Talk:TSI

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I removed the following

TSI test is a determinitive test used when dealing with Gram neg. Rods. TSI stands for triple sugar iron, and is in the form of a test tube, with a slant agar. The three sugars used in a TSI test are lactose, glucose and sucrose. The concentrations of these sugars are; lactose 1%, Sucrose 1%, Glucose .1%. The concentration difference is what enables you to differentiate between which saccharide is being digested. Phenyl red is the indicator used in determining carbohydrate fermentation. When a bacteria breaks down the carbohydrate and acid by product is produced, resulting in an increased acidity of the solution. Phenyl red when in a ph of 7 or higher is red, pink at 8 or higher. However when the ph drops below 6.8 phenyl red turns yellow. The TSI tube is read by first looking at the slant to see if lactose was fermented, yellow indicating it was, then second by looking at the butt of the test tube to see if glucose was fermented, once again yellow indicates positive fermentation. Secondary tests involved in the TSI include the formation of gas, little bubbles in the agar, or Hydrogen Sulfide H2S, which is indicated by a black precipitate at the bottom of the tube. As a rule of thumb, if H2S is produced one can always deduce that glucose fermentation has occurred as well, since the black bottom might inhibit you from determining if Glucose was fermented (yellow bottom).

If it's really relevant it should be edited and moved to something like TSI (test) Matteo (talk @) 19:59, 12 April 2007 (UTC)