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W.L. DIFFERENTIAL AGAR 500 grams/bottle
WL Differential Agar is a selective medium for the isolation and enumeration of microbial flora used together with WL Nutrient Agar (Cat. 1086) for the control of the manufacture of beer and other fermentation processes by yeasts. Both media are widely used in the industries of vinegar, bread yeasts, grape and wine-growing and distilled spirits. In the production of yeasts for the bakery and distillery industries, the pH of the media is adjusted to 6.5. The medium allows the selective multiplication of yeasts in fermentation liquids, which contain a microflora mix consisting of fungi and bacteria. When the number of yeasts present is relatively small, certain bacteria can also be detected. Tryptone provides nitrogen, vitamins, minerals and amino acids essential for growth. Dextrose is the fermentable carbohydrate providing carbon and energy. Yeast extract is a source of vitamins, particularly of the B-group. Monopotassium phosphate is the buffer. Potassium, Calcium and Ferric chlorides all provide essential ions for the osmotic balance. Magnesium and Manganese sulfates are sources of divalent cations. Bromocresol purple is the pH indicator. Bacteriological agar is the solidifying agent. The addition of 0.004 grams of Cycloheximide converts the WL Nutrient formula into a differential medium, which inhibits the development of yeasts and molds while permitting the notable proliferation of the bacteria present in the fermentation liquids and subsequent identification and enumeration.
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