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z - BIO103 - Microbiology > Lecture 4A - Culture Media, Biosafety, and Aseptic Technique > Flashcards

Lecture 4A - Culture Media, Biosafety, and Aseptic Technique Flashcards

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1
Q

is a nutrient-rich liquid or gel designed to support the growth of a target species or group of species

A

culture medium

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2
Q

culture medium is a ____ designed to support the growth of a target species or group of species

A

nutrient-rich liquid or gel

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3
Q

What ingredients do culture media typically contain

A
  • water
  • energy source
  • nitrogen source
  • mineral source
  • special growth factors
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4
Q

culture media: water

A

dissolve mix

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5
Q

culture media: energy source

A

usually a carbohydrate (glucose/dextrose)

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6
Q

culture media: nitrogen source

A
  • amino acids
  • protein sources (peptone)
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7
Q

culture media: mineral salts

A
  • MgSO4
  • NaCl
  • KH2PO4
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8
Q

simplest amino acid

A

glycine

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9
Q

Major components of a medium

A
  1. Hydrogen, carbon, nitrogen
  2. inorganic nutrients
  3. trace elements
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10
Q

hydrogen

A

donors and acceptors
~1-15 g/L

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11
Q

carbon

A

source
~1-20 g/L

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12
Q

nitrogen

A

source
~0.2 - 2 g/L

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13
Q

inorganic nutrients

A

Sulfur, Phosphorus
~50 mg/L

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14
Q

trace elements

A

0.1-1 µg/L

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15
Q

Additives of a medium

A
  1. growth factors
  2. solidifying agent
  3. solvent
  4. buffers
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16
Q

example of growth factors

A
  • amino acids
  • purines
  • pyrimidines
    (~50 mg/L)
  • vitamins
    (~0.1-1 mg/L)
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17
Q

example of solidifying agent

A

agar
(8-20 g/L)

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18
Q

percent of added standard agar

A

1.5-2%

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19
Q

percent of added high quality agar

A

1.5-1.7%

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20
Q
  • ensure that pH is maintained
  • very critical
A

buffers

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21
Q

Three types of culture media based on physical state

A
  1. solid medium
  2. semisolid medium
  3. liquid (broth) medium
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22
Q

for isolation of colonies which give distinct morphology on the surface of the medium

A

solid medium

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23
Q

percent of agar used in solid medium

A

1.5-2.0% or
1.5-2.0 g/100mL of medium

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24
Q

agar is a ___ __ __ prepared from seaweeds

A

golden-yellow granular powder

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25
Q

agar melts at

A

80°C

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26
Q

agar gels at

A

<40°C

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27
Q
  • soft custard-like consistency
  • prepared with agar at concentrations of 0.8% or less
  • useful for the cultivation of microaerophilic bacteria or for the determination of bacterial motility
A

semisolid medium

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28
Q

semisolid medium is useful for what?

A
  • cultivation of microaerophilic bacteria
  • determination of bacterial motility
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29
Q

percent of agar used in semisolid medium

A

0.8% or less

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30
Q
  • contain specific amounts of nutrients but do not contain solidifying agent
  • serves various purposes such as propagation of a large number of organisms, fermentation studies, and various other tests
A

liquid (broth) medium

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31
Q

various purposes of liquid (broth) medium

A
  • propagation of large number of organisms
  • fermentation studies
  • various other tests
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32
Q

examples of various other tests which uses liquid (broth) medium

A
  • sugar fermentation tests
  • MR-VR broth
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33
Q
  • organisms which can survive in both oxygenated as well as the deoxygenated environment
  • most adaptable organisms that have the capability to switch between aerobic and anaerobic types of respiration
A

Facultative anaerobe

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34
Q

Two types of culture media based on composition/ingredients

A
  1. complex
  2. defined/synthetic
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35
Q
  • with one or more unknown components
  • with complex ingredients
A

complex

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36
Q

example of complex ingredients

A
  • peptone
  • extracts
  • hydrolysates
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37
Q

example of rich medium

A
  • potato dextrose agar/broth
  • nutrient agar/broth
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38
Q

components of nutrient broth

A
  • beef extract (3.0 g)
  • peptone (5.0 g)
  • distilled water (1000mL)
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39
Q
  • proportion and identity of all components are known
  • pure chemical substances
  • may not be as rich as CM
A

defined/synthetic

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40
Q

example of defined/synthetic medium

A

Azotobacter enrichment medium

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41
Q

Types of culture media based on purpose

A
  1. general purpose media
  2. enrichment media
  3. selective media
  4. differential media
  5. transport media
  6. anaerobic media
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42
Q
  • support growth of many in a microbial group
  • do not contain any special additives
A

general purpose media

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43
Q

support growth of most cultivatable bacteria

A
  • nutrient agar (NA)
  • tryptic soy agar (TSA)
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44
Q

support growth of most cultivatable fungi

A

potato dextrose agar (PDA)

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45
Q

percent of microorganisms that have never been cultivated

A

99%

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46
Q
  • provide nutrients and conditions that favor the growth of a particular microbe
  • promotoe growth and dominance of a sensitive organism from a mixed culture
A

enrichment media

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47
Q

enriching medium to target microbial group with particular __ __

A

metabolic capacity

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48
Q

what makes an enriched medium

A

addition of extra nutrients to basal medium

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49
Q

what bacteria are grown in enriched media

A

fastidious bacteria

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50
Q

examples of enrichment media

A
  • blood agar
  • chocolate agar
  • Loeffler’s serum slope
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51
Q

blood agar

A

adding 5-10% blood to blood agar base

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52
Q

chocolate agar

A
  • heated blood agar
  • lysed blood agar
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53
Q

first used enrichment to study chemolithotrophy

A

Sergei Winogradsky

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54
Q
  • promote growth of organisms with the use of a favorable carbon source
  • reduce the growth of other organisms with the use of inhibitory substances
A

selective media

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55
Q

added to medium to eliminate unwanted microbes

A

inhibitory substance

56
Q

examples of inhibitory substances

A
  1. antibiotics
  2. dyes
  3. chemicals
  4. alteration of pH
57
Q

Type of medium of selective media

A

agar-based (solid)

58
Q

examples of selective media

A
  1. Sabouraud’s dextrose agar (SDA)
  2. Phenylethyl Alcohol Agar (PEA)
  3. Thayer Martin Medium
  4. Eosin Methylene Blue Agar (EMBA)
  5. Campylobacter Agar (CAMPY)
  6. Lowenstein-Jensen Medium
59
Q
  • high concentrations of sugar promote yeast growth and inhibit bacterial growth
  • low pH also inhibits bacteria
A

Sabouraud’s dextrose agar (SDA)

60
Q
  • promotes growth of Gram positive cocci
  • alcohol content tends to inhibit Gram-negative organisms
A

Phenylethyl Alcohol Agar (or Phenylethanol Agar) (PEA)

61
Q

pH level of Sabouraud’s dextrose agar (SDA)

A

pH 6

62
Q
  • coumarin-derived antibiotic obtained from Streptomyces niveus
  • antibacterial agent, an EC 5.99. 1.3 [DNA topoisomerase (ATP-hydrolysing)] inhibitor
  • antimicrobial agent, an Escherichia coli metabolite and a hepatoprotective agent
A

Novobiocin

63
Q

selective for Neisseria gonorrhoeae STD

A

Thayer Martin Medium

64
Q

combination of antibiotics in Thayer Martin medium

A
  1. vancomycin
  2. colistin
  3. nystatin
  4. trimethoprim
65
Q

Thayer Martin medium:
kill most Gram-positive organisms

A

vancomycin

66
Q

Thayer Martin medium:
kill most Gram-negative organisms except Neisseria

A

colistin

67
Q

Thayer Martin medium:
kill most fungi

A

Nystatin

68
Q

Thayer Martin medium:
inhibits Gram-negative organisms, esp. Proteus

A

Trimethoprim

69
Q
  • selective for Gram-negative bacteria
  • inhibit growth of Gram-positive bacteria
  • also contain dye eosin Y
A

Eosin methylene blue agar (EMBA)

70
Q

what inhibits growth of Gram-positive bacteria in eosin methylene blue agar (EMBA)

A

methylene blue

71
Q

what dye does eosin methylene blue agar (EMBA) also contain

A

eosin Y

72
Q

sugar in eosin methylene blue agar (EMBA)

A

sucrose
lactose

73
Q

bacteria isolated in eosin methylene blue agar (EMBA)

A

enterobacteriaceae

74
Q
  • isolation of Campylobacter jejuni from fecal or rectal swab
  • contain bacteriological charcoal, cefoperazone, and amphotericin B
A

Campylobacter Selective Agar (CAMPY)

75
Q

what is isolated in Campylobacter Selective Agar (CAMPY)

A

Campylobacter jejuni

76
Q

what does the Campylobacter Selective Agar (CAMPY) contain

A
  • bacteriological charcoal
  • Cefoperazone
  • Amphotericin B
77
Q

eosin methylene blue agar (EMBA):
what bacteria is possible to differentiate due to the presence of sugars lactose and sucrose

A

enteric bacteria

78
Q

Bacteria isolated in eosin methylene blue agar (EMBA)

A
  1. lactose-fermenting gram-negative bacteria
  2. slow lactose fermenters
  3. non-lactose fermenters
79
Q

lactose-fermenting gram-negative bacteria

A

green metallic sheen

80
Q

slow lactose fermenters

A

brown-pink colonies

81
Q

non-lactose fermenters

A

colorless or light pink colonies

82
Q
  • acidify lactose
  • vigorous lactose and/or sucrose fermentation ability typical of fecal coliforms
  • dark purple complex associated with green metallic sheen
A

lactose-fermenting gram-negative bacteria

83
Q

less acidify lactose

A

slow lactose fermenters

84
Q
  • increase pH
  • use sucrose in aerobic respiration
  • colorless/light pink colonies
  • eosin & methylene blue combine to form dark purple preciptate at low pH
A

non-lactos fermenters

85
Q

components of Campylobacter Blood Agar (CVA)

A
  1. peptones extracts
  2. yeast extract
  3. dextrose
  4. sheep blood
  5. antimicrobial agents
  6. agar
86
Q

Campylobacter Blood Agar (CVA):
supplies all the necessary growth factors

A

peptones extracts

87
Q

Campylobacter Blood Agar (CVA):
source of B vitamins

A

yeast extracts

88
Q

Campylobacter Blood Agar (CVA):
energy source

A

dextrose

89
Q

Campylobacter Blood Agar (CVA):
hemin and supplies other necessary additional growth factors

A

sheep blood

90
Q

Campylobacter Blood Agar (CVA):
- suppress the growth of the normal microbial flora in flecal speciments, therby facilitation isolation of C. jejuni
- cephalothin, polymycin B, trimethoprim, amphtericin B, and vancomycin

A

antimicrobial agents

91
Q

what are the antimicrobial agents in Campylobacter blood agar (CVA)

A
  1. cephalothin
  2. polymycin B
  3. trimethoprim
  4. amphotericin B
  5. vancomycin
92
Q

Campylobacter Blood Agar (CVA):
solidifiying agent

A

agar

93
Q
  • thermophiles
  • inoculated plates should be incubated at 42C to accelerate growth
  • higher temp. also inhibit background flora
A

Campylobacter jejuni

94
Q

temp. for accelerated growth of Campylobacter jejuni

A

42 C

95
Q
  • solid medium used for Mycobacterium tuberculosis
  • contain penicillin, nalidixic acid, and malachite green to inhibit growth of gram positive and gram negative bacteria, in order to limit growth to Mycobacteria species only
A

Lowenstein-Jensen Medium

96
Q

inhibit growth of Gram positive and Gram negative bacteria in Lowenstein-Jensen Medium

A
  1. penicillin
  2. nalidixic acid
  3. malachite green
97
Q
  • allow identification of microorganisms usually through the (visible) phsiological reactions unique to those bacteria
  • almost always selective
A

differential media

98
Q

most practical media are those that both what

A

select for and differentiate common pathogens

99
Q

differential media contain an __ that changes __ depending on the metabolites produced by the culture on the medium during incubation

A
  • indicator
  • color
100
Q

Examples of differential media

A
  1. Desoxycholate Agar
  2. MacConkey Medium
  3. Xylose Lysine Deoxycholate Agar (XLD)
  4. Urease Medium
  5. Thiosulfate-citrate-bile salts-sucrose agar (TCBS)
101
Q
  • recognize the presence of Gram-negative enteric bacteria that ferment the milk sugar lactose
  • these bacteria produce red pigment in the medium because of the acid it produce
A

Desoxycholate Agar

102
Q

pigment produced by Gram-negative enteric organisms in Desoxycholate Agar

A

red pigment

103
Q
  • differentiate lactose fermenters from non-lactose fermenters
  • only grows gram-negative bacterial species
  • can further differentiate the gram-negative organisms based on their lactose metabolism
A

MacConkey Medium

104
Q

components of MacConkey Medium

A
  1. Peptone
  2. Lactose
  3. Agar
  4. Neutral red
  5. Taurocholate
105
Q

used for the recovery of Salmonella and Shigella species

A

Xylose Lysine Deoxycholate Agar (XLD)

106
Q

Xylose Lysine Deoxycholate Agar (XLD):
- fermented by all enteric
- to enrich

A

xylose

107
Q

Xylose Lysine Deoxycholate Agar (XLD):
- enable Salmonella to differentiate with nonpathogens
- attached by lysine decarboxylase

A

lysine

108
Q

Xylose Lysine Deoxycholate Agar (XLD):
generates acid products when degraded causing color change to medium

A

xylose
lactose
sucrose

109
Q

added to visualize hydrogen sulfide

A
  • sodium thiosulfate
  • ferric ammonium citrate
110
Q

Xylose Lysine Deoxycholate Agar (XLD):
hydrogen sulfide

A

black (neutral/pH alkaline)

111
Q

Xylose Lysine Deoxycholate Agar (XLD):
pH scale below 7

A

From phenol red to yellow

112
Q
  • tests the ability of an organism to produce an exoenzyme, called urease, that hydrolyzes urea to ammonia and carbon dioxide
  • contains two pH buffers, urea, a very small amount of nutrients for the bacteria, and the pH indicator phenol red
A

Urease Medium

113
Q

Urease Medium:
presence of urease (basic)

A

pink

114
Q
  • highly selective for the isolation of Vibrio cholerae
    and V. parahaemolyticus
  • very alkaline (8.5-9.5)
A

Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

115
Q

carbon source of Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

A

sucrose

116
Q

dye differentiation in Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

A
  • bromothymol blue
  • thymol blue
117
Q

what does light blue indicate in Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

A

V. parahaemolyticus

118
Q

pH level of Thiosulfate-citrate-bile salts-sucrose agar (TCBS)

A

8.5 - 9.5

119
Q
  • media used for transporting samples
  • non nutritional (non growing)
  • isotonic
A

transport media

120
Q

transport media can maintain __ of micoorganisms without __

A
  • viability
  • multiplication
121
Q

what does transport media prevent

A

oxidizing and drying

122
Q

components of transport media

A
  1. sodium thioglycolate
  2. sodium glycerophosphate
  3. saline (calcium chloride)
  4. methylene blue
123
Q

Transport media:
sequester oxygen

A

sodium thioglycolate

124
Q

Transport media:
oxygen diffusor
colorless (if without oxygen)

A

methylene blue

125
Q

Transport media:
permeability

A

saline (calcium chloride)

126
Q

Transport media:
maintain pH

A

sodium glycerophosphate

127
Q

used to grow anaerobic organisms

A

anaerobic media

128
Q

Examples of anaerobic media

A
  1. Robertson’s cooked meat medium
  2. Thioglycolate broth medium
129
Q
  • nutrient broth with meat pieces
  • meat pieces create small packets of anaerobic habitats
A

Robertson’s cooked meat medium

130
Q
  • used for testing oxygen requirement of bacteria
  • contains resazurin (will turn pink due to presence of oxygen)
A

Thioglycolate broth medium

131
Q

medium will turn pink due to presence of oxygen

A

indicator resazurin

132
Q

Concept Check:
culture media can be manipulated to target the growth and isolation of specific microorganisms

A

true

133
Q

Concept Check:
enrichment media can be used to allow particular growth of microbes to dominate culture

A

true

134
Q

Concept Check:
indicators are used to differentiate species growin on differential media

A

true

135
Q

Concept Check:
PDA - bacteria
NA - fungi

A

false

136
Q

Concept Check:
all microbes are cultivatable

A

false

z - BIO103 - Microbiology (18 decks)

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