Dichloran Glycerol Agar (DG 18) is a selective medium based on the formulation of Hocking and Pitt. It is recommended for the enumeration and isolation of xerophilic molds from dried and semi-dried foods, such as fruits, spices, cereals, nuts, meat and fish products. Glycerol reduces the water activity from 0.999 to 0.95, thereby reducing bacterial growth, and is also the carbon source. Chloramphenicol is an antibiotic which aids in isolating pathogenic fungi from heavily contaminated material, as it inhibits most contaminating bacteria. It is a recommended antibiotic for use with media due to its heat stability and wide bacterial spectrum. Bacteria growth inhibition and spreading of more-rapidly growing molds restriction aids in the isolation of slow-growing fungi by preventing their overgrowth by more-rapidly growing species. Dichloran prevents the fast spreading of mucoraceous fungi, improving the colony count. Peptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Dextrose is the fermentable carbohydrate providing carbon and energy. Potassium phosphate acts as a buffer system. Magnesium sulfate provides sulfur and other trace elements. Bacteriological agar isthe solidifying agent.
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