This medium is a modification from the Kligler Agar. Sucrose ha been added to differentiate Proteus and Hafnia (sucrose positive) from Salmonella and Shigella (sucrose negative). Peptone, meat extract and yeast extract act as a source of nitrogen, sulfur, carbon, vitamine and minerals. Lactose, Sucrose and Glucose are the fermentable carbohydrates. Due to the building of acid during fermentation the pH falls. In case of oxidative decarboxylation of peptone alkaline products are builded and the pH rises. This is indicated by the phenol red, which changes its colour in acidic surroundings from red-orange to yellow, on alkalinization it turns deep red. Sodium chloride is for the osmotic balance. Gas production (CO2) is detected by the presence of cracks or bubbles in the medium, when the accumulated gas escapes