Triple sugar iron agar results interpretation

Background
Experiment 2: TSI The triple sugar iron agar (TSI) can identify gram negative bacteria based on how they metabolize carbohydrates. It contains three carbohydrates-glucose, lactose and sucrose, in addition to sodium
Background continued...
thiosulfate which some bacteria use in the production of hydrogen sulfide (H2S). It also contains iron in the ferrous form and phenol red as a pH indicator. TSI is poured into a tube when heated to a liquid form, and the tube is slanted as it cools and hardens. When inoculated, a needle transfers microbes down into the tube and also streaked on the slant of the agar surface Glucose is in a smaller quantity than lactose or sucrose and is metabolized first by bacteria. Acids are produced by this metabolism, and the medium changes from red to yellow. As glucose becomes unavailable as it is used up, the surface of the slant will revert back to red if the bacteria cant metabolize lactose or sucrose. This slant would be described as K/A -the slant is red (K or alkaline) and the deep is yellow (A or acidic). If an organism can metabolize all three sugars, the acids produced turn the agar surface yellow and t deep yellow which is described as A/A. Other observations which may be visualized in this agar are the production of gas by bacteria, seen cracks and gaps in the agar, and the production of hydrogen sulfide which appears as a black precipitate in the deep of the tube. All of these metabolic changes are indicative of particular bacte pecies of gram negative bacilli.
Questions
1. Why is the TSI test done? 2. What does TSI stand for? What are the three carbohydrates present in the media? 3. What is the pH indicator in the TSI tube? 4. What do an alkaline slant and an acid deep indicate (K/A)? 5. What do an acid slant and an acid deep indicate (A/A)? 6. What do an alkaline slant and an alkaline deep indicate (K/K)? 7. Why would there be bubbles or breaks in the agar? 8. What does a black color in the media indicate?
Experiment 2: TSI The triple sugar iron agar (TSI) can identify gram negative bacteria based on how they metabolize carbohydrates. It contains three carbohydrates-glucose, lactose and sucrose, in addition to sodium
thiosulfate which some bacteria use in the production of hydrogen sulfide (H2S). It also contains iron in the ferrous form and phenol red as a pH indicator. TSI is poured into a tube when heated to a liquid form, and the tube is slanted as it cools and hardens. When inoculated, a needle transfers microbes down into the tube and also streaked on the slant of the agar surface Glucose is in a smaller quantity than lactose or sucrose and is metabolized first by bacteria. Acids are produced by this metabolism, and the medium changes from red to yellow. As glucose becomes unavailable as it is used up, the surface of the slant will revert back to red if the bacteria can't metabolize lactose or sucrose. This slant would be described as K/A -the slant is red (K or alkaline) and the deep is yellow (A or acidic). If an organism can metabolize all three sugars, the acids produced turn the agar surface yellow and t deep yellow which is described as A/A. Other observations which may be visualized in this agar are the production of gas by bacteria, seen cracks and gaps in the agar, and the production of hydrogen sulfide which appears as a black precipitate in the deep of the tube. All of these metabolic changes are indicative of particular bacte pecies of gram negative bacilli.
1. Why is the TSI test done? 2. What does TSI stand for? What are the three carbohydrates present in the media? 3. What is the pH indicator in the TSI tube? 4. What do an alkaline slant and an acid deep indicate (K/A)? 5. What do an acid slant and an acid deep indicate (A/A)? 6. What do an alkaline slant and an alkaline deep indicate (K/K)? 7. Why would there be bubbles or breaks in the agar? 8. What does a black color in the media indicate?