Prepared Plated Media PPM

POTATO DEXTROSE AGAR

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Catalog Number : 501

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Description

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POTATO DEXTROSE AGAR is recommended by APHA and FDA for culturing yeast and molds from dairy products and foods. It can also be used in the identifi cation of fungi and yeasts in parallel with their cellular morphology, or in methods of micro cultivation in slides.This general purpose medium can be supplemented with acid or antibiotics to inhibit bacterial growth. The nutritionally rich base (potato infusion) encourages a very rich fungal and mold growth. Dextrose is the fermentable carbohydrate as a carbon and energy source. Bacteriological Agar is the solidifying agent. 

Inoculate the medium with test organisms. Incubate plates at 25 - 30°C for 18 - 48 hours. If the cultivation of Trichophyton mentagrophytes is desired, incubate up to 5 - 7 days. Yeasts will grow as cream to white colonies. Molds will grow as fuzzy colonies of various colors. To diff erentiate and isolate genus and species, carry out further Microscopic and Biochemical tests.

When the medium is to be used for the enumeration of yeasts and molds, the pH should be lowered to inhibit bacteriological growth. Add to the cooled to 45 - 50°C sterilized medium, approximately 14 ml of a sterilized 10% solution of tartaric acid to obtain a pH of 3.5. Do not reheat the adjusted medium after adding the acid because the agar may hydrolyze and not solidify.

The European Pharmacopoeia recommends in Paragraph 2.6.12 “Microbiological examination of non-sterile products: Microbial enumeration test. Preparation and use of test microorganisms”: inoculation of Aspergillus brasiliensis at 20 - 25ºC for 5 - 7 days or until good sporulation is achieved.

MICROBIOLOGICAL TEST
The following results were obtained in the performance of the medium from type cultures after incubation at a temperature of 25 - 30ºC and observed after 18 - 48 hours.