Objective 2 : To prepare Potato dextrose agar (PDA) for preparation of mushroom culture
Composition :
Potato 250 g
Dextrose 20 g
Agar 20 g
Distilled water 1000 ml.
Materials required : Boiling vessel, burner, glass rod, muslin cloth, beaker, measuring cylinder,
conical flasks, test tubes, pH papers, non-absorbent cotton.
Procedure :
1. Peel and wash 250 g potato and slice them into small pieces.
2. Cook the sliced potato in 500 ml. distilled water for 30 minutes in a boiling vessel.
3. Simultaneously mix 20 g agar and 20 g dextrose with 500 ml. of distilled water.
4. Collect the potato extract by filter through muslin cloth.
5. Mix thoroughly the molten agar with the potato- agar mixture and make the volume to 1 litre
with distilled water.
6. Check the pH of the medium using pH papers. (pH – 6-6.5)
7. Pour the medium in to clean conical flask and test tubes and plug with non- absorbent cotton.
8. Sterilize them in an autoclave or a pressure cooker at 15 lbs pressure for 20 minutes.
9. Take out the sterilized tubes after releasing the steam and keep them in a slanting position to
get agar slants.
10. After solidifying, the tubes and conical flasks are stored in a clean room for further use.
