A recipe for preparing PDA from scratch

Potato Dextrose Agar (PDA) is a commonly used medium for growing fungi and bacteria. Here is a recipe for preparing PDA from scratch:


200 g of potatoes
20 g of dextrose
15 g of agar
1000 ml of distilled water


1) Rinse the potatoes and peel them. Cut the potatoes into small pieces.
2) Boil the potato pieces in 1000 ml of distilled water for 20 minutes or until they are soft.
3) Strain the potato pieces from the water and reserve the liquid.
4) Weigh out 20 g of dextrose and add it to the potato liquid. (or Glucose powder)
5) Weigh out 15 g of agar and add it to the potato liquid.
6) Place the mixture in a Erlenmeyer flask and sterilise in an autoclave for 45 minutes.
7) In the sterile airflow of a laminar flow hood, transfer the PDA media into the PE disposable Petri dishes. Fill each dish to approximately 1/3 of its capacity. Gently tap the dishes to distribute the media evenly and eliminate air bubbles. Leave to cool completely in the sterile airflow until the media has solidified.

Storage of Petri Dishes:

After the media has solidified, place the dishes in a sterile zip lock bag. Store the dishes in a cool, dark location.

Note: Sterile techniques must be followed at all times during handling of the media and Petri dishes to prevent contamination.

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