Acid potato dextrose agar
From Bugwoodwiki
Purpose
This nonselective medium works well for culturing many different fungi from aboveground tissues.
Ingredients
| Ingredient | 1 L | 500 ml |
|---|---|---|
| Distilled water | 1 L | 500 ml |
| Potato dextrose agar | 39 g | 19.5 g |
| Concentrated lactic acid 85% | 1 mL | .50 mL |
Instructions
- Mix Potato dextrose agar and distilled water
- Autoclave and cool to 50-55°C (can touch without burning fingers).
- Concentrated lactic acid while stirring.
Notes
- APDA will support the growth of many fungi, particularly fast-growing saprophytes. This makes isolations from roots, turf, and other soiled substrates difficult.
- When using this medium, it is important to carefully select tissues and disinfest them adequately. Roots and grass should be washed thoroughly under running water for several minutes. Surface disinfestation can be achieved by immersing the washed tissue in a solution of 10% bleach (1 ml Clorox and 9 ml water with a drop of Tween) for varying lengths of time dependent on the thickness of the tissue. Woody roots may require 5 minutes or more, while delicate leaf samples may need only 30 seconds to 1 or 2 minutes. Rinse specimen in sterile distilled water after disinfesting.
- Lactic acid reduces the pH of the medium to about 4.8, which is low enough to inhibit the growth of most bacteria. If lactic acid is added prior to autoclaving or to very hot medium, it can prevent solidification of the agar.
- Lactic acid may prevent or inhibit sporulation of some fungi. Growth on plain PDA may be necessary for sporulation.
References
Contributed by
From the Virginia Polytechnic Institute and State University Mediabook; Orignially created by Robert Wick; contributed by Mary Ann Hansen
Images of fungi on this Media
