XLT4 Agar Base
XLT4 Agar is used for the isolation of non-typhi Salmonella spp. This medium is predominantly effective when used with samples where overgrowth of contaminating flora is anticipated. In order to inhibit the growth of non-Salmonella organisms, the medium is supplemented with Tergitol 4. Meat Peptone and Yeast Extract provide nitrogenous sources for the optimal growth of Salmonella spp. Xylose, Lactose, and Sucrose are the main fermentable carbohydrates. Upon their utilization, the pH indicator Phenol Red shifts from red to yellow. Thiosulfate and Ferric Ammonium Citrate detect hydrogen sulfide production in alkaline conditions by the formation of a black precipitate. Sodium Carbonate stabilizes the pH and Sodium Chloride maintains the osmotic equilibrium.