Lab Final Flashcards

1
Q

EMB

positive vs negative

A

positive: dark, opaque purple/pink colonies

negative: transparent or no growth

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2
Q

EMB

what changes color?

A

eosin

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3
Q

EMB

selective
differential

A

selects against GPs via eosin and methylene blue

differential for lactose fermenters via lactose

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4
Q

EMB

enzyme needed for positive

A

B-galactosidase

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5
Q

EMB
green sheen organisms

A

E. coli
C. freundii
K. pneumoniae

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6
Q

MacConkey
positive vs negative

A

pos: pink/red color
neg: no cc

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7
Q

MacConkey
what changes color?

A

neutral red

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8
Q

MacConkey
selective
differential

A

selects against GPs via bile salts and crystal violet
differential for lactose fermenters via lactose

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9
Q

MacConkey
enzyme needed for positive

A

B-galactosidase

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10
Q

TSIA
3 sugars present
least abundant

A

glucose (least abundant), lactose, sucrose

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11
Q

TSIA
results

A

K/K: no fermentation
K/A: glucose fermentation only
A/A: glucose, sucrose or lactose fermentation
gas pos/neg
H2S pos/neg (black)

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12
Q

TSIA
alkaline reversion

A

yellow goes back to red on slant
alkaline products of AA metabolism after glucose runs out; requires O2

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13
Q

2 molecules leading to H2S production

A

cysteine
thiosulfate

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14
Q

molecule that reacts with H2S to give black color

A

Fe(NH4)2(SO4)2 x 6H2O

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15
Q

TSIA
A/A organisms

A

E. coli
K. pneumoniae
P. vulgaris

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16
Q

SIM
pos/neg indole
reaction?

A

pos: red color after indole test with Kovac’s reagent
neg: no cc
converts tryptophan to indole

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17
Q

SIM
enzyme needed for pos indole

A

tryptophanase

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18
Q

SIM
indole pos organisms

A

E. coli
P. vulgaris

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19
Q

MR
sugar fermented

A

glucose

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20
Q

MR
pos/neg
pos rxn

A

pos: red after addition of methyl red
neg: no cc

mixed acid fermentation

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21
Q

MR
pos organisms

A

E. coli
C. freundii
M. morganii
P. vulgaris
S. enterica
S. flexneri

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22
Q

Citrate
pos/neg
rxn

A

pos: blue
neg: green

use of citric acid as sole source of carbon and energy

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23
Q

Citrate
what happens to pH if citrate is consumed?
indicator

A

goes up
bromthymol blue

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24
Q

Citrate
pos organisms

A

B. mageterium
C. freundii
K. pneumoniae
K. aerogenes
K. oxytoca
all non-fermentatives except S. paucimobilis

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25
Q

Citrate
enzyme needed for pos

A

citrase

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26
Q

Thiogel
pos/neg
pos rxn

A

pos: gelatin liquifies
neg: gelatin remains solid

hydrolysis of gelatin

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27
Q

Thiogel
what kind of polymer is gelatin?

A

protein

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28
Q

Thiogel
pos organisms

A

P. aeruginosa
P. fluorescens

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29
Q

Phenylalanine
pos/neg
pos rxn

A

pos: green color after addition of FeCl3
neg: no cc

deamination of phenylalanine

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30
Q

Phenylalanine
what does reagent detect?

A

phenylpyruvic acid

31
Q

Phenylalanine
enzyme needed for pos

A

deaminase

32
Q

Phenylalanine
pos organisms

A

M. morganii
P. vulgaris

33
Q

Nitrate
pos/neg

A

pos: N2 gas in tube; red color after A & B regents; no cc after zinc
neg: red after zinc

34
Q

Nitrate
end product if red after A & B

A

NO2 -
nitrite

35
Q

Nitrate
negative indicates…

A

no reduction of nitrate

36
Q

Nitrate
end product if no cc after zinc

A

NH3 or R-NH2

37
Q

Nitrate
enzyme needed for pos

A

nitratase/nitrate reductase

38
Q

Nitrate
N2 organisms
neg organisms

A

N2: P. aeruginosa; P. stutzeri
neg: A. calcoaceticus; A. faecalis; S. paucimobilis

39
Q

Urease
pos/neg
pos rxn

A

pos: bright pink
neg: no cc
hydrolysis of urea

40
Q

Urease
end products of urea hydrolysis

A

CO2 and ammonia

41
Q

Urease
what causes cc?

A

phenol red
pH rises

42
Q

Urease
pos organisms

A

M. morganii
P. vulgaris

43
Q

VP
pos/neg
pos rxn

A

pos: red after VP A and B
neg: no cc

organism produces acetylmethyl carbinol from glucose fermentation

44
Q

VP
pos organisms

A

S. marcescens
Enterobacter aerogenes

45
Q

Starch
pos/neg
pos rxn

A

pos: clearing around colonies after Lugol’s iodine
neg: no clearing

starch hydrolysis

46
Q

Starch
enzyme needed for pos

A

a-amylase
oligo-1,6-glucosidase

47
Q

Starch
pos organisms

A

B. cereus
B. subtilis
B. mageterium

48
Q

Starch
iodine reacts with starch to form…

A

dark brown color

49
Q

Litmus milk
5 things it can tell us

A
  1. litmus reduction
  2. clotting of casein
  3. digestion of casein
  4. acid from lactose ferm
  5. gas
50
Q

Litmus milk
pH indicator

A

litmus

51
Q

litmus milk
white result

A

litmus reduction due to anaerobic respiration

52
Q

Litmus milk
pink result

A

acid; lactose fermentation

53
Q

Litmus milk
clear fluid in top of curd

A

whey

54
Q

Litmus milk
curd result

A

stormy fermentation

55
Q

Litmus milk
pos organisms

A

B. cereus (curd)
L. acidophilus (pink, curd)

56
Q

Litmus milk
blue result

A

proteolysis giving ammonia
alkaline

57
Q

Litmus milk
—– converts casein to paracasein, soft curd

A

renin

58
Q

Litmus milk
clearing of media result

A

proteolysis

59
Q

OF
test ingredients

A

tryptone
bromothymol blue
a sugar

60
Q

OF
procedure with 2 tubes

A

one left open to air
one covered with mineral oil

61
Q

OF
results

A
62
Q

OF
example organisms

A

fermenter (both yellow): E. coli
oxidizer (yellow only in open tube): Pseudomonas
non-saccharolytic (both green): Alcaligenes

63
Q

are lactose fermenters typically pathogenic or non-pathogenic?

A

tend to be found in gut microbiome
generally not pathogenic but can be opportunistic pathogens

64
Q

arginine dihydrolase intermediate

A

agmantine

65
Q

VP intermediate

A

acetoin

66
Q

decarboxylase intermediate

A

cadaverine

67
Q

phenylalanine intermediate

A

phenylpyruvic acid

68
Q

gelatinase intermediate

A

oligopeptide

69
Q

citrate slant intermediate

A

oxaloacetate

70
Q

ONPG test is required for Neisseria because…

A

does not produce fermentation acid

71
Q

Loeffler slant iron

A

absence of iron prevents DtxR from binding tox operator

72
Q

VJ is to MSA as…

A

Salmonella-Shigella is to MacConkey

73
Q

Hektoen tests for ferm of which sugar?

A

lactose

74
Q

Ox + = facultative anaerobe

A

false