Citrate Utilization Test

Question 1

Some microorganisms ferment citrate when

Answer 1

lactic acid and glucose are not available

Question 2

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

Answer 2

• 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

Question 3

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

Answer 3

Blue’
Green

Question 4

Urease Test:Identifies if a microorganism uses the enzyme

Answer 4

urease

Question 5

Urease breaks down

Answer 5

urea to produce ammonia, which is highly basic

Question 6

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

Answer 6

urease test

Question 7

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

Answer 7

Uses phenol red to determine if ammonia has been formed

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

Question 8

Determines if microorganisms are able to ferment thiosulfate

Answer 8

Hydrogen sulfide

Question 9

What does the hyrogen sulfide medium contain?

Answer 9

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

Question 10

FeSO4 combines with H2S gas to form an

Answer 10

insoluble black ferrous sulfide precipitate