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What does TSI stand for?
Triple Sugar Iron
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When finished setting up a TSI test, what must be done?
Leave cap loose
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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.
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What enzyme is produced if organism is able to metabolize cystine
Cystine Desulferase
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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)
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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
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With TSI test they must be read within ____
24 hours
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Ingredients in TSI test
- Glucose
- Lactose&Sucrose
- Phenol Red
- Sodium thiosulfate
- Ferrous Sulfate (reacts with H2S= Black)
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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
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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
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What is the urease test used for?
To see if the urease enzyme is produce.
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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.
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What is used in a urease test?
- ~1mL of DI water1 urease tablet
- A heavy inoculation of bacteria
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A hydrolytic exoenzyme produced?
Urease
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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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