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BIOL 2259 - Microbio > Ch. 8 - Controlling Microbial Growth in Vitro > Flashcards

Ch. 8 - Controlling Microbial Growth in Vitro Flashcards

1
Q

Factors that affect microbial growth (6)

A
  • availability of nutrients
  • moisture
  • temperature
  • pH
  • osmotic pressure
  • barometric pressure
  • gaseous atmosphere
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2
Q

Optimum temperature/pH at which an organism functions is largely determined by ____

A

optimum temp/pH ranges of the enzymes

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3
Q

Thermophiles

A

microorganisms that grow best at higher temps

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4
Q

Mesophiles

A

microorganisms that grow best at moderate temps (37degrees)

- most likely the bacteria we see as pathogenic

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5
Q

Why does our body trigger a fever to fight infection?

A

High temp= low rate microbial growth because they are no longer at their ideal temperature for reproduction

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6
Q

Psychrophiles

A

Prefer cold temperatures

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7
Q

Psychrotrophs

A

group of psychrophiles that prefer fridge temperature

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8
Q

Psychroduric organisms

A

prefer warm temperatures but can endure cold to freezing

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9
Q

Acidophiles

A

prefer pH 2-5

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10
Q

Alkaliphiles

A

prefer pH greater than 8.5

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11
Q

DF Osmotic pressure

A

Pressure exerted on a cell membrane by solutions both inside and outside the cell

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12
Q

DF Osmossis

A

movement of a solvent through a permeable membrane from low solute concentration to high solute concentration

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13
Q

solvent vs solute

A

solvent: liquid
solute: the thing that dissolves in it

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14
Q

Hypertonic

A

concentration external solutes > concentration internal solutes

  • water rushes out of cell
  • cell shrinkage
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15
Q

Plasmolysis

A

Cell membrane and cytoplasm shrink away from the cell wall.

Occurs when bacteria with rigid cell walls are placed in hypertonic solution.

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16
Q

Crenation

A

Eukaryotic cell shrinking without cell wall, leading to weird cell shape
Occurs in hypertonic situations

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17
Q

Hypotonic

A

concentraion external solutes < concentration internal solutes

  • water rushes into cell
  • cell swelling/bursting
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18
Q

Plasmoptysis

A

process of cell bursting and cytoplasm escaping

- happens in hypotonic situations

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19
Q

Isotonic

A

concentration external solutes = concentration internal solutes

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20
Q

Explain IV fluids in regards to hypertonic/hypotonic concentrations

A

IV fluids are isotonic, meaning the concentration or solutes in the solution matches the concentration of solutes in your cells.
If IV bags were just water, we would be creating a hypotonic solution

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21
Q

Halophilic

A

prefer to live in salty environments

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22
Q

Haloduric

A

Do not prefer salty but could live there

ex: staphylococcus aureus

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23
Q

Piezophiles

A

microbes that can survive at high atmospheric pressures

> 14.7 PSI

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24
Q

Microaerophiles

A

prefer reduced O2 (~5%)

25
Q

Chemically defined media

A

All ingredients are known

26
Q

Enriched medium

A

contains special nutrients that promote growth of fastidious organisms
ex: chocolate agar

27
Q

Selective medium

A

contains added inhibitors that discourage the growth of certain organisms while allowed the growth of a desired organism
ex: PEA agar

28
Q

Differential medium

A

Permits the differentiation of organisms that grow on that medium.
We see colour changes depending on what kind of bacteria are there. As the bacteria grow, they lyse the cells of medium, leading to a release of colour
ex: MacConkey agar

29
Q

What type(s) of medium is blood agar?

A

enriched - allows certain bacteria to grow

differential - certain bacterial will lyse the medium cells leading to a colour change

30
Q

Aseptic technique

A

Using practices and procedures to prevent contamination from pathogens

31
Q

Biologic safety cabinets

A
  • Air flow that prevents any air binding bacteria from getting down to the agar. Minimize contamination and protect lab/person.
32
Q

Innoculation

A

Introducing microorganisms into a culture where they can grow and reproduce

33
Q

Incubation

A

the maintenance of microbiological cultures at specific temperatures for a given time.
Done using incubator which maintains appropriate atmosphere, temp, and moisture level

34
Q

3 Types of Incubators

A

1) CO2 incubator - 5-10% CO2
2) Non CO2 incubator - room air
3) Anaerobic incubator (0% O2)

35
Q

Spectrophotometer

A

Determines bacterial growth by measuring the turbidity (transparency) of the medium

36
Q

Viable Plate Count

A

Determines number of viable bacteria in liquid sample after making serial dilutions of the liquid and inoculating onto a nutrient agar. After overnight incubation, count the number of colonies

37
Q

2 Methods for bacterial population count

A

1) Spectrophotometer

2) Viable plate count

38
Q

Population growth curve

  • How is it determined?
  • (Y) vs (X) axis
A

Determined by growing a pure culture of the organism in a liquid medium at constant temp and collecting samples at fixed intervals
Graph: (Y) # viable organisms ; (X) incubation time

39
Q

Population growth curve: stages

A

Lag phase - bacteria adapt to growth conditions . Maturing and not yet able to divide

Log phase - exponential growth

Stationary phase - no growth, just using up resources

Death phase - Once resources are used up, number of cells die

40
Q

3 Obligate intracellular pathogens

A

viruses
Rickettsias
Chlamydias

These microbes can only live and multiply within living cells

41
Q

How do you culture obligate intracellular pathogens?

A

In embryonated chicken eggs, lab animals, or cell cultures

42
Q

Which agar is selective for fungi and why?

A

Sabouraud dextrose agar (SDA)

Selective for fungi because of its low pH , which is fungi like

43
Q

Sterilization

A

The complete destruction of all microbes, including cells, spores, and viruses.
Accomplished by dry heat, autoclaving, gas, radiation, chemicals

44
Q

Disinfection

A

Destruction/removal of pathogens from nonliving objects by physical or chemical methods

45
Q

Disinfectant vs antiseptic

A

disinfectant: chemical substances that eliminate pathogens on inanimate stuff
antiseptic: solutions used to disinfect skin and other living tissues

46
Q

Microbistatic agent

A

drug/chemical that inhibits growth and reproduction of microbes

47
Q

Lyophilization

A

Process combining dehydration and freezing.

Used to preserve foods, antibiotics, etc.

48
Q

Sepsis vs Asepsis

A

Sepsis: presence of pathogens in blood/tissues
Asepsis: absence of pathogens

49
Q

Antisepsis

A

prevention of infection

50
Q

Physical methods to Inhibit Microbial growth

A

1) Heat
2) Cold
3) Desiccation
4) Radiation
5) Ultrasonic waves
6) Filters
7) Gaseous atmosphere

51
Q

Thermal death point (TDP)

A

Lowest temperature that will kill all of the organisms in a standardized pure culture within a specified time

52
Q

Autoclave

A

large metal pressure cooker that uses steam under pressure to completely destroy all microbial life.
High pressure = high temperature >100degrees— forces steam into materials being sterilized

53
Q

How does cold temp affect microbial life?

A

Most microbials don’t die, but their metabolic activities are slowed

54
Q

How does desiccation affect microbial life?

A

Dries them out. Many remain viable, but they cant reproduce

55
Q

How does radiation affect microbial life?

A

reduces the number of microorganisms in the air

56
Q

What type of physical method is used on hospital equipment to inhibit microbial growth?

A

ultrasonic waves

57
Q

Chemical disinfection

A

use of chemical agents to inhibit the growth of pathogens, either temporarily or permanently

58
Q

Characteristics of an ideal chemical antimicrobial agent (3)

A

1) nontoxic to human tissue, non corrosive, no allergic reaction
2) Fast acting -kill pathogen before it mutates and becomes resistant
3) Should leave a residual antimicrobial film on surface to prevent further infection

59
Q

Asthma Cleanliness Hypothesis

A

Hypothesis: Childhood exposure to germs and certain infections help the immune system develop.
Our immune system is stimulated differently in a clean environment vs a farm etc.

BIOL 2259 - Microbio (11 decks)

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