Lab Quiz #2 Flashcards
1
Q
Batch culture
A
Closed culture vessel with a single batch of medium
2
Q
Growth curve: x and y axes
A
X: incubation time
Y: logarithm of viable cells
3
Q
4 phases of growth curve
A
Lag phase
Exponential (log) phase
Stationary phase
Death phase
4
Q
Lag phase
A
No immediate increase in cell number
Microbes adjust to new environment and synthesize cellular components necessary for growth
5
Q
Exponential (log) phase
A
Growth of microbes is constant
Population doubles at regular intervals
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)
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
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
9
Q
Death phase
A
Number of viable cells decreases at exponential rate
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
11
Q
How a standard curve is constructed
A
2 fold-dilutions of culture of known concentration
Cell concentration plotted against optical density
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
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)
14
Q
How cell concentration/CFUs is calculated in viable counting
A
(Average # of colonies counted x dilution factor)/ volume plated
15
Q
Bacteria show variation in what 3 areas?
A
Morphology, metabolism, physiology
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
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
18
Q
Example genera of Myxobacteria that has a unique life cycle
A
Myxococcus xanthus
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
20
Q
Myxospores can be contained in sacs called what?
A
Sporangioles
21
Q
When transferred to fresh medium, myxospores can do what?
A
Germinate, giving rise once again to vegetative cells
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
23
Q
2 types of mycelia formed by Actinomycetes and their features
A
Vegetative (grow into media)
Aerial (powdery appearance, produced by conidiospores)
24
Q
Example genera of Actinomycetes
A
Streptomyces
25
Odor of most soil is due to production of what by what type of bacteria?
Geosmin
| Streptomyces
26
Streptomyces produce compounds that are major sources of what?
Antibiotics
27
Purpose of photosynthesis
Capture light energy and convert it to chemical energy
28
Over half of photosynthesis on earth is carried out by what?
Microorganisms
29
2 types of photosynthetic microbes: differences between them (2)
Cyanobacteria: oxygenic photosynthesis, chlorophylls as light-gathering pigments
Green and purple bacteria: anoxygenic photosynthesis, bacteriochlorophylls as light-gathering pigments
30
Difference between oxygenic and anoxygenic photosynthesis
Oxygenic: water as electron source, production of oxygen
Anoxygenic: other reduced compounds as source of electrons, no oxygen produced
31
2 accessory pigments used by photosynthetic bacteria
Carotenoids
| Phycobiliproteins
32
3 purposes of accessory pigments
Absorb light of different wavelengths than major pigments
Transfer light energy gathered to major pigments
Protect microorganisms from intense, damaging sunlight
33
Green sulfur and purple sulfur bacteria use sulfur how?
Metabolism of inorganic sulfur compounds in photosynthesis
34
Purple nonsulfur bacteria: what type of compound replaces sulfur in photosynthesis?
Organic compound
35
Green and purple sulfur bacteria: what relationship to oxygen?
Obligate anaerobes (cannot tolerate oxygen)
36
Purple nonsulfur bacteria: what relationship to oxygen?
Facultative anaerobes (don't require oxygen for growth, but grow better in its presence)
37
Example of purple nonsulfur bacterium viewed in lab
Rhodospirillum rubrum
38
Example genus of Cyanobacteria
Anabaena
39
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?
Heterocysts
Nitrogen fixation
Larger than other cells
40
Winogradsky column used in lab resembles what type of habitat?
Fairly deep stagnant lake
41
Ingredients of Winogradsky column (6)
```
Mud from lake, etc.
Calcium sulfate (CaSO4)
Calcium carbonate (CaCO3)
Cellulose
Egg yolk
Water
```
42
3 initial layers of Winogradsky column
Mud with additives
Mud with no additives
Water
43
5 columns created: growth conditions, ingredients
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
44
CaSO4 and egg yolk serve as source of what for Winogradsky column?
Sulfur
45
Cellulose and CaCO3 serve as source of what for Winogradsky column?
Carbon
46
Initially, entire Winogradsky column is ______.
Anaerobic
47
First event that occurs in Winogradsky column
Heterotrophic microorganisms oxidize some of the organic matter and consume O2, making lower parts of column anaerobic
48
Reaction scheme of Winogradsky column first event
Organic matter + O2 -> Organic acids + CO2
49
Second event that occurs in Winogradsky column
Organic acids act as electron donors for reduction of sulfates and sulfites to hydrogen sulfide (H2S) by anaerobic sulfate-reducing bacteria
50
Reaction scheme of Winogradsky column second event
Organic acids + SO4 -> H2S-CO2
51
Third event that occurs in Winogradsky column
Photosynthetic organisms such as purple and green sulfur bacteria use H2S as electron donor to reduce CO2 directly into carbohydrates for use by bacteria
52
Genera of purple and green sulfur bacteria (2)
Chromatium
| Chlorobium
53
Reaction scheme of Winogradsky column third event
CO2 + H2S + light -> carbohydrate + S
54
Fourth event that occurs in Winogradsky column
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
55
Reaction scheme of Winogradsky column fourth event
CO2 + H2S + light -> carbohydrate + S
56
Final Winogradsky column: microorganism composition, oxygen concentration in each layer, which layer is which
Protozoans, fungi, algae, aerobic bacteria, anaerobic bacteria
Anaerobic (bottom, mud), aerobic (top, aqueous)
57
In what layer are protozoans, fungi, algae, and aerobic bacteria found? In what layer are photosynthetic bacteria found?
Aerobic layer: protozoans, fungi, algae, aerobic bacteria
| Anaerobic layer: photosynthetic bacteria
58
Exception to four events of Winogradsky column in terms of purple non-sulfur bacteria
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
59
What type of bacteria grow throughout the Winogradsky column?
Heterotrophic bacteria
60
What type of microorganisms grow towards the top of the Winogradsky column?
Algae
61
Cyanobacteria grow in between what other 2 types of microorganisms in Winogradsky column?
Algae (above), colorless sulfur-oxidizing bacteria (below)
62
Colorless sulfur-oxidizing bacteria grow in between what other 2 types of microorganisms in Winogradsky column?
Cyanobacteria (above)
| Purple non-sulfur bacteria (below)
63
Purple non-sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?
Colorless sulfur-oxidizing bacteria (above)
| Purple sulfur bacteria (below)
64
Purple sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?
Purple non-sulfur bacteria
| Green sulfur bacteria
65
Green sulfur bacteria grow in between what other 2 types of microorganisms in Winogradsky column?
Purple sulfur bacteria
| Anaerobic bacteria
66
What type microorganisms grow towards the bottom of the Winogradsky column?
Anaerobic bacteria
67
Repressive selection
Choosing growth conditions that repress the growth of interfering microbes while at the same time permitting growth of the culture sought
68
Enrichment selection
Choosing growth conditions that encourage the growth of the sought-after microbe so it will out-compete its competitors
69
Differential plating
Using indicators to make it easier to recognize the sought-after species without the use of inhibitors or enrichment
70
Escherichia coli: habitat, Gram negative or positive, shape
Lower intestinal tract
Gram negative
Rod
71
Is E. coli motile or non-motile? Does it form spores? Does it ferment acid?
Motile
No spores
Mixed acid fermentation
72
Differential media
Used to distinguish between groups of microbes
73
Enterococcus faecalis: habitat, Gram negative or positive, shape
Lower intestinal tract
Gram positive
Cocci
74
Is E. faecalis motile or non-motile? Does it form spores?
Non-motile
| No spores
75
Staphylococcus: habitat, Gram negative or positive, shape
Mammalian skin
Gram positive
Cocci
76
Is Staphylococcus motile? Does it form spores? What type of hemolytic activity does it display?
Non-motile
No spores
Can be beta or gamma hemolytic
77
Bacillus: habitat, Gram negative or positive, shape
Soil
Gram positive
Rod
78
Is Bacillus motile? Does it form spores?
Motile
| Forms spores
79
Pseudomonas: habitat, Gram negative or positive, shape
Soil
Gram negative
Rod
80
Is Pseudomonas motile? Does it form spores?
Motile
| No spores
81
2 pigments produced by Pseudomonas: names, colors, function, UV fluorescence or not
Pyoverdin: yellow-green, fluoresces under UV light, functions as siderophore (iron uptake)
Pyocyanin: blue-green, doesn't fluoresce under UV light
82
Pseudomonas aeruginosa and Psuedomonas fluorescens: pyoverdin, pyocyanin, or both?
Pseudomonas aeruginosa: both
| Pseudomonas fluorescens: pyoverdin only
83
Azotobacter: habitat, Gram negative or positive, shape
Soil
Gram negative
Large, ovoid-rod shape
84
Is Azotobacter motile? Does it form spores? What is a special feature of this bacteria?
Can be motile or non-motile
No spores
Able to fix N2
85
When growing on N2 as a nitrogen source, Azotobacter produce what for what purpose?
Extensive polysaccharide capsules
| Protect nitrogenase
86
When media becomes deficient in nutrients, Azotobacter may produce what?
Cysts (large, ovoid resting structures that are resistant to dessication)
87
TTC deep: TTC stands for what?
Triphenyl tetrazolium chloride
88
How is the TTC deep selective?
Obligate aerobes cannot grow in it (stab inoculation shoves bacteria into deep)
89
How is the TTC deep differential?
Differentiates motile from non-motile organisms: motile organisms produce red/pink color throughout deep
90
Why is color change seen in TTC deep?
TTC accepts electrons from bacterial oxidations and is reduced
91
E. coli and S. aureus: motile or non-motile?
E. coli: motile
| S. aureus: non-motile
92
TSI slant: TSI stands for what? What 3 types of sugars does it contain?
Triple sugar iron agar
| Lactose, glucose, sucrose
93
Is the TSI slant selective, differential, or both?
Non-selective
Differential: distinguishes enteric bacteria based on fermentation ability of different sugars, production of gas, and production of H2S
94
TSI slant contains what pH indicator?
Phenol red
95
What 2 parts of TSI slant are observed?
Butt (stab inoculation)
| Slant (streak incoluation)
96
Acid vs alkaline test of TSI slant: colors, what they indicate
Red: alkaline, no fermentation
Yellow: acid, fermentation
97
K/K vs K/A vs A/A in TSI slant: what color of butt vs slant, what is indicated
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
TSI slant: gas production is indicated by what?
Cracked agar at bottom, bubbles
99
TSI slant: H2S production is indicated by what? H2S reacts with what media component?
Black color
| Ferrous sulfate
100
TSI results for E. coli
A/A (yellow slant and butt; fermentation of glucose, sucrose, and/or lactose)
Gas produced
No H2S
101
Tryptone broth: selective or differential?
Non-selective or differential
102
Ingredients of indole production test
```
Tryptone broth
Kovacs reagent (contains aldehyde)
```
103
Indole production test is used to differentiate between what types of bacteria?
Those that can produce indole (E. coli) from those that can't (other enterics such as Proteus, Pseudomonas)
104
Indole production test reaction
Tryptophan -> indole + ammonia + pyruvic acid
105
Indole production test colors and what they mean
Red: indole +
Yellow: indole -
106
Bile esculin broth: selective, differential, or both
Selective and differential
107
Selectivity of bile esculin broth
Selective: bile salts inhibit Streptococcus
108
Differentiation of bile esculin broth
Tests ability to hydrolyze esculin to glucose and esculetin (black complex)
109
E. faecalis: bile esculin broth results
Black color produced: can grow and produces esculetin
110
MacConkey agar: selective, differential, or both
Selective and differential
111
Selectivity of MacConkey agar
Crystal violet inhibits gram + bacteria, so gram - bacteria are selected
112
Differentiation of MacConkey agar
Lactose with neutral red dye in media: lactose fermentors appear pink, non-fermentors such as Salmonella appear colorless to yellow
113
E. coli: MacConkey agar results
Growth, pink color due to lactose fermentation
114
Ashby's nitrogen free agar: selective, differential, or both
Selective, non-differential
115
Selectivity of Ashby's nitrogen free agar
Microorganisms that fix atmospheric nitrogen grow
116
Azotobacter: Ashby's nitrogen free agar results
Growth: can fix N2
117
Tryptic soy agar (TSA) and Luria Bertani: selective, differential, both, or neither
Non-selective, non-differential
118
CNA stands for what? What is an active ingredient of it?
Colistin-Nalidixic acid
| Contains blood
119
CNA: selective, differential, or both
Selective and differential
120
Selectivity of CNA
Gram + bacteria grow: colistin disrupts lipids and LPS in gram - outer membrane
121
Bacillus are gram positive, so do they grow on CNA?
Most strains don't grow on CNA
122
Differentiation of CNA
Blood enables detection of hemolytic activity
123
What are the 3 types of hemolytic activity, and how are they detected?
Alpha: partial lysis of RBCs, green color
Beta: complete lysis of RBCs, transparent color
Gamma: no lysis of RBCs, no change in agar
124
Pseudomonas enrichment benzoate medium: Pseudomonas can convert ______ in medium to _____ and _____, which can be used in the _____ _____.
Hydroxybenzoate
Acetyl-CoA
Succinate
TCA cycle
125
PAF plate: PAF stands for what?
Pseudomonas agar F
126
PAP plate: PAP stands for what?
Pseudomonas agar P
127
PAF and PAP plates: selective, differential, or both?
Non-selective
| Differential
128
Differentiation of PAF plate
Color change is produced for pyoverdin
129
What color does P. aeruginosa produce on PAF plate? What color does P. fluorescens produce on PAF plate?
P. aeruginosa: green
| P. fluorescens: yellow
130
Differentiation of PAP plate
Color change is produced for pyocyanin
131
What species of Pseudomonas produces pyocyanin? What color is pyocyanin?
P. aeruginosa
| Blue
132
Mannitol salt agar: selective, differential, or both?
Selective and differential
133
Selectivity of mannitol salt agar
High salt concentration inhibits all growth except Staphylococcus
134
Differentiation of mannitol salt agar
Mannitol fermentors turn agar yellow (acid formation)
135
Mannitol salt agar results for S. aureus and S. epidermidis
S. aureus: yellow
| S. epidermidis: red (no change)
136
Blood agar: selective, differential, or both?
Differential
137
Differentiation of blood agar
Blood enables detection of hemolytic activity
138
Beta hemolysis: 3 organisms
E. coli
S. aureus
Streptococcus pyogenes
139
Alpha hemolysis: organism
Streptococcus pneumoniae
140
Gamma hemolysis: 2 organisms
Staphylococcus epidermidis
| Enterococcus
141
DNase test agar: 2 possible indicators
Toluidine blue
| Methyl green
142
DNase: selective, differential, or both?
Selective and differential
143
Selectivity of DNase
Methyl green inhibits some gram positive organisms
144
Differentiation of DNase
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
2 DNase positive organisms and 2 DNase negative organisms
DNase positive: Serratia, S. aureus
| DNase negative: Enterobacter, S. epidermidis, E. coli
146
Oxidase test determines presence of what enzyme? What metabolic process is this enzyme involved in?
Cytochrome oxidase
| Involved in electron transport
147
How oxidase test works: name of indicator, what is done to it, what is final result
Indicator: tetramethylphenylenediamine dihydrochloride
Oxidized
Production of purple color
148
2 oxidase positive organisms
Azotobacter
| Pseudomonas
149
4 oxidase negative organisms
Escherichia, Staphylococcus, Enterococcus, Streptococcus
150
What organisms can be either oxidase positive or negative?
Bacillus
| Azotobacter
151
Catalase test: how does it work? Ingredient? Reaction? Final result?
Hydrogen peroxide detects presence of catalase
H2O2 -> H2O + O2
Bubbles formed: positive test
152
Catalase test can be used to differentiate members of what 2 genera?
Staphylococcus: positive
Streptococcus: negative
153
2 organisms that are catalase negative
Streptococcus
| Enterococcus
154
Biofilms
Multicellular, surface-attached communities
155
Are biofilms always made up of members of the same species, or can there be multiple species present?
Can be either
156
Where do biofilms form in aquatic habitats (3)? What can they form on in the human body (2)?
Rocks
Water lines
Hulls of ships
Catheters, implants of hip and knee
157
3 stages of biofilm development
Attachment
Colonization
Development
158
Attachment stage of biofilm development
Individual bacteria transition from planktonic (free-living) cells to adherent surface attached cells
159
What 2 types of cell-wall associated structures assist in attachment of bacteria in a biofilm?
Pili
| Fimbriae
160
Colonization stage of biofilm development
Attached cells begin synthesizing and releasing polysaccharides, proteins, and DNA, forming protective matrix
161
Matrix formed during colonization of biofilm serves what 2 functions?
Trap nutrients
| Protection from harmful agents (antibiotics, host immune response)
162
Development stage of biofilm formation
Mushroom-like colonies of bacteria are formed
| Contain channels through which nutrients flow and feed biofilm
163
Quorum sensing: what is it, what stages of biofilm development is it associated with
Communication between bacteria by sending and receiving chemical signals
Both colonization and development stages
164
How biofilm formation was measured in lab
Optical density: higher OD value, greater biofilm-forming ability
165
3 species of bacteria used in biofilm experiment: names, which was best biofilm former
E. coli, S. epidermidis, P. fluorescens
| Best biofilm former: P. fluorescens
166
Which temperature, 30 or 37 degrees Celsius, was more favorable to biofilm formation?
37 degrees Celsius
