostat
Continuous culture device that maintains cell populations in exponential growth for long periods
26
How chemostat work?
Constantly add and remove equal amount of culture media
27
Bacterial growth curve in continuous culture | Steady state
Same to stationary phase but actively replicating to new cell production high
28
Bacterial growth curve in continuous culture | Doubling time
- Estimate how quickly bacteria replicate | - Decrease doubling time to speed up metabolism
29
Chemotaxis
Bacteria move towards nutrient and attractants and away from toxins
30
How filament drive?
By proton motive force
31
How flagella move CCW?
Attractants cause - Flagella bundle together. - Push cell forward - Run
32
How flagella move CW?
Repellents cause - Bundle falls apart - Bacterium briefly stop - Change direction
33
Facilitated diffusion
Carrier molecule carry solute and put them into cytoplasma
34
Active transport
Molecule move from low concentration to high concentration by ATP or prolomotive force
35
Group translocation
Chemical modified
36
Symport coupled transport system
2 molecules travel same direction
37
Antiport coupled transport system
Molecule actively travel different direction to driving ion
38
ABC transporters
Universal proteins use ATP to deliver
39
Nutrient uptake
- Permeases: substrate-specific carrier proteins - Nutrient-binding proteins: patrol the periplasmic space - Protein channels/pores: membrane-spanning
40
Importer ABC transporters
Mediate hydrophilic substrates into cell (only prokaryote)
41
Exporter ABC transporters
Pump toxin out of cell
42
Key elements of ABC transporters
- Substrate-specific binding protein - Trans-membrane domain - Nucleotide-binding domain
43
How ABC transporter work?
1. Resting state: NBD held open by TMDs and face outward from cytoplasm 2. Outward facing: SSBP go into periplasmic side of TMD, ATP bind and make NBD close 3. Inward facing: after release Pi, binding protein leave; TMD and NBD open to release substrate to cytoplasm 4. After releasing ADP, back to resting state
44
What PTS system do?
Transport carbohydrates into cell
45
How PTS system work?
1. PEP donate phosphate group to E1 and turn into pyruvate. E1 donate that group to HPr. HPr donate to E2a. E2a donate to E2b. 2. E2b donate to E2c with with glucose in membrane 3. Glucose transport into cell
46
Factors of microbial growth
``` Nutrient Temperature pH Oxygen Pressure Osmolarity ```
47
Temperature classification
Psychrophiles: 0-20oC Mesophiles: 15-45oC Thermophiles: 40-80oC Hyperthermophiles: 65-121oC
48
Heat-shock proteins
Chaperones Proteases Enzymes
49
Chaperones
maintain other protein's shape
50
Proteases
break down unfixable protein
51
Enzyme
change membrane lipid composition
52
How heat-shock response work?
1. At normal temperature, rpoH is transcribed; mRNA secondary structure hide ribosome-binding site; little sigma32 made 2. DnaK-DnaJ-GrpE push little sigma32 into degradation 3. At high temp, mRNA secondary structure melt; ribosome-binding site expose; sigma32 made 4. Sigma32 recruit RNA to go to gene and regulate it 5. Chaperones refold unfolded native protein while heat-shock gene break down other unfolded protein
53
Barophile
Grow at very hgh pressure
54
Barotolerant
Grow just well but die after that
55
Aquaborin
Membrane-channel proteins allow water to move into the cell faster than by diffusion
56
Barosensitive
Die when pressure high
57
Hypertonic media minimize osmotic stress
Synthesis or import compatible solutes
58
Hypotonic media minimize osmotic stress
Use mechanosensitive channels to leak solutes out of the cell
59
Halophile
Require high salt concentration

Microbiology (8 decks)

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