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Microbiology > Lab Quiz #2 > Flashcards

Lab Quiz #2 Flashcards

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1
Q

Batch culture

A

Closed culture vessel with a single batch of medium

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2
Q

Growth curve: x and y axes

A

X: incubation time
Y: logarithm of viable cells

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3
Q

4 phases of growth curve

A

Lag phase
Exponential (log) phase
Stationary phase
Death phase

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4
Q

Lag phase

A

No immediate increase in cell number

Microbes adjust to new environment and synthesize cellular components necessary for growth

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5
Q

Exponential (log) phase

A

Growth of microbes is constant

Population doubles at regular intervals

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6
Q

What value is calculated during exponential (log) phase and what does it measure?

A

Generation time (time required for microbial population to double in size)

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7
Q

Stationary phase

A

Growth of population ceases (no net increase or decrease in cell number)
Due to depletion of nutrients and accumulation of toxic waste products

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8
Q

During stationary phase, what type of metabolites are produced? Bacteria that can do so form what dormant structures?

A 
Secondary metabolites (antibiotics, etc.)
Spores
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9
Q

Death phase

A

Number of viable cells decreases at exponential rate

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10
Q

How direct count is calculated using Petroff-Hausser counting chamber

A

Number of cells in given area x volume of chamber (area x depth) x dilution factor

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11
Q

How a standard curve is constructed

A

2 fold-dilutions of culture of known concentration

Cell concentration plotted against optical density

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12
Q

Determination of viable vs inviable cells using standard curve and viable count procedure

A

Compare standard curve to OD readings in viable cell count: if concentration of cells at a particular OD from viable counting matches the concentration of cells at the same OD from standard curve, can assume that only viable cells are being counted

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13
Q

In viable counting, what method is used to obtain cells of a concentration low enough for plating?

A

Serial dilution (successive 10 fold dilutions- 10 microliters in 900 microliters diluent)

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14
Q

How cell concentration/CFUs is calculated in viable counting

A

(Average # of colonies counted x dilution factor)/ volume plated

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15
Q

Bacteria show variation in what 3 areas?

A

Morphology, metabolism, physiology

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16
Q

Myxobacteria: Gram negative or positive? Environment? What makes them different from other bacteria in terms of how they interact with others of the same species and different species?

A

Gram negative
Soil
Social bacteria (maintain close contact with other Myxobacterial cells)
Prey upon other bacteria

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17
Q

Gliding motility: what type of bacteria? Are flagella involved? What does it allow these bacteria to do? What is formed from their movement?

A

Myxobacteria
Flagella-independent
Enables swarming on surfaces in an organized manner
Form ripples on solid surface

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18
Q

Example genera of Myxobacteria that has a unique life cycle

A

Myxococcus xanthus

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19
Q

Upon starvation, Myxococcus xanthus aggregate to form what? A subpopulation of cells differentiates into what? What are 2 traits of this differentiated cell type?

A

Fruiting bodies
Myxospores
Dormant, stress resistant

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20
Q

Myxospores can be contained in sacs called what?

A

Sporangioles

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21
Q

When transferred to fresh medium, myxospores can do what?

A

Germinate, giving rise once again to vegetative cells

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22
Q

Actinomycetes: what type of respiration, Gram positive or negative, act as intermediates between what 2 microorganism types and why

A

Aerobic respiration
Gram positive
Intermediate between bacteria and fungi: form branching filaments like fungi

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23
Q

2 types of mycelia formed by Actinomycetes and their features

A

Vegetative (grow into media)

Aerial (powdery appearance, produced by conidiospores)

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24
Q

Example genera of Actinomycetes

A

Streptomyces

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25
Q

Odor of most soil is due to production of what by what type of bacteria?

A

Geosmin

Streptomyces

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26
Q

Streptomyces produce compounds that are major sources of what?

A

Antibiotics

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27
Q

Purpose of photosynthesis

A

Capture light energy and convert it to chemical energy

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28
Q

Over half of photosynthesis on earth is carried out by what?

A

Microorganisms

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29
Q

2 types of photosynthetic microbes: differences between them (2)

A

Cyanobacteria: oxygenic photosynthesis, chlorophylls as light-gathering pigments
Green and purple bacteria: anoxygenic photosynthesis, bacteriochlorophylls as light-gathering pigments

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30
Q

Difference between oxygenic and anoxygenic photosynthesis

A

Oxygenic: water as electron source, production of oxygen
Anoxygenic: other reduced compounds as source of electrons, no oxygen produced

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31
Q

2 accessory pigments used by photosynthetic bacteria

A

Carotenoids

Phycobiliproteins

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32
Q

3 purposes of accessory pigments

A

Absorb light of different wavelengths than major pigments
Transfer light energy gathered to major pigments
Protect microorganisms from intense, damaging sunlight

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33
Q

Green sulfur and purple sulfur bacteria use sulfur how?

A

Metabolism of inorganic sulfur compounds in photosynthesis

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34
Q

Purple nonsulfur bacteria: what type of compound replaces sulfur in photosynthesis?

A

Organic compound

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35
Q

Green and purple sulfur bacteria: what relationship to oxygen?

A

Obligate anaerobes (cannot tolerate oxygen)

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36
Q

Purple nonsulfur bacteria: what relationship to oxygen?

A

Facultative anaerobes (don’t require oxygen for growth, but grow better in its presence)

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37
Q

Example of purple nonsulfur bacterium viewed in lab

A

Rhodospirillum rubrum

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38
Q

Example genus of Cyanobacteria

A

Anabaena

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39
Q

Under nitrogen limiting conditions, Anabaena will differentiate into what type of cells? What do these cells do and what is their size relative to other cells?

A

Heterocysts
Nitrogen fixation
Larger than other cells

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40
Q

Winogradsky column used in lab resembles what type of habitat?

A

Fairly deep stagnant lake

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41
Q

Ingredients of Winogradsky column (6)

A 
Mud from lake, etc.
Calcium sulfate (CaSO4)
Calcium carbonate (CaCO3)
Cellulose
Egg yolk
Water
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42
Q

3 initial layers of Winogradsky column

A

Mud with additives
Mud with no additives
Water

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43
Q

5 columns created: growth conditions, ingredients

A
  1. All ingredients, light source
  2. All ingredients, no light source
  3. No CaSO4, CaCO3, cellulose, or egg yolk; light source
  4. No CaCO3 or cellulose; light source
  5. No CaCO3 or egg yolk; light source
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44
Q

CaSO4 and egg yolk serve as source of what for Winogradsky column?

A

Sulfur

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45
Q

Cellulose and CaCO3 serve as source of what for Winogradsky column?

A

Carbon

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46
Q

Initially, entire Winogradsky column is ______.

A

Anaerobic

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47
Q

First event that occurs in Winogradsky column

A

Heterotrophic microorganisms oxidize some of the organic matter and consume O2, making lower parts of column anaerobic

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48
Q

Reaction scheme of Winogradsky column first event

A

Organic matter + O2 -> Organic acids + CO2

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49
Q

Second event that occurs in Winogradsky column

A

Organic acids act as electron donors for reduction of sulfates and sulfites to hydrogen sulfide (H2S) by anaerobic sulfate-reducing bacteria

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50
Q

Reaction scheme of Winogradsky column second event

A

Organic acids + SO4 -> H2S-CO2

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51
Q

Third event that occurs in Winogradsky column

A

Photosynthetic organisms such as purple and green sulfur bacteria use H2S as electron donor to reduce CO2 directly into carbohydrates for use by bacteria

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52
Q

Genera of purple and green sulfur bacteria (2)

A

Chromatium

Chlorobium

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53
Q

Reaction scheme of Winogradsky column third event

A

CO2 + H2S + light -> carbohydrate + S

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54
Q

Fourth event that occurs in Winogradsky column

A

Once H2S level is reduced, purple non-sulfur bacteria (photosynthetic) appear
Purple non-sulfur bacteria use low levels of H2S as electron donor to reduce CO2 into carbohydrates

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55
Q

Reaction scheme of Winogradsky column fourth event

A

CO2 + H2S + light -> carbohydrate + S

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56
Q

Final Winogradsky column: microorganism composition, oxygen concentration in each layer, which layer is which

A

Protozoans, fungi, algae, aerobic bacteria, anaerobic bacteria
Anaerobic (bottom, mud), aerobic (top, aqueous)

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57
Q

In what layer are protozoans, fungi, algae, and aerobic bacteria found? In what layer are photosynthetic bacteria found?

A

Aerobic layer: protozoans, fungi, algae, aerobic bacteria

Anaerobic layer: photosynthetic bacteria

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58
Q

Exception to four events of Winogradsky column in terms of purple non-sulfur bacteria

A

Early on, purple non-sulfur bacteria appear in upper portion of Winogradsky column (rust color)
At that point in time, purple non-sulfur bacteria use organic matter instead of H2S as electron donor

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59
Q

What type of bacteria grow throughout the Winogradsky column?

A

Heterotrophic bacteria

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60
Q

What type of microorganisms grow towards the top of the Winogradsky column?

A

Algae

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61
Q

Cyanobacteria grow in between what other 2 types of microorganisms in Winogradsky column?

A

Algae (above), colorless sulfur-oxidizing bacteria (below)

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62
Q

Colorless sulfur-oxidizing bacteria grow in between what other 2 types of microorganisms in Winogradsky column?

A

Cyanobacteria (above)

Purple non-sulfur bacteria (below)

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63
Q

Purple non-sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?

A

Colorless sulfur-oxidizing bacteria (above)

Purple sulfur bacteria (below)

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64
Q

Purple sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?

A

Purple non-sulfur bacteria

Green sulfur bacteria

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65
Q

Green sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?

A

Purple sulfur bacteria

Anaerobic bacteria

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66
Q

What type microorganisms grow towards the bottom of the Winogradsky column?

A

Anaerobic bacteria

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67
Q

Repressive selection

A

Choosing growth conditions that repress the growth of interfering microbes while at the same time permitting growth of the culture sought

68
Q

Enrichment selection

A

Choosing growth conditions that encourage the growth of the sought-after microbe so it will out-compete its competitors

69
Q

Differential plating

A

Using indicators to make it easier to recognize the sought-after species without the use of inhibitors or enrichment

70
Q

Escherichia coli: habitat, Gram negative or positive, shape

A

Lower intestinal tract
Gram negative
Rod

71
Q

Is E. coli motile or non-motile? Does it form spores? Does it ferment acid?

A

Motile
No spores
Mixed acid fermentation

72
Q

Differential media

A

Used to distinguish between groups of microbes

73
Q

Enterococcus faecalis: habitat, Gram negative or positive, shape

A

Lower intestinal tract
Gram positive
Cocci

74
Q

Is E. faecalis motile or non-motile? Does it form spores?

A

Non-motile

No spores

75
Q

Staphylococcus: habitat, Gram negative or positive, shape

A

Mammalian skin
Gram positive
Cocci

76
Q

Is Staphylococcus motile? Does it form spores? What type of hemolytic activity does it display?

A

Non-motile
No spores
Can be beta or gamma hemolytic

77
Q

Bacillus: habitat, Gram negative or positive, shape

A

Soil
Gram positive
Rod

78
Q

Is Bacillus motile? Does it form spores?

A

Motile

Forms spores

79
Q

Pseudomonas: habitat, Gram negative or positive, shape

A

Soil
Gram negative
Rod

80
Q

Is Pseudomonas motile? Does it form spores?

A

Motile

No spores

81
Q

2 pigments produced by Pseudomonas: names, colors, function, UV fluorescence or not

A

Pyoverdin: yellow-green, fluoresces under UV light, functions as siderophore (iron uptake)
Pyocyanin: blue-green, doesn’t fluoresce under UV light

82
Q

Pseudomonas aeruginosa and Psuedomonas fluorescens: pyoverdin, pyocyanin, or both?

A

Pseudomonas aeruginosa: both

Pseudomonas fluorescens: pyoverdin only

83
Q

Azotobacter: habitat, Gram negative or positive, shape

A

Soil
Gram negative
Large, ovoid-rod shape

84
Q

Is Azotobacter motile? Does it form spores? What is a special feature of this bacteria?

A

Can be motile or non-motile
No spores
Able to fix N2

85
Q

When growing on N2 as a nitrogen source, Azotobacter produce what for what purpose?

A

Extensive polysaccharide capsules

Protect nitrogenase

86
Q

When media becomes deficient in nutrients, Azotobacter may produce what?

A

Cysts (large, ovoid resting structures that are resistant to dessication)

87
Q

TTC deep: TTC stands for what?

A

Triphenyl tetrazolium chloride

88
Q

How is the TTC deep selective?

A

Obligate aerobes cannot grow in it (stab inoculation shoves bacteria into deep)

89
Q

How is the TTC deep differential?

A

Differentiates motile from non-motile organisms: motile organisms produce red/pink color throughout deep

90
Q

Why is color change seen in TTC deep?

A

TTC accepts electrons from bacterial oxidations and is reduced

91
Q

E. coli and S. aureus: motile or non-motile?

A

E. coli: motile

S. aureus: non-motile

92
Q

TSI slant: TSI stands for what? What 3 types of sugars does it contain?

A

Triple sugar iron agar

Lactose, glucose, sucrose

93
Q

Is the TSI slant selective, differential, or both?

A

Non-selective
Differential: distinguishes enteric bacteria based on fermentation ability of different sugars, production of gas, and production of H2S

94
Q

TSI slant contains what pH indicator?

A

Phenol red

95
Q

What 2 parts of TSI slant are observed?

A

Butt (stab inoculation)

Slant (streak incoluation)

96
Q

Acid vs alkaline test of TSI slant: colors, what they indicate

A

Red: alkaline, no fermentation
Yellow: acid, fermentation

97
Q

K/K vs K/A vs A/A in TSI slant: what color of butt vs slant, what is indicated

A

K/K: alkaline slant and butt; non-fermenter
K/A: alkaline slant, acid butt; glucose fermentation only
A/A: acid slant and butt; glucose, sucrose, and/or lactose fermentation

98
Q

TSI slant: gas production is indicated by what?

A

Cracked agar at bottom, bubbles

99
Q

TSI slant: H2S production is indicated by what? H2S reacts with what media component?

A

Black color

Ferrous sulfate

100
Q

TSI results for E. coli

A

A/A (yellow slant and butt; fermentation of glucose, sucrose, and/or lactose)
Gas produced
No H2S

101
Q

Tryptone broth: selective or differential?

A

Non-selective or differential

102
Q

Ingredients of indole production test

A 
Tryptone broth
Kovacs reagent (contains aldehyde)
103
Q

Indole production test is used to differentiate between what types of bacteria?

A

Those that can produce indole (E. coli) from those that can’t (other enterics such as Proteus, Pseudomonas)

104
Q

Indole production test reaction

A

Tryptophan -> indole + ammonia + pyruvic acid

105
Q

Indole production test colors and what they mean

A

Red: indole +
Yellow: indole -

106
Q

Bile esculin broth: selective, differential, or both

A

Selective and differential

107
Q

Selectivity of bile esculin broth

A

Selective: bile salts inhibit Streptococcus

108
Q

Differentiation of bile esculin broth

A

Tests ability to hydrolyze esculin to glucose and esculetin (black complex)

109
Q

E. faecalis: bile esculin broth results

A

Black color produced: can grow and produces esculetin

110
Q

MacConkey agar: selective, differential, or both

A

Selective and differential

111
Q

Selectivity of MacConkey agar

A

Crystal violet inhibits gram + bacteria, so gram - bacteria are selected

112
Q

Differentiation of MacConkey agar

A

Lactose with neutral red dye in media: lactose fermentors appear pink, non-fermentors such as Salmonella appear colorless to yellow

113
Q

E. coli: MacConkey agar results

A

Growth, pink color due to lactose fermentation

114
Q

Ashby’s nitrogen free agar: selective, differential, or both

A

Selective, non-differential

115
Q

Selectivity of Ashby’s nitrogen free agar

A

Microorganisms that fix atmospheric nitrogen grow

116
Q

Azotobacter: Ashby’s nitrogen free agar results

A

Growth: can fix N2

117
Q

Tryptic soy agar (TSA) and Luria Bertani: selective, differential, both, or neither

A

Non-selective, non-differential

118
Q

CNA stands for what? What is an active ingredient of it?

A

Colistin-Nalidixic acid

Contains blood

119
Q

CNA: selective, differential, or both

A

Selective and differential

120
Q

Selectivity of CNA

A

Gram + bacteria grow: colistin disrupts lipids and LPS in gram - outer membrane

121
Q

Bacillus are gram positive, so do they grow on CNA?

A

Most strains don’t grow on CNA

122
Q

Differentiation of CNA

A

Blood enables detection of hemolytic activity

123
Q

What are the 3 types of hemolytic activity, and how are they detected?

A

Alpha: partial lysis of RBCs, green color
Beta: complete lysis of RBCs, transparent color
Gamma: no lysis of RBCs, no change in agar

124
Q

Pseudomonas enrichment benzoate medium: Pseudomonas can convert ______ in medium to _____ and _____, which can be used in the _____ _____.

A

Hydroxybenzoate
Acetyl-CoA
Succinate
TCA cycle

125
Q

PAF plate: PAF stands for what?

A

Pseudomonas agar F

126
Q

PAP plate: PAP stands for what?

A

Pseudomonas agar P

127
Q

PAF and PAP plates: selective, differential, or both?

A

Non-selective

Differential

128
Q

Differentiation of PAF plate

A

Color change is produced for pyoverdin

129
Q

What color does P. aeruginosa produce on PAF plate? What color does P. fluorescens produce on PAF plate?

A

P. aeruginosa: green

P. fluorescens: yellow

130
Q

Differentiation of PAP plate

A

Color change is produced for pyocyanin

131
Q

What species of Pseudomonas produces pyocyanin? What color is pyocyanin?

A

P. aeruginosa

Blue

132
Q

Mannitol salt agar: selective, differential, or both?

A

Selective and differential

133
Q

Selectivity of mannitol salt agar

A

High salt concentration inhibits all growth except Staphylococcus

134
Q

Differentiation of mannitol salt agar

A

Mannitol fermentors turn agar yellow (acid formation)

135
Q

Mannitol salt agar results for S. aureus and S. epidermidis

A

S. aureus: yellow

S. epidermidis: red (no change)

136
Q

Blood agar: selective, differential, or both?

A

Differential

137
Q

Differentiation of blood agar

A

Blood enables detection of hemolytic activity

138
Q

Beta hemolysis: 3 organisms

A

E. coli
S. aureus
Streptococcus pyogenes

139
Q

Alpha hemolysis: organism

A

Streptococcus pneumoniae

140
Q

Gamma hemolysis: 2 organisms

A

Staphylococcus epidermidis

Enterococcus

141
Q

DNase test agar: 2 possible indicators

A

Toluidine blue

Methyl green

142
Q

DNase: selective, differential, or both?

A

Selective and differential

143
Q

Selectivity of DNase

A

Methyl green inhibits some gram positive organisms

144
Q

Differentiation of DNase

A

Reveals DNase activity
DNase positive: clear zone (methyl green) or violet zone (toluidine blue) caused by DNA hydrolysis
DNase negative: no change in agar

145
Q

2 DNase positive organisms and 2 DNase negative organisms

A

DNase positive: Serratia, S. aureus

DNase negative: Enterobacter, S. epidermidis, E. coli

146
Q

Oxidase test determines presence of what enzyme? What metabolic process is this enzyme involved in?

A

Cytochrome oxidase

Involved in electron transport

147
Q

How oxidase test works: name of indicator, what is done to it, what is final result

A

Indicator: tetramethylphenylenediamine dihydrochloride
Oxidized
Production of purple color

148
Q

2 oxidase positive organisms

A

Azotobacter

Pseudomonas

149
Q

4 oxidase negative organisms

A

Escherichia, Staphylococcus, Enterococcus, Streptococcus

150
Q

What organisms can be either oxidase positive or negative?

A

Bacillus

Azotobacter

151
Q

Catalase test: how does it work? Ingredient? Reaction? Final result?

A

Hydrogen peroxide detects presence of catalase
H2O2 -> H2O + O2
Bubbles formed: positive test

152
Q

Catalase test can be used to differentiate members of what 2 genera?

A

Staphylococcus: positive
Streptococcus: negative

153
Q

2 organisms that are catalase negative

A

Streptococcus

Enterococcus

154
Q

Biofilms

A

Multicellular, surface-attached communities

155
Q

Are biofilms always made up of members of the same species, or can there be multiple species present?

A

Can be either

156
Q

Where do biofilms form in aquatic habitats (3)? What can they form on in the human body (2)?

A

Rocks
Water lines
Hulls of ships
Catheters, implants of hip and knee

157
Q

3 stages of biofilm development

A

Attachment
Colonization
Development

158
Q

Attachment stage of biofilm development

A

Individual bacteria transition from planktonic (free-living) cells to adherent surface attached cells

159
Q

What 2 types of cell-wall associated structures assist in attachment of bacteria in a biofilm?

A

Pili

Fimbriae

160
Q

Colonization stage of biofilm development

A

Attached cells begin synthesizing and releasing polysaccharides, proteins, and DNA, forming protective matrix

161
Q

Matrix formed during colonization of biofilm serves what 2 functions?

A

Trap nutrients

Protection from harmful agents (antibiotics, host immune response)

162
Q

Development stage of biofilm formation

A

Mushroom-like colonies of bacteria are formed

Contain channels through which nutrients flow and feed biofilm

163
Q

Quorum sensing: what is it, what stages of biofilm development is it associated with

A

Communication between bacteria by sending and receiving chemical signals
Both colonization and development stages

164
Q

How biofilm formation was measured in lab

A

Optical density: higher OD value, greater biofilm-forming ability

165
Q

3 species of bacteria used in biofilm experiment: names, which was best biofilm former

A

E. coli, S. epidermidis, P. fluorescens

Best biofilm former: P. fluorescens

166
Q

Which temperature, 30 or 37 degrees Celsius, was more favorable to biofilm formation?

A

37 degrees Celsius

Microbiology (24 decks)

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