Lab exam FINAL Flashcards
1
Q
what are the four steps of differential staining?
A
- primary stain - colors the target cell
- mordant - helps color stick in target cells
- decolorizer - removes color from background and non-target cells
- counterstain - stains non-target cells
2
Q
what are the four chemicals used for gram stain?
A
- primary stain: crystal violet
- mordant: iodine
- decolorizer: acetone/alcohol
- counterstain: safranin
3
Q
what is the primary stain in gram staining?
A
crystal violet
4
Q
what is the mordant in gram staining?
A
iodine
5
Q
what is the decolorizer used in gram staining?
A
alcohol and acetone
6
Q
what is the counterstain used in gram staining?
A
safranin
7
Q
what were the target and non-target cells used in gram stain? what color should they have been?
A
target: Staphylococcus aureus - purple
non-target: Escherichia coli - pink
8
Q
what are the four chemicals used for acid fast stain?
A
- primary stain: basic fuchsin
- mordant: phenol + dimethyl sulfoxide
- decolorizer: acid-alcohol
- counterstain: methylene blue
9
Q
what were the target and non-target cells used in acid fast stain? what color should they have been?
A
target: Mycobacterium smegmatis - pink
non-target: Staphylococcus aureus - blue
10
Q
what are the four chemicals used for endospore stain?
A
- primary stain: malachite green
- mordant: steam
- decolorizer: distilled water
- counterstain: safranin
11
Q
what were the target and non-target cells used in endospore stain? what color should they have been?
A
target: endospores - green
non-target: vegetative cells - pink
12
Q
what is the primary stain in capsule staining?
A
congo red
13
Q
what is the purpose of the acid-alcohol for the capsule stain? how is this different than how it was used for acid-fast?
A
In capsule staining, acid-alcohol chemically fixes the cells to the slide
In acid-fast, acid-alcohol is used as the decolorizer
14
Q
what is the secondary stain used in capsule staining?
A
carbol fuchsin
15
Q
How do capsules appear at the end of capsule staining?
A
background will be dark blue/purple and magenta
capsules will look like a clear halo around the pinkish color of the bacillus shaped cell
16
Q
what was the target bacteria in capsule stain? what color?
A
Klebsiella pneumoniae - mostly colorless
17
Q
what is the purpose of streak plating?
A
to produce pure, isolated colonies from a mixed sample
18
Q
what antibiotic was most and least effective?
A
Most: Chloramphenicol
Least: Bacitracin
19
Q
Which bacterial type is the most and least susceptible to antibiotics?
A
most susceptible: Mycobacterium smegmatis
least susceptible: Escherichia coli
20
Q
what does the death zone of a susceptible organism look like?
A
large death zone
21
Q
what does the death zone of a resistant organism look like?
A
small/no death zone
22
Q
what antiseptic was most and least effective?
A
Most effective – 1% formaldehyde
Least effective – 70% isopropyl alcohol
23
Q
which bacterial type is the most and least susceptible to antiseptics?
A
most susceptible: Mycobacterium smegmatis
least susceptible: Escherichia coli
24
Q
what is the equation to convert Celsius to Fahrenheit
A
°F = (°C x 1.8) + 32
25
what is refrigerator temp in Celsius?
4 °C
26
what is room temp in Celsius?
25 °C
27
what is body temp in Celsius?
37 °C
28
what is the definition of selective media?
inhibits growth of unwanted microbes (only the selected microbes live)
29
what is the definition of differential media?
allows organisms to grow but the added chemicals make them look different (they change different colors and/or precipitate is visible)
30
What did MSA stand for? Whats the original color?
MSA: Mannitol salt agar
red
31
How is MSA selective?
selects for gram +
selects against gram -
32
How is MSA differential? (fermentation?)
differential for mannitol fermentation
33
what are the possible bacteria and colors produced by inoculating MSA plate?
fermenter: growth turns yellow (Staphylococcus aureus)
nonfermenter: growth remains red (Staphylococcus epidermidis)
34
What did EMB stand for? Whats the original color?
EMB: Eosin methylene blue
dark purple
35
how is EMB selective?
selects for gram -
selects against gram +
36
how is EMB differential? (fermentation?)
differential for lactose fermentation
37
what are the possible bacteria and colors produced by inoculating EMB plate?
strong fermenter: growth turns shiny metallic green (Escherichia coli)
weak fermenter: growth turns pink around the edges of colonies (Enterobacter aerogenes)
nonfermenter: growth remains dark purple (Proteus vulgaris)
38
What did MAC stand for? Whats the original color?
MAC: MacConkey agar
raspberry
39
how is MAC selective?
selects for gram -
selects against gram +
40
how is MAC differential? (fermentation?)
differential for lactose fermentation
41
what are the possible bacteria and colors produced by inoculating MAC plate?
strong fermenter: entire plate turns bright pink (Escherichia coli)
weak fermenter: growth turns light pink with precipitate and background turns light brown (Enterobacter aerogenes)
nonfermenter: entire plate turns brown (Proteus vulgaris)
42
which plate used in lab this semester was not selective or differential?
TSA, Tryptic soy agar
43
which organisms used in the S&D exercise are Gram + ?
Staphylococcus aureus
Staphylococcus epidermidis
44
which organisms used in the S&D exercise are Gram - ?
- Escherichia coli
- Enterobacter aerogenes
- Proteus vulgaris
45
what genus is used for the gram + sphere project?
Staphylococcus
46
Gram + Sphere Unknown (Staphylococcal)
what are the potential species used within the gram + sphere project?
Staphylococcus aureus
Staphylococcus capitis
Staphylococcus epidermidis
Staphylococcus haemolyticus
Staphylococcus lentus
Staphylococcus saprophyticus
47
Gram + Sphere Unknown (Staphylococcal)
What type of media was used to test for growth at elevated temperature?
TSB
48
Gram + Sphere Unknown (Staphylococcal)
what was a positive/negative result for the test for growth at elevated temperature?
positive: turbid = indicated that growth was present
negative: clear = growth not present
49
Gram + Sphere Unknown (Staphylococcal)
Which elevated temperature was used to differentiate between species of Staphylococcus?
45C or 113F
50
what tool did we use to inoculate the 45 degree experiment?
cotton swab
51
Gram + Sphere Unknown (Staphylococcal)
Is urea a product or reactant for this test?
Urea is the reactant
52
what tool was used to inoculate the urea agar slant?
loop
53
Gram + Sphere Unknown (Staphylococcal)
What are the two products of the enzyme urease? Know how to write out the molecular formula of each of these products
ammonia + carbon dioxide
54
what is the original media color of urea agar slant?
peach color
55
Gram + Sphere Unknown (Staphylococcal)
Which product of urease changes the pH of the sample tube?
ammonia
56
Gram + Sphere Unknown (Staphylococcal)
Will a tube that is positive for urease activity become more acidic or more alkaline?
Alkaline
57
Gram + Sphere Unknown (Staphylococcal)
What is the weak acid/weak base pair that is produced by urease activity?
carbon dioxide = weak acid
ammonia = weak base
58
what was the reaction for the substrate and products of the urea agar slant?
59
Gram + Sphere Unknown (Staphylococcal)
what gives a pos/neg result in the urea agar slant?
pos: hot pink color change = ^ pH
neg: yellow color change = v pH
60
Gram + Sphere Unknown (Staphylococcal)
What kind of molecule is trehalose?
plant carbohydrate
61
Gram + Sphere Unknown (Staphylococcal)
Is trehalose a product or a reactant for this test?
Trehalose is the reactant
62
Gram + Sphere Unknown (Staphylococcal)
- Which pH indicator is used in a trehalose agar stab?
Phenol red
63
Gram + Sphere Unknown (Staphylococcal)
- Which tool is used to inoculate an agar stab?
needle
64
Gram + Sphere Unknown (Staphylococcal)
Trehalose stab:
- What color will this pH indicator be with a positive test for fermentation?
Yellow color change (pH goes down)
65
Gram + Sphere Unknown (Staphylococcal)
What is the name of the toxin that destroys red blood cells?
hemolysin
66
Gram + Sphere Unknown (Staphylococcal)
What would a positive blood agar test result look like for the BLood agar test?
What does this indicate?
Red color disappears under colonies
Indicates that hemolysin production occurred
67
What tools did we use to inoculate the blood agar plate? what technique?
Cotton swab
Zag plating technique
68
Gram + Sphere Unknown (Staphylococcal)
Which Greek letter is used to describe a positive test result?
Beta patter (clearance zone)
69
Gram + Sphere Unknown (Staphylococcal)
Which Greek letter is used to describe a negative test result?
Gamma pattern (no clearance zone)
70
Gram + Sphere Unknown (Staphylococcal)
What type of agar is used to screen for antibiotic sensitivity of our unknown?
what is the test called?
what plating technique was used?
TSA
Novobiocin resistance test
Lawn plate technique
71
Gram + Sphere Unknown (Staphylococcal)
How does novobiocin inhibit bacterial growth?
Novobiocin is an antibiotic that acts as DNA synthesis inhibitor to bacteria
72
Gram + Sphere Unknown (Staphylococcal)
What would a pos/neg test result for novobiocin resistance look like?
pos: no death zone = resistant
neg: large death zone >4 mm = susceptible
73
Gram + Sphere Unknown (Staphylococcal) (nitrate broth)
Which form of metabolism utilizes nitrate salt as a terminal electron acceptor?
anaerobic respirator
74
what did the nitrate broth test for?
tests for nitrate respiration
75
Gram + Sphere Unknown (Staphylococcal)
Is nitrate an oxidized or a reduced salt? what does this mean?
oxidized salt
it can accept electrons
76
Gram + Sphere Unknown (Staphylococcal)
what is the equation for nitrate being successfully oxidized in the nitrate test?
Nitrate --> Nitrite --> Nitrous Oxide ---> Nitrogen gas --> Amonia
No3- --> No2- --> N2O ----------------> N2(g) ------------> NH3
(color change) ( trapped in Durham tube )
77
Gram + Sphere Unknown (Staphylococcal)
Which of these reduced products are gases?
nitrous oxide (N2O)
nitrogen gas (N2)
78
Gram + Sphere Unknown (Staphylococcal)
Which color is produced by a positive nitrite test?
Color changes to Red and maybe gas bubbles
79
Gram + Sphere Unknown (Staphylococcal)
- Is a positive nitrite test a positive or negative result for nitrate reduction?
positive nitrite test (red color change) indicates that your organism reduced nitrate to nitrite. (positive for nitrate reduction)
80
Gram + Sphere Unknown (Staphylococcal)
What is the function of a Durham tube?
to trap any potential gasses
81
Gram + Sphere Unknown (Staphylococcal)
Is the presence of bubbles in the Durham tube positive or negative for nitrate reduction?
positive
82
Gram + Sphere Unknown (Staphylococcal)
What would the results look like for an organism that did not use the nitrate?
Neg: color remains clear and no bubbles
83
Gram + Sphere Unknown (Staphylococcal)
Gelatin is what type of biological molecule?
protein
84
Gram + Sphere Unknown (Staphylococcal)
- What is the name of the enzyme that hydrolyzes (breaks down) gelatin?
protease
85
Gram + Sphere Unknown (Staphylococcal)
How did we inoculate the gelatin agar so that it could be incubated?
needle
86
Gram + Sphere Unknown (Staphylococcal)
If we were to analyze the tubes for gelatin hydrolysis directly after removing the cultures from the incubator our results would be incorrect. What do we need to do before analyzing the results of our hydrolysis test?
allow them to chill
87
Gram + Sphere Unknown (Staphylococcal)
Briefly describe the appearance of a tube that is positive for gelatin hydrolysis.
Whats negative look like?
pos: liquid after chilled = break down into amino acids occurred
neg: solid after chilled = break down did not occur
88
Gram + Sphere Unknown (Staphylococcal)
what does the Vogel Johnson Agar test for?
mannitol fermentation
coagulase production
89
what chemicals are in Vogel Johnson Agar? what do they serve as?
tellurite and lithium chloride
selective chemicals
90
what tool and what technique is used within the Vogel Johnson Agar experiment?
cotton swab
zag plating technique
91
what causes the broth to coagulate?
Coagulase
92
Gram + Sphere Unknown (Staphylococcal)
In the Vogel Johnson Agar test, how are black colonies formed?
tellurite gets reduced to tellurium when coagulase is present
93
Gram + Sphere Unknown (Staphylococcal)
What concentration of NaCl is used in our hypertonic broth?
6.5%
94
Gram + Sphere Unknown (Staphylococcal)
what was the pH indicator of the sodium chloride broth?
bromocresol purple
95
What tools did we use for the sodium chloride broth?
loop
96
Gram + Sphere Unknown (Staphylococcal)
What was the color of the sodium chloride broth before incoluation?
purple
97
Gram + Sphere Unknown (Staphylococcal)
What color is expected with a positive test result in the NaCl broth test?
Yellow color change (pH goes down)
Bacteria survived and grew
98
Gram - Rod Unknown
what are a few of the potential genera used in the gram - rod unknown experiment?
Citrobacter freundii
Enterobacter aerogenes
Escherichia coli
Klebsiella pneumoniae
Proteus vulgaris
Pseudomonas aeruginosa
99
Gram - Rod Unknown
what does a pos/neg test look like for the catalase test?
pos: bubble formation after H2O2 is added
neg: no bubbles formed after H2O2 is added
100
Gram - Rod Unknown
-
What type of media was used for the catalase test?
TSA
(In a slant)
101
Gram - Rod Unknown
write out the complete catalase reaction, including the names and molecular formulas of all substrates and products.
H2O2 --catalase--> H2O + O2 (forms bubbles)
102
Gram - Rod Unknown
Which product of catalase activity is responsible for the visible reaction?
oxygen gas
103
Gram - Rod Unknown
Which substrate is broken down by catalase?
Hydrogen peroxide (H2O2)
104
Gram - Rod Unknown
what is a pos/neg result for the simmons’ slant?
pos: blue color change
Neg: color remains green
105
What is the pH indicator of the simmons slant?
Bromothymol blue
106
Gram - Rod Unknown
What color is a Simmons’ slant that is positive for nutrient utilization?
Blue
107
Gram - Rod Unknown
What color is the Simmons slant tube before it is incubated?
Green
108
Gram - Rod Unknown
What is the carbon source in the Simmons’ slant?
citrate
109
Gram - Rod Unknown
What is the nitrogen source in the Simmons’ slant?
ammonium
110
Gram - Rod Unknown
- How does nutrient utilization affect the pH of the Simmons’ slant?
what happens to the ammonium as well?
citrate utilization removes citrate (acidic) from media which increases pH
ammonium (NH4+) gets reduced to ammonia (NH3)
111
Gram - Rod Unknown
Litmus milk broth contains two key ingredients, which are..
skim milk and litmus powder
112
Gram - Rod Unknown
What are the two functions of the litmus powder in the litmus milk broth?
1. pH indicator --> change color based on fermentation of lactose
2. Used as electron acceptor (can be reduced)
113
Gram - Rod Unknown
What are the three reactions that can occur with the litmus powder?
Alkaline result: No lactose fermentation / purple color
Acidic result: Positive fpr lactose fermantation / pink color change
Reduction of litmus: White band that sinks to the bottom of tube
114
WHat does an alkaline result look like with the litmus powder?
Alkaline result: No lactose fermentation / purple color
115
WHat does an acidic result look like with the litmus powder?
Acidic result: Positive fpr lactose fermantation / pink color change
116
WHat does a reduction of litmus result look like with the litmus powder?
Reduction of litmus: White band that sinks to the bottom of tube
117
Gram - Rod Unknown
What are the two possible reactions that can occur with the milk protein in the litmus milk broth?
Protein results (peptonization) media is more clear
Coagulation (solid formation due to casin in the milk coagulating w/acid)
118
Gram - Rod Unknown
WHat is peptonization?
Protein is utilized which removes the cloudiness
119
Gram - Rod Unknown
What causes the broth to coagulate in the litmus test?
casein not being used, and instead clumping with the acids
120
Gram - Rod Unknown
- What does the abbreviation ‘SIM’ stand for?
Sulfide Indole Motility
121
Gram - Rod Unknown
Which of the three tests did we not record data for? why?
motility
because some results would be black in color and would be too hard to see microbes being motile
122
Gram - Rod Unknown
- Which amino acid is degraded to produce ‘S’?
cysteine
123
Gram - Rod Unknown
- What is the enzyme that is responsible for ‘S’?
cysteine desulferase
124
Gram - Rod Unknown
- What are the three products that are produced as part of ‘S’?
125
Gram - Rod Unknown
Which specific product of the three is detected by ‘S’?
hydrogen sulfoxide
126
Gram - Rod Unknown
What color is a positive/neg ‘S’ test?
pos: black color change
neg: no color change (remains plain broth)
127
Gram - Rod Unknown
Which amino acid is degraded to produce ‘I’?
tryptophan
128
Gram - Rod Unknown
- What is the enzyme that is responsible for ‘I’?
tryptophanase
129
Gram - Rod Unknown
- What are the three products that are produced as part of ‘I’?
Tryptophan -- tryptophanase --> Nh3 + Indole + Pyruvate
130
Gram - Rod Unknown
Which specific product of the three is detected by ‘I’?
indole
131
Gram - Rod Unknown
What reagent is used to test for ‘I’?
Kovac’s reagent
132
Gram - Rod Unknown
what does a pos/neg look like for ‘I’ test?
pos: red ring on top of stab
neg: no color change but drops of reagent remain yellow
133
Gram - Rod Unknown
What does the abbreviation ‘MRVP’ stand for?
Methly Red Vogues Proskaver
134
what does the MR in MRVP test for? what reagent is testing for this?
methyl red reagent (pH indicator) - tests for mixed acids (lactic, formic, etc.)
135
Gram - Rod Unknown
- Which reagent tests for the production of mixed acids by fermentation?
Methly red, after incubation
136
Gram - Rod Unknown
How does the color of the reagent that tests for mixed acid fermentation change with decreasing pH? Mvrp
Red color change (acidic result)
137
How does the color of the reagent that tests for mixed acid fermentation look like with negative change?
Yellow color change (neutral)
138
What goes the Vogues Proskaver test for?
Testing for alcohol fermentation
139
Gram - Rod Unknown
- How many days does the 2,3-butanediol test using an MRVP tube incubate for?
5 days
140
Gram - Rod Unknown
- Why doesn’t 2,3-butanediol react with a pH indicator, like phenol red?
Because alcohol has a ph of 7
141
Gram - Rod Unknown
- What is the exact procedure for performing the VP test in lab?
142
Gram - Rod Unknown
- What is the purpose of shaking the small tube?
To oxidize the acetoin
143
Gram - Rod Unknown
-Which final chemical product will be created in the vogues proskaver test?
diacetyl (wat we detect)
144
Gram - Rod Unknown
- How long does the VP test sit before the color change is complete?
30mins
145
Gram - Rod Unknown
- What color is a positive VP test? What color is a negative test result?
Positive: Deep red
Neg: Brown
146
Gram - Rod Unknown
- What kills Gram + & some Gram – in the Brilliant Green Agar?
brilliant green dye
147
Gram - Rod Unknown
-What sugars are found in the Brilliant Green?
Lactose and Sucrose
148
Gram - Rod Unknown
-What is the pH indicator for the BG agar?
Low pH = ferments sugar
High pH = Prefers peptides
149
Gram - Rod Unknown
- What color is brilliant green agar that is positive for fermentation (Acidic)? Is there growth?
Lime green color change with no grown
150
Gram - Rod Unknown
- What color is brilliant green agar that is negative for fermentation (Basic)?
Bright pink color change
151
Gram - Rod Unknown
- What color is brilliant green agar when the bacteria is dead (Also negative)?
Plate stays orange (original color)
152
What does the Oxidase slant test for?
Testing for cytochrome oxidase
153
Gram - Rod Unknown
What is the protein cytochrome oxidase normally used forin the oxidase slant?
transfers electrons from cytochrome C (protein) into oxygen
154
Gram - Rod Unknown
Where specifically is cytochrome oxidase located?
Cytochrome oxidase is used in the electron transport chain (ETC)
155
Gram - Rod Unknown
what is the reaction associated with oxidase test?
2e- + 2H+ + 1/2O2 ---> H2O
156
Gram - Rod Unknown
- What color is a pos/neg cytochrome oxidase test?
pos: dark purple color change w/in 20 seconds
neg: no color change w/in 20 seconds (remains plain agar)
157
Gram - Rod Unknown
- What type of media was used for the oxidase test?
TSA slant
158
Gram - Rod Unknown
-What is in the Hektoen agar that makes it selective?
bile
159
Gram - Rod Unknown
- What three carbohydrates does it contain?
Lactose, sucrose, salicin
160
Gram - Rod Unknown
-What are the pH indicators in the Hektoen agar?
161
Gram - Rod Unknown
- What is the fermentation color change in the Hektoen agar? is there growth? Is it alkaline or acidic?
Orange color change (growth and acidic)
162
Gram - Rod Unknown
-What is the non-fermenter color change for Hektoen agar?
Blue/Green color change
