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What does TSI stand for?
Triple Sugar Iron
When finished setting up a TSI test, what must be done?
Leave cap loose
What does the TSI test for?
- To test is to see if the amino acid cystine can be metabolized. (only works in acidic environments)
- If organism can metabolize glucose, lactose, sucrose or All of the above.
What enzyme is produced if organism is able to metabolize cystine
List the order in which Cystine Desulferase works, and what test is used to determine its presence.
- Cystine Desulferase breaks cystine into pyruvate
- Produces a hydrogen sulfide gas (rotten eggs)
What does it mean if a TSI test is black?
- A black TSI result means its positive for breakdown of cystine ALSO positive for creating Hydrogen sulfide
- (H2S + ferric sulfide)= black ppt
With TSI test they must be read within ____
Ingredients in TSI test
- Phenol Red
- Sodium thiosulfate
- Ferrous Sulfate (reacts with H2S= Black)
What do the colors in this test mean? How would you write the results?
- A. A/A, Glucose and lactose/sucrose fermentation. Hydogen gas (+) gas (+)
- B. K/A, Glucose only fermentation. Hydrogen sulfide (-) gas (-)
- C. K/A, Glucose only fermentation. Hydrogen sulfide (+) gas(-)
- D. No Fermentation. Peptone is catabolized.
- Yellow=Acidic (A)
- Red= Alkaline (K)
- Black= H2S (+) Hydrogen sulfide gas
What is reversion, what does it mean?
- Reversion is when the slant of a TSI turns yellow(acidic), but then to red(alkaline).
- This means the organism is a glucose only fermenter.
- I uses all the glucose then on to other sources of beef extract/peptone -> NH3 -> back to basic
What is the urease test used for?
To see if the urease enzyme is produce.
What does urease do?
- It breaks down urea (found in urine and stomach juices) into a nitrogen based cmpd NH3NH3(ammonia) raises to an alkaline pH level.
What is used in a urease test?
- ~1mL of DI water1 urease tablet
- A heavy inoculation of bacteria
A hydrolytic exoenzyme produced?
What test is this? How would you read it?
- This is a urease test, testing to see if a bacteria can break down urea into ammonia (NH3)
- Yellow tests A&B are (-) for urea hydrolysis and are acidic.
- Test C is neutral
- Test B is (+) for urea hydrolysis, creating NH3, and is alkaline
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