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Lab- Microbiology > Lab Exam 3 > Flashcards

Lab Exam 3 Flashcards

(103 cards)

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1
Q

Gram + Sphere
- Which genus was used for this experiment?

A

Staphylococcus

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2
Q

Gram + Sphere
- Potential species used:

A
  • S. aureus
  • S. epidermidis
  • S. lentus
  • S. capitis
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3
Q

Gram + Sphere
- Growth at 45C

A

Tests for growth at elevated temp.
- positive: cloudy / growth
- negative: clear broth/ no growth

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4
Q

Gram + Sphere
- Urea Agar slant

A

Tests for urease production.
- Positive: hot pink color change (alkaline pH)
- Negative: yellow color change (acidic pH)

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5
Q

Gram + Sphere
- Vogel Johnson Agar

A
  • Tests for mannitol fermentation and coagulase production
    > Tellurite & lithium chloride can inhibit certain bacteria (selective)
  1. Mannitol:
    positive= yellow color/ Negative= stays red
  2. Coagulase production:
    Positive= black colonies/ Negative= no black colonies
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6
Q

Gram + Sphere
- Vogel Johnson Agar: Coagulase

A

Positive: Black colonies form due to tellurite reduced to tellurium

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7
Q

Gram + Sphere
- Which elevated temperature was used to differentiate between species of Staphylococcus? (F and C)

A

45C
113F

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8
Q

Gram + Sphere
What type of media was used to test for growth at elevated temperature?

A

TSB= Tryptic soy broth

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9
Q

Gram + Sphere
- Is urea a product or reactant for this test?

A

Reactant

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10
Q

Gram + Sphere
- What are the two products of the enzyme urease?

A

Ammonia and Carbon dioxide
CO(NH2)2+H2O–> 2NH3+CO2
Urea+water–makes–>urease enzyme->ammonia->carbon dioxide

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11
Q

Gram + Sphere
- Which product of urease changes the pH of the sample tube?

A

Ammonia (weak base, alkaline)

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12
Q

Gram + Sphere
- Which pH indicator is used in an urea agar slant?

A

Phenol red (???????)

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13
Q

Gram + Sphere
What is the weak acid/weak base pair that is produced by urease activity?

A

Weak acid:
Weak base: ammonia NH3

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14
Q

Gram + Sphere
- Trehalose stab

A

Tests for trehalose fermentation
- Positive: yellow color (pH decreases)
- Negative: no change (neutral)

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15
Q

Gram + Sphere
What kind of molecule is trehalose?

A

Trehalose is an odd plant carbohydrate

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16
Q

Gram + Sphere
Which pH indicator is used in Trehalose stab?

A

Phenol red

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17
Q

Gram + Sphere
- Which tool is used to inoculate an agar stab?

A

Needle

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18
Q

Gram + Sphere
- Blood agar (swab/zag)

A

Tests for hemolysin production
-Positive: Clearance zone (see through), called beta pattern (B) = hemolysin production
-Negative: No clearance zone (growth) called gamma pattern (y) = no hemolysin produced

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19
Q

Gram + Sphere
- What is the name of the toxin that destroys RBCs?

A

Hemolysin

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20
Q

Gram + Sphere
- What type of agar is used to screen for antibiotic sensitivity?

A

TSA= tryptic soy agar (???)

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21
Q

Gram + Sphere
- Which plating technique is used to prepare this plate for antibiotic resistance?

A

Lawn plate (swab)

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22
Q

Gram + Sphere
- How does novobiocin inhibits bacterial growth?

A

DNA synthesis inhibitor

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23
Q

Gram + Sphere
- Novobiocin resistance

A
  • Positive: no death zone
  • Negative: Larger death zone > 4mm
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24
Q

Gram + Sphere
- Nitrate broth (loop)

A

Tests for nitrate respiration
- Positive: red color and maybe bubbles after drops
*Nitrite causes red color change// Durham tube traps gas
-Negative: no change no bubbles

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25
Gram + Sphere - Which form of metabolism utilizes nitrate salt as a terminal electron acceptor?
Anaerobic respiration (???????)
26
Gram + Sphere - Is nitrate an oxidized or reduced salt?
Oxidized salt
27
Gram + Sphere - Molecular formula of nitrate:
NO3-
28
Gram + Sphere - How is nitrate reduced to ammonia?
Nitrate->Nitrite->Nitrous oxide->Nitrogen gas->ammonia NO3- ->NO2- -> N2O (g) -> N2 (g) -> NH3
29
Gram + Sphere - Know the molecular formulas of possible products of nitrate reduction:
- Nitrate: NO3- - Nitrite: NO2- - Nitrous oxide: N2O (g) - Nitrogen gas: N2 (g)
30
Gram + Sphere - Gelatin stab (needle)
Tests for gelatin protein utilization. - Positive: liquid after chilled (enzyme protease degrades gelatin to its amino acids=liquid) - Negative: stays solid after chilled
31
Gram + Sphere - Gelatin is what type of biological molecule?
Protein
32
Gram + Sphere - What is the name of the enzyme that hydrolyzes gelatin?
Protease
33
Gram + Sphere - How did we inoculate the gelatin agar so that it could be incubated?
Stab with needle
34
Gram + Sphere - 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?
Needs to be chilled
35
Gram + Sphere - 6.5 NaCl broth (loop)
6.5% Sodium Chloride broth - Initial color of broth: Purple - Tests for growth in a high salinity broth/environment -pH indicator: bromocresol purple > Positive: Yellow color change/growth (pH down/acidic) (organism can survive in this environment) > Negative: No color change/ no growth (neutral)
36
Gram - Rod Unknown - Potential genera used:
- Citrobacter freundii - Enterobacter aerogenes - Escherichia coli - Pseudomonas aeruginosa - Proteus vulgaris - Klebsiella pneumoniae
37
Gram - Rod Unknown - Simmons' slant:
- Tests for citrate & ammonium utilization - pH indicator: Bromothymol blue. > Positive: Blue color change > Negative: Stays green
38
Gram - Rod Unknown - How does nutrient utilization affect the pH of the Simmons' slant?
When citrate gets utilized, acidity leaves the media = increased pH (alkaline).
39
Gram - Rod Unknown What color is Simmons' slant tube before inoculated and incubated?
Green
40
Gram - Rod Unknown - What is the carbon and nitrogen source in the Simmons' slant?
Carbon: Citrate Nitrogen: Ammonium
41
Gram - Rod Unknown - Litmus milk broth contains two key ingredients:
> Skim milk: Can be used as a nutrient > Litmus powder: - pH indicator: color change based on fermentation or not - Electron acceptor: can be reduced.
42
Gram - Rod Unknown - Litmus powder reactions:
- Acidic: Pink color change= lactose fermentation (pH -) eats sugar. - Alkaline: Stays purple= lactose non-fermentor (pH +) eats protein - Reduction: White color (sinks over time)
43
Gram - Rod Unknown - Litmus: skim milk reactions:
- Coagulation: Solid/ casein in the media forms a solid due to too much acid released. - Peptonization: Cloudiness is removed, band of transparent media (should only happen in a purple media)
44
Gram - Rod Unknown - What does SIM stand for?
- Sulfide: tests for cysteine breakdown - Indole: Tests for tryptophan breakdown - Motility (data wasn't collected; would be too hard to see microbes being motile)
45
Gram - Rod Unknown - What amino acid is degraded to produce 'S'?
Cysteine
46
Gram - Rod Unknown - What is the enzyme is responsible for 'S'?
Cysteine desulferase
47
Gram - Rod Unknown - What are the products that are produced as part of 'S'?
- Ammonia NH3 - Hydrogen Sulfoxide: H2S (what we detect) - Pyruvate
48
Gram - Rod Unknown - Results for 'S'
- Positive: Black color change (because H2S reacts with iron ions in the media) - Negative: No color change
49
Gram - Rod Unknown - Which amino acid is degraded to produce 'I'?
- Tryptophan
50
Gram - Rod Unknown - What is the enzyme that is responsible for 'I'?
Tryptophanase
51
Gram - Rod Unknown - What are the three products that are produced as part of 'I'?
- Ammonia NH3 - Indole (what we detect) - Pyruvate
52
Gram - Rod Unknown - What reagent is used to test for 'I'?
Kovac's reagent drops (10-12)
53
Gram - Rod Unknown - Results for 'I':
- Positive: red ring on top - Negative: no color change (yellow from drops)
54
Gram - Rod Unknown - What does the abbreviation MRVP stand for?
-MR: Methyl Red= tests for mixed acid - VP: Vogues Proskauer= detects alcohol fermentation 2,3-butanediol
55
Gram - Rod Unknown - Which reagent tests for the production of mixed acids by fermentation?
Methyl red (after incubation) - Positive: red color change (acidic, pH -) - Negative: Yellow color change (neutral)
56
Gram - Rod Unknown - How many days does the 2,3-butanediol test using an MRVP tube incubate for?
5 days
57
Gram - Rod Unknown - Why doesn't 2,3-butanediol reacts with a pH indicator like phenol red?
Because its pH neutral (?????????????????????)
58
Gram - Rod Unknown - What is the exact procedure for performing the VP test in lab?
After incubating for 5 days, we add 18 drops of reagent A & 18 of reagent B. If the intermediate molecule ACETOIN is present, it is oxidized into DIACETYL (what we detect)
59
Gram - Rod Unknown - What is the purpose of shaking the small tube (VP)?
Oxidize acetoin into diacetyl
60
Gram - Rod Unknown - How long does the VP test sit before the color change is complete?
30 min
61
Gram - Rod Unknown - VP color results:
- Positive: Deep red - Negative: Brown
62
Gram - Rod Unknown - Brilliant Green Agar (zag)
- Tests for lactose and sucrose fermentation - Fermentor will decrease the pH of the plate (acidic) - Non-fermentor is utilizing the peptides in the plate (pH goes up=alkaline and Releases ammonia as a by product.
63
Gram - Rod Unknown - What kills Gram + and some Gram - in the Brilliant Green Agar?
Brilliant green dye
64
Gram - Rod Unknown - 2 Sugars found in Brilliant Green Agar:
- Lactose - Sucrose
65
Gram - Rod Unknown - What is the pH indicator for Brilliant Green Agar?
phenol red
66
Gram - Rod Unknown - Brilliant Green Agar color results:
- Acidic: Fermenter= Lime green color - Alkaline: Non-fermenter= Bright pink - Dead: inhibited by green dye, no growth no color, stays orange.
67
Gram - Rod Unknown - What type of media was used for the catalase test?
- agar slant TSA
68
Gram - Rod Unknown - Which substrate is broken down by catalase?
Hydrogen peroxide (H2O2)
69
Gram - Rod Unknown - write down the Catalase reaction:
H2O2---catalase-->H2O+O2
70
Gram - Rod Unknown - Catalase slant:
- Testing for catalase production. - Positive: Bubble formation from O2 gas - Negative: no bubbles (anaerobic)
71
Gram - Rod Unknown - Which product of catalase is responsible for the visible reaction?
O2 gas (what we detect)
72
Gram - Rod Unknown - what is the protein cytochrome oxidase normally used for?
To transfer electrons from cytochrome c (protein) to to oxygen.
73
Gram - Rod Unknown - Where specifically is cytochrome oxidase located?
Cytochrome oxidase is a component in the ETC (electron transport chain)
74
Gram - Rod Unknown - Reaction of cytochrome oxidase:
2e- + 2H+ + 1/2O2 —> H2O
75
Gram - Rod Unknown - Cytochrome oxidase results:
- Testing for the presence of cytochrome oxidase (in TSA slant) -Positive: Dark purple color change - Neg: No color change (both reactions w/in 20 sec)
76
Gram - Rod Unknown - What is in the Hektoen agar that makes it selective?
Bile. Inhibits Gram + and certain Gram -
77
Gram - Rod Unknown - What 3 carbohydrates does Hektoen agar contain?
- Lactose - Sucrose - Salicin (from willow bark)
78
Gram - Rod Unknown - 2 Hektoen agar pH indicators:
Bromothymol blue and acid fuchsin
79
Gram - Rod Unknown - Hektoen agar results:
- Acidic: Fermenter/ orange color change - Alkaline: non-fermenter/ blue green color - Dead: Inhibited by bile/ plate stays forest green, no growth
80
4 steps of differential staining:
1. primary (differential) stain - colors the target cell 2. mordant - helps color stick in target cells 3. decolorizer - removes color from background and non-target cells 4. counterstain - stains non-target cells
81
- Gram Stain
- primary stain: crystal violet - mordant: iodine - decolorizer: acetone/alcohol - counterstain: safranin
82
- Bacteria used for Gram Stain
- S. aureus. Gram +, purple, coccus O (target) - E. Coli, Gram -, pink, bacillus
83
- Acid fast stain
- Primary stain: basic fucsin - Mordant: phenol+ dimethyl sulfoxide - Decolorizer: acid alcohol - Counterstain: methylene blue
84
- Bacteria used for Acid stain
- S. aureus (blue) non acid fast - Mycobacterium smegmatis (pink) acid fast
85
- Endospore stain:
- Primary stain: Malachite green - Mordant: Steam - Decolorizer: water - Counterstain: safranin
86
- cells used for endospore stain:
- Target: endospores (green) - Non target: vegetative cells (pink)
87
- Capsule stain:
- Primary stain: Congo red - Mordant: acid alcohol (chemically fix) - Decolorizer: - Counterstain: carbol fuchsin
88
- Bacteria used for capsule stain
- Klebsiella pneumoniae in capsule stain we add color to the background and the organism remains colorless
89
- Streak plating
- Goal: to separate bacterial species into separate colonies. - We flame the loop between zones to reduce number or bacteria being dragged to next zone, resulting in isolated colony.
90
- Which bacterial type is the most/least susceptible to antiseptics?
- Least: Pseudomonas aeruginosa - Most: Mycobacterium smegmatis
91
- Which antiseptic was the most effective?
- Most: 1% formaldehyde - Least: 70% isopropyl alcohol
92
- Which bacterial type is the most/least susceptible to antibiotics?
- Most: Mycobacterium smegmatis - Least: Escherichia coli
93
- which antibiotic was the most effective?
- Most: Chloramphenicol - Least: Colistin
94
C to f:
°F = (°C x 1.8) + 32
95
Temperatures:
- Refrigerator: 4 C - Room: 25 C - Body: 37 C
96
- Selective media:
Inhibits the growth of unwanted organisms (selects what lives)
97
- Differential media:
Allows organisms to grow but the added chemicals make them look different (color change)
98
Selective and Differential - Mannitol Salt Agar
- Initial color is red - Differential for mannitol fermentation - Selects for gram +, selects against gram - (inhibits)
99
Selective and Differential - MSA results
-Positive: Yellow color - Negative: Growth but no color, stays same. Gram + options: - S. aureus: fermentor/yellow - S. epidermidis: non ferm/red.
100
Selective and differential: - EMB
- Eosin Methylene Blue. - initial color: dark purple - Selects for gram -, selects against gram +. - Differential for lactose fermentation
101
Selective and differential: - EMB results
- Strong fermenter: metallic green (Escherichia coli) - Weak fermenter: pink around the edges of colonies (Enterobacter aerogenes) - Nonfermenter: no color change, remains dark purple + growth (Proteus vulgaris)
102
Selective and differential: - MAC
- MacConkey Agar - Initial color: raspberry - Selects for Gram-, selects against Gram + - Differential for lactose fermentation.
103
Selective and differential: - MAC
- Strong fermenter: bright pink (Escherichia coli) - weak fermenter: Light pink colonies, with light brown background (Enterobacter aerogenes) - nonfermenter: Light brown plate (Proteus vulgaris)

Lab- Microbiology (2 decks)

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