However, it is not hard to make a simple and effective version from scratch at little cost.
Things You Will Need
Preparing Potato Extract
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Place potatoes in a saucepan with approximately 1.2 liters of tap water and boil on a stove for 1 hour.
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Remove saucepan from heat and let liquid cool until it can be comfortably handled (about 10 minutes).
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Pour liquid potato extract through a strainer or cheesecloth and collect it in another container.
Preparing the Medium
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Add dextrose and agar to 1 liter of the potato extract water.
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Test the pH of the solution with pH test paper or a pH meter.
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If the pH is above 6.5, adjust it down by adding one drop of the hydrochloric acid solution at a time and retesting.
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If the pH is below 6, adjust it up by adding one drop of the sodium hydroxide solution at a time and retesting.
Sterilization
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Thoroughly mix the medium and divide it into smaller batches of 250 mL poured into the four 500-mL flasks (Note: each flask must be no more than half full to avoid boil over).
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Cover each flask with a piece of loosely crimped aluminum foil, so the foil will not fall off, but does not make a tight seal.
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Place the flasks in a pressure cooker.
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Operate the pressure cooker in accordance with the manufacturer's instructions to sterilize the PDA at 121 degrees C (250 degrees F) at a pressure of 103,421 Pascals(15 PSI) for 15 minutes.
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Shut off the pressure cooker and let it return to atmospheric pressure, then remove the flasks and let them cool until they can be handled.
Pouring the Medium
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Line up the sterile petri dishes on a flat surface.
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Once the flasks have cooled to handling temperature, but before the medium begins to solidify, grasp a flask with one hand and remove and set aside its foil lid with the other hand.
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For each petri dish, lift the lid with one hand, quickly fill halfway with liquid PDA, and replace the lid.
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Repeat Step 3 above until all petri dished are filled.
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If there is any PDA left over, loosely recover the flask with its original foil lid, let it cool and solidify, tighten the foil lid and store in a refrigerator.
The Drip Cap
- Potato dextrose agar (PDA) is a good general-purpose semisolid medium used for culturing fungi.
- It is often used to isolate, grow and maintain mushroom-forming species.
- Pour liquid potato extract through a strainer or cheesecloth and collect it in another container.
- If the pH is above 6.5, adjust it down by adding one drop of the hydrochloric acid solution at a time and retesting.
- Once the flasks have cooled to handling temperature, but before the medium begins to solidify, grasp a flask with one hand and remove and set aside its foil lid with the other hand.