Potato dextrose agar is a common microbiological growth media often abbreviated “PDA”. It is one of the most widely used media for growing fungi.
Potato Dextrose Agar consists of potato infusion, agar and dextrose. The dextrose provides a fast easily utilized energy source and stimulant while Potato infusion provides a more complex nutrient base. Both together allow for a nutritionally balanced medium growth of most fungi. By adjusting the pH, the medium can be made to be for more accommodating to fungi while inhibiting bacteria. An antibiotic like Penicillin is also sometimes added to reduce the risk of bacterial contamination of the fungal culture.
Ingredients per liter of distilled or de-ionized water are as follows:
|Potato infusion||200 g|
|Distilled water||1 liter|
To prepare potato infusion, boil 200 g sliced, unpeeled potatoes in 1 liter distilled water for 30 min. Filter through cheesecloth, saving water, which contains the potato infusion. Mix in other ingredients and boil to dissolve.
Autoclave 15-20 min at 121°C and 15 psi. Pour 15-20 ml portions into sterile 15 × 100 mm petri dishes. The final media unless adjusted prior would be pH, 5.6 ± 0.2.
Note: Do not go over the autoclaving time of 20 minutes as it could lead to carmelisation of the dextrose. This could act as an inhibitor for mycelial growth.