For the differentiation of Gram negative Enterobacteria
محیط کشت میکروبیولوژی Dehydrated Culture Media از کمپانی Condalab
Kligler Iron Agar may be used to differentiate Gram-negative Enterobacteria on the basis of carbohydrate fermentation and H2S production. The Peptone mixture provides nitrogen, vitamins, minerals and amino acids essential for growth. Sodium chloride supplies essential electrolytes for transport and osmotic balance. Dextrose 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 sulfide and Ferric ammonium citrate are H2S indicators. Bacteriological agar is the solidifying agent. Lactose non fermenters (e.g.,Salmonella and Shigella) initially produce a yellow slant due to acid formation caused by the fermentation of dextrose. Once the dextrose supply runs out in the aerobic environment of the slant, the reaction reverts to alkaline (red slant) due to oxidation of the acids. The reversion does not occur in the anaerobic environment in the butt, which remains acid (yellow butt). Lactose fermenters produce yellow slants and butts due to the fact that sufficient acid is produced in the slant to maintain an acid pH under aerobic conditions. Organisms incapable of fermenting the carbohydrates produce red slants and butts. For best results, Kligler Iron Agar should be used on the day of preparation or melted and solidified before use.