Potato Dextrose Agar (PDA) is common microbiological basal growth media made from potato infusion, and dextrose used for the growth of the fungi. PDA ( ph=5.4-5.8 ) is recommended by APHA and FDA for plate counts of yeasts and molds in the examination of foods and dairy products. It is a general purpose medium for yeasts and molds that can be supplemented with acid or antibiotics like Chloramphenicol, Tartaric Acid ( gives acidic ph <7 )and Chlortetracycline ( pH of a 10 mg/mL solution, 2.3-3.3 ) can be added as selective agents and to inhibit bacterial growth. PDA can be used for growing clinically significant yeast and molds. PDA is useful for maintaining stock cultures of certain dermatophytes.
| Ingredients* | Gms/L |
| Potatoes, infusion from | 200.0 |
| Dextrose | 20.0 |
| Agar | 15.0 |
#Final pH ( at 25°C) 5.6±0.2
Preparation of Potato Dextrose Agar (PDA)
- Suspend 39 grams in 1000 ml distilled water. Heat to boiling to dissolve the medium completely.
- Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well before dispensing.
- In specific work, when pH 3.5 is required, the medium should be acidified with sterile 10% tartaric acid.
- The amount of acid required for 100 ml. of sterile, cooled medium is approximately 1ml.
- Do not heat the medium after addition of the acid.
Appearance
Cream to yellow homogeneous free flowing powder
Gelling
Firm, comparable with 1.5% Agar gel
Colour and Clarity of prepared medium
Light amber coloured clear to slightly opalescent gel forms in Petri plates.
Cultural Response
Cultural characteristics observed after an incubation at 22 – 25°C for 4 – 5 days
Storage and Shelf Life
Store between 10-30°C in a tightly closed container and the prepared medium at 20-30°C. Use before expiry date on the label. On opening, product should be properly stored dry, after tightly capping the bottle inorder to prevent lump formation due to the hygroscopic nature of the product. Improper storage of the product may lead to lump formation. Store in dry ventilated area protected from extremes of temperature and sources of ignition. Seal the container tightly after use. Use before expiry date on the label. Product performance is best if used within stated expiry period.
Disposal
User must ensure safe disposal by autoclaving and/or incineration of used or unusable preparations of this product. Follow established laboratory procedures in disposing of infectious materials and material that comes into contact with clinical sample must be decontaminated and disposed of in accordance with current laboratory techniques
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