Kligler Iron Agar is for presumptive tests of Yersinia enterocolitica. Peptone digest of casein and meat peptone provide nitrogen, vitamins, minerals and amino acids essential for growth. Yeast extract is a source of vitamins, particularly of the B-group. Glucose and lactose are the fermentable carbohydrates producing acid, indicated by the phenol red indicator. The color changes that result are yellow for acid production and red for alkalinization. Sodium thiosulfate is reduced to hydrogen sulfide, which reacts with the iron salt to give the black iron sulfide. Sodium thiosulfate is the H2S indicator. Ferrous sulfate provides sources of sulfates and metallic ions. Bacteriological agar is the solidifying agent. Interpretation of color changes: -Yellow: glucose-positive (fermentation of glucose). -Red or w/o changes: glucose-negative (glucose doesnt ferment). -Black: Formation of H2S. -Bubbles: Formation of gas. Slanted position: -Yellow: Lactose-positive (use of lactose). -Red or w/o change: Lactose-negative (no use of lactose).
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