Lecture 16-17 Culture media, Cultivation techniques, & Types of cultures Flashcards

1
Q

Two broad classes of culture media

A

chemically defined and complex

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2
Q

Chemically defined

A

exact composition of pure chemicals used to formulate medium is known

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3
Q

Used for well characterized isolates in lab studies

A

chemically defined

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4
Q

Complex media (“rich” media)

A

exact chemical composition is poorly defined

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5
Q

Used as a non-specific medium for growing many organisms

A

rich media

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6
Q

Often naturally sourced components

A

rich media

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7
Q

Selective media

A

inhibits growth of unwanted organisms, supports growth of desired organisms

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8
Q

The dye that inhibits growth of Gram-positives and selects for the isolation of Gram-negatives

A

Brilliant Green (BG) agar

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9
Q

Enriched media

A

contains growth factors, vitamins, and other essential nutrients to promote the growth of fastidious organisms

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10
Q

Fastidious organisms

A

organisms that cannot make certain nutrients and require them to be added to their medium

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11
Q

Commonly used to supply nutrients in various mediums

A

blood, serum, egg yolk

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12
Q

Used to grow a wide range of pathogens, particularly those that are more difficult to grow

A

enriched media

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13
Q

Differential media

A

contains compounds that allow groups of microorganisms to be visually distinguished by the appearance of the colony or the surrounding media

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14
Q

What basis does differential media use to show visual differences?

A

biochemical differences

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15
Q

Alpha hemolysis

A

indistinct zone of partial destruction

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16
Q

Beta hemolysis

A

clear, colorless zone appears

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17
Q

Gamme hemolysis

A

no apparent hemolytic activity or discoloration

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18
Q

Examples of selective AND differential media

A

MacConkey Agar & Mannitol Salt Agar

19
Q

MacConkey Agar

A

inhibit Gram-positives (w/ bile salts and crystal violet) and produces a color change (w/ lactose fermenters)

20
Q

Mannitol Salt Agar

A

mannitol fermentation and phenol red for differentiation, high salt selects of S. aureus (only super hardy and high salt loving will grow)

21
Q

Colony

A

a visible mass of microbial cells arising from one cell or from a group of the same microbes

22
Q

Batch cultures

A

closed system, nutrients not renewed, exponential growth limited to a few generations

23
Q

Continuous (chemosat) cultures

A

bacterial cultures maintained in a state of exponential growth over long periods of time

24
Q

Culturing technique that allows for bacterial population at a constant density

A

continuous cultures

25
Q

What continuous culturing relieves

A

nutrient insufficiency, accumulation of waste products, and accumulation of cells

26
Q

Steps to making an aerobic culture

A

1) make culture media
2) sterilize medium
3) inoculate liquid or steak plate
4) incubate in aerobic environment until culture grows

27
Q

Used for anaerobic culturing when microbe can be mildly exposed to H2O

A

GasPak Jar or Anaerobic GasPak container

28
Q

Used for anaerobic culturing when microbe CANNOT be exposed to H2O

A

Anaerobic chamber/glove box; very delicate

29
Q

Contains only one species or strain

A

pure culture

30
Q

Colony

A

a population of cells arising from a single cell or spore or from a group of attached cells

31
Q

Another name for a colony

A

colony-forming unit (CFU)

32
Q

Method used to isolate pure cultures

A

streak plate method

33
Q

Describe the streak plate method

A

small amount of inoculum is picked up on a sterile inoculating loop, drawn repeatedly across the surface of the plate

34
Q

Biofilms

A

microbial communities

35
Q

Where do you find biofilms?

A

in slime or hydrogel environments

36
Q

Communication in biofilms

A

quorum sensing

37
Q

What quorum sensing allows for

A

allows bacteria to coordinate activity and group together into communities

38
Q

Benefits of biofilms

A

share nutrients, sheltered from harmful factors, responsible for many chronic infections and diseases

39
Q

Percentage of infections that are caused by biofilms

A

70%

40
Q

What do Biosafety Levels do (BSLs)

A

describes the condition of the lab

41
Q

BSL 1

A

for nonpathogenic microbes, PPE required, standard sterile conditions

42
Q

BSL 2

A

for pathogens not readily transmitted by aerosol/contact, same day decontamination of all biological materials

43
Q

BSL 3

A

for pathogens transferred by aerosol/contact and pose a serious health threat, water in only, protective lab clothing required, non-circulating airflow

44
Q

BSL 4

A

for readily-transmitted (highly contagious) pathogens causing fatal diseases with no preventative vaccine or cure, full-body air-supplied “space suit”, facility located in separate building