Citrate Utilization Test Flashcards

1
Q

Some microorganisms ferment citrate when

A

lactic acid and glucose are not available

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2
Q

what are the 2 enxymes that break down citrate?What do they break down and what is oxaloacetate used for ?

A
  • A citrate permease to allow citrate into the cell
    -Citrase to breakdown citrate to oxaloacetate and acetic acid
    -Oxaloacetate is further broken down to pyruvate and CO2, making the medium alkaline
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3
Q

Media containing bromthymol blue, a pH indicator, will become______when citrate is utilized. Media will stay_____if citrate is not utilized

A

Blue’
Green

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4
Q

Urease Test:Identifies if a microorganism uses the enzyme

A

urease

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5
Q

Urease breaks down

A

urea to produce ammonia, which is highly basic

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6
Q

Used to identify Proteus species because catalyze urea breakdown faster than many other species

A

urease test

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7
Q

what incicator does the urease test used. What color does it turn from and into

A

Uses phenol red to determine if ammonia has been formed

Turns PINK if solution is basic and Yellow if solution is acidic

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8
Q

Determines if microorganisms are able to ferment thiosulfate

A

Hydrogen sulfide

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9
Q

What does the hyrogen sulfide medium contain?

A

Media contains peptone and sodium thiosulfate, with FeSO4 as the H2S indicator
FeSO4 combines with H2S gas to form an insoluble black ferrous sulfide precipitate

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10
Q

FeSO4 combines with H2S gas to form an

A

insoluble black ferrous sulfide precipitate

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