Oxytetra Glucose Yeast Agar Base w/ Biotin were originally formulated by Mossel et al for the isolation and enumeration of yeasts and moulds from foodstuffs. Mossel et al further added Oxytetracycline as a selective agent and found that the use of Oxytetracycline in a medium with a neutral pH gives increased counts of yeasts and molds as compared to media having a low pH to suppress bacterial growth.
Yeast extract provides essential growth nutrients. Dextrose acts as carbon and energy source. Oxytetracycline makes the medium more selective by inhibiting the growth of Lactobacilli encountered in milk and milk-products at low pH. Biotin is used as a vital growth factor for lactose utilizing yeast.
The choice of a suitable media for enumeration of yeasts and moulds greatly depends on the nature of food stuffs to be tested and the organisms that grow on them. These media remain bacteriostatic when inoculated with not greater than 1 ml of a 10-1 food dilution and incubation at 22°C (2). The number of yeasts or molds is calculated per one gram or 1 ml of sample under investigation by multiplying the number of colonies with the dilution factor. Lactic acid bacteria are inhibited on this medium.
Storage and Shelf-life:
Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.