TRIPLE SUGAR IRON AGAR SLANT (10 Slants)

Triple Sugar Iron Agar Slant is a differential medium used for identification of Gram-negative enteric bacilli, based on their ability to ferment carbohydrates, production of gas and hydrogen sulphide (H₂S) formation. It is a medium incubated for rapid screening of the quality of egg, meat, food, milk and milk products, suitable for limit test for microbes and confirmation for Salmonella and is the medium suggested by APHA based on the works of Sulkin and Willett that was modified by Hajna.
The casein enzymic hydrolysate, animal tissue peptic digest, yeast extract and beef extract present in the preparation supply nitrogenous matter, sulphur, trace elements, vitamins and other nutrients. Lactose, sucrose and dextrose are the fermentable carbohydrates and phenol red is the pH indicator that detects acid production by changing color from orange red to yellow. Sodium thiosulfate and ferrous ions constitute the H₂S detection system. Hydrogen sulphide production gives a distinctive black precipitate, which is usually seen in the butt.
The slant-and-butt is used to differentiate various types of fermentation reactions. A red slant and yellow butt indicates glucose fermentation without lactose or sucrose fermentation, while a yellow slant and yellow butt indicates fermentation of lactose and/or sucrose along with glucose. Gas production is observed as bubbles or cracks in the agar.

Differentiates Gram-negative enteric bacilli through glucose, lactose, and sucrose fermentation, with additional detection of gas and hydrogen sulphide production.