Microbiology Lab: KIA/TSI Test 31 Questions with Verified Answers
What five things are being tested in a KIA/TSI test? - CORRECT ANSWER 1. Glucose
... [Show More] fermentation
2. Lactose fermentation
3. Sulfur reduction
4. Gas production
5. Amino acid degeneration
What happens to the color of the tube when glucose is fermented? - CORRECT ANSWER The sugar is fermented and acid drops the pH, this causes the tube to turn yellow
When the butt of the slant is yellow but the rest of the slant is pink, what does this mean? - CORRECT ANSWER It means that glucose was used and then the bacteria switched to breaking down amino acids when glucose was no longer available
In lactose fermentation when the sugar is fermented what happens to the pH in the tube? - CORRECT ANSWER The pH in the tube drops and the tube turns yellow
When the tube turns yellow in a KIA test what is it fermenting? - CORRECT ANSWER Glucose and/or lactose
How can you tell if only glucose or lactose is being fermented? - CORRECT ANSWER If there is any pink in the slant then only glucose is being fermented. If there is pink it means the bacteria started breaking down amino acids.
When sulfur is being reduced what color does the tube turn? - CORRECT ANSWER Black
What is sulfur reduced to? - CORRECT ANSWER H2S
What combination of two thing cause the black color in the tube? - CORRECT ANSWER H2S and iron
T/F Sulfur reduction can only take place in acidic conditions? - CORRECT ANSWER True
How can you tell if there was gas production in a KIA slant? - CORRECT ANSWER If there is lifting or cracking in the agar
T/F If lifting has occurred in a KIA slant, that means that there was no gas production? - CORRECT ANSWER False
What happens in amino acid degeneration? - CORRECT ANSWER The sugar has run out or the bacteria cannot ferment that sugar, this causes the breaking down of amino acids into NH3
When NH3 is produced due to amino acids being broken down what happens to the color of the tube and the pH? - CORRECT ANSWER The tube turns pink and the pH rises
What causes the pink color in the tube? - CORRECT ANSWER When amino acids begin to break down NH3 it causes the pH to rise which causes the color change
How are KIA slants inoculated? - CORRECT ANSWER Stab and streak
Enteric bacteria - CORRECT ANSWER The TSI test is used in the identification of ___ which metabolize the triple sugars and release H2S.
Lactose, sucrose, and glucose - CORRECT ANSWER What does TSI agar contain?
streaking the slant, stabbing the agar - CORRECT ANSWER How are TSI slants inoculated?
Orange - CORRECT ANSWER What color is the agar prior to inoculation?
Yellow butt and red slant - CORRECT ANSWER Glucose fermentation is seen as ____ due to the fact that glucose is in low concentration and acid accumulates at the bottom. At the surface, in the presence of oxygen, the slant remains alkaline.
lactose and/or sucrose fermentation, acidification of the whole medium - CORRECT ANSWER What does a yellow butt and slant indicate?
Gas formation - CORRECT ANSWER ___ seen as splitting of the agar.
H2S - CORRECT ANSWER ___ is seen as blackening of the agar
identify and differentiate among enterics based on sugar fermentation and H2S gas production - CORRECT ANSWER What is the purpose of TSI agar test?
The organisms ferment glucose - CORRECT ANSWER What does a yellow butt and unchanged color in the slant indicate?
Ferrous ammonium sulfate - CORRECT ANSWER The breakdown of ____ results in the release of ferrous iron compounds, which will precipitate forming a black sediment
phenol red - CORRECT ANSWER ___ is the pH indicator and is used to monitor acid production from carbohydrate fermentation.
lactose and sucrose - CORRECT ANSWER What is in high concentration?
glucose - CORRECT ANSWER What is in low concentration?
18-24 hours - CORRECT ANSWER The test should be read ___ post inoculation because acid products can be further metabolized resulting in alkalinization of the medium. [Show Less]