Lab Final Flashcards
EMB
positive vs negative
positive: dark, opaque purple/pink colonies
negative: transparent or no growth
EMB
what changes color?
eosin
EMB
selective
differential
selects against GPs via eosin and methylene blue
differential for lactose fermenters via lactose
EMB
enzyme needed for positive
B-galactosidase
EMB
green sheen organisms
E. coli
C. freundii
K. pneumoniae
MacConkey
positive vs negative
pos: pink/red color
neg: no cc
MacConkey
what changes color?
neutral red
MacConkey
selective
differential
selects against GPs via bile salts and crystal violet
differential for lactose fermenters via lactose
MacConkey
enzyme needed for positive
B-galactosidase
TSIA
3 sugars present
least abundant
glucose (least abundant), lactose, sucrose
TSIA
results
K/K: no fermentation
K/A: glucose fermentation only
A/A: glucose, sucrose or lactose fermentation
gas pos/neg
H2S pos/neg (black)
TSIA
alkaline reversion
yellow goes back to red on slant
alkaline products of AA metabolism after glucose runs out; requires O2
2 molecules leading to H2S production
cysteine
thiosulfate
molecule that reacts with H2S to give black color
Fe(NH4)2(SO4)2 x 6H2O
TSIA
A/A organisms
E. coli
K. pneumoniae
P. vulgaris
SIM
pos/neg indole
reaction?
pos: red color after indole test with Kovac’s reagent
neg: no cc
converts tryptophan to indole
SIM
enzyme needed for pos indole
tryptophanase
SIM
indole pos organisms
E. coli
P. vulgaris
MR
sugar fermented
glucose
MR
pos/neg
pos rxn
pos: red after addition of methyl red
neg: no cc
mixed acid fermentation
MR
pos organisms
E. coli
C. freundii
M. morganii
P. vulgaris
S. enterica
S. flexneri
Citrate
pos/neg
rxn
pos: blue
neg: green
use of citric acid as sole source of carbon and energy
Citrate
what happens to pH if citrate is consumed?
indicator
goes up
bromthymol blue
Citrate
pos organisms
B. mageterium
C. freundii
K. pneumoniae
K. aerogenes
K. oxytoca
all non-fermentatives except S. paucimobilis
Citrate
enzyme needed for pos
citrase
Thiogel
pos/neg
pos rxn
pos: gelatin liquifies
neg: gelatin remains solid
hydrolysis of gelatin
Thiogel
what kind of polymer is gelatin?
protein
Thiogel
pos organisms
P. aeruginosa
P. fluorescens
Phenylalanine
pos/neg
pos rxn
pos: green color after addition of FeCl3
neg: no cc
deamination of phenylalanine