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21 Cards in this Set
- Front
- Back
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Why do you need to filter sterilize the carbohydrates used in the carb fermentation test?
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disaccharides or polysaccarides will split if heated
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What ingredients are included in the media for the CFT?
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peptone, NaCL, pH indicator (phenol red or acid fushion), a durham tube may be included, filtered sterilized carbs at 1%
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What would be a pos and neg reaction in the CFT?
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pos = yellow, neg=red
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Why must the MR test be incubated 48 hrs?
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because if you do test to early you could be detecting the pyruvic acid produced
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Enterobacteriaceae will either metabolize glucose by the ___ ______ _____ and be ___ or the ____ _____ ______ and be ______
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mixed acid pathway, MR+, butylene glycol pathway, VP+
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What organisms are VP +
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enterobacter, klebsiella, serratia
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what two enzymes does an organism require in order to demonstrate lactose fermentation?
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B-galactosidase permease and B- galactosidase
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what does B-galactosidase permease and b-galactosidase do?
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B-GP allows lactose to penetrate the cell wall
B-G - inside the cell, this hydrolyzes lactose into glucose and galactose |
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What 3 categories do enterobacteriaceae fall into?
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1. possess both enzymes (rapid lactose fermenter (LF on MAC)
2. lack permease enzyme (NLF at 24hrs) 3. lack both enzymes - true NLF |
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What separates late lactose fermenters from NLF?
Give an example of a LLF |
ONPG - Shigella Gastro
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If an organism has the enzyme B-D-galactosidase what colour will the ONPG turn proving positive, what product causes this?
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it will produce o-nitrophenol which produces a yellow colour
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What are the ingredients of TSI
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peptone, NaCL, glucose 0.1%, lactose 1%, sucrose 1% and phenol red
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What 2 ingredients of TSI show presence of H2S
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sodium thiosulphate, ferrous sulphate which prodces hydrogen sulfide gas
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Whats the purpose of indole
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determine organisms ability to decompose tryptophan to produce indole *tryptophanase
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what reagent reacts with indole to produce pink colour
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paradimethylaminobenzaldehyde, kovacs reagent
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in simmons citrate test what does the sodium citrate provide
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carbon
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what causes the alkalinity of the slant in simmons citrate. what is the reagent that changes colour?
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concomitant breakdown of the ammonium salts to ammonia. bromthymol blue
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What products are formed when urea is broken down?
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co2 and NH3
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what reagent is in urease test? what colour is pos
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phenol red - pinky colour detecting alkalinity of NH3
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What does the Nitrate reductase test show?
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determines the org ability to reduce nitrite.
nitrate - nitrite - nitrogen gas |
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What reagents are used in the nitrate reductase test? why
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sulfanilic acid and alpha napthylamine
if colour formed then reduced to nitrate, if no colour formed add zinc dust.. no colour change is reduced to nitrogen gas, colour change = neg no enzymes present |
