DG18 Agar (ISO) - Dichloran (18%) Glycerol Agar

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Application(s): Industrial, Food
Organism(s): Yeast & Mould

Lab M´s Dichloran 18% Glycerol Agar (DG18 Agar) is a medium for the enumeration of osmophilic yeasts and xerophilic moulds in food and animal products.

DG18 Agar is used for the enumeration of viable osmophilic yeasts and xerophilic moulds in food or animal feed products with a water activity of less than or equal to 0.95 by a colony count technique. This includes such foods as dry fruits, jams, cakes, dried meat, salted fish, grains, cereals, flours, nuts, spices, condiments and some animal feeds. This medium is not suitable for the examination of dehydrated products with a water activity of less than or equal to 0.60 and does not allow the enumeration of mould spores or the detection of halophilic xerophilic fungi found in dried fish.

The reduction in water activity in this medium is achieved by the addition of glycerol at approximately 18% and this is very important as many yeast and moulds actually require a low water activity to enhance growth and colony development. The medium also contains the antifungal agent dichloran, which restricts the spreading of mucoraceous fungi and restricts the colony size of other genera making colony counting an easier task.

Additional selectivity against bacterial growth is achieved by the incorporation of the heat-stable antibiotic Chloramphenicol. Glucose is incorporated as the fermentable carbohydrate source, with casein enzymatic digest providing the essential vitamins, minerals, amino acids, nitrogen and carbon.

Prepared according to ISO 21527-2:2008, this medium is based on the original formulation described by Hocking and Pitt (1980), and is also compliant with methods stated in the Bacteriological Analytical Manual (BAM).