BIOL 318 Midterm: TSI 59 (Triple sugar Iron agar)
4 Jul 2016
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Document Summary
Tsi agar is a differential medium used in the id of gram-negative bacilli such as the family enterobacteriaceae. Differentiate between bacteria based on their ability to ferment carbohydrates (sucrose, glucose, and lactose) and produce hydrogen sulfide and/or gas. All are sources of carbon and energy: small amt of glucose, large amt of lactose, sucrose, ph indicator. An org that ferments glucose will produce acid turning the entire medium yellow within just a few hours. After 12 hours, glucose will be exhausted. The org will then begin to break down amino acids in the medium producing ammonia and raising the ph. After 24 hours of incubation, the accumulation of ammonia will be enough to alkalinize the slant but not the butt of the tube. Therefore, org that produce a red slant and a yellow butt after 24h inc indicate the fermentation of glucose alone.
