Culture Media for Fungus Isolation

Culture Media for Fungus Isolation: Culture media are essential for isolation of mushroom fungi and maintaining them in a pure culture either in test tubes or in Petri plates. The fungal cultures may be grown in liquid media (broths) or on solid agar media. (Agar agar is a solidifying material obtained from sea seed weed like Geladium sp., which melts on boiling and solidifies upon cooling).

Culture Media for Fungus Isolation
Agar Media

Potato dextrose agar (PDA): Potato dextrose agar medium is very commonly used for isolation of fungus as well as for its maintenance.

Procedure: Wash 250 g potato, peel off the skin, and slice them into small pieces. Cook the sliced potato in 500 ml water for 30 minutes in an open vessel or pressure cooker for 20 minutes. Simultaneously mix 20 g agar with 500 ml of water and boil in a cooker for 30 minutes. Collect the potato extract by filter through muslin cloth or net filter. Add 20 g dextrose to the potato extract , mix thoroughly the molten agar with the potato- agar mixture and make the volume to 1 liter with distilled water.  Check the pH of the medium using pH papers. Pour the medium in to cleaned boiling tubes 15 ml / tube and plug with non-absorbent cotton wool. Arrange the tubes in a wire basket, cover it with a waste paper sheet and tie tightly with a cotton thread. Sterilize them in an autoclave or a pressure cooker at 15 lbs pressure for 20 minutes. Take out the sterilized tubes after releasing the steam and keep them in a slanting position to get agar slants. After solidifying, the tubes are arranged in a wire basket and stored in a clean room for further use.

Procedure for checking pH:  Stir the medium with a glass rod and take a small bit of  pH indicator paper and dip it in the medium. Take it out and compare the colour development with the colour chart given on the cover sheet of the filter paper book. If pH is above 7, add a few drops of 0.1N Hydrochloric acid (HCl), stir well and again check the pH for neutral. Contrastingly, if the pH of the medium is below 7, add a few drops of 0.1 N Sodium hydroxide (NaOH) to increase the pH to 7.

Culture Media for Fungus Isolation

boiling potato —> boiling agar —> mix potato extract + agar + sugar

Culture Media for Fungus Isolation

Sterilization—–>> PDA media——>>> pouring in petri plates

Some of other commonly used culture media for Fungus isolation

1) Oatmeal agar (OA)

Oatmeal 30 g
Agar agar 20 g
Distilled water 1000 ml. (pH : 7)

2) Wheat meal agar (WMA)

Wheat grain     30 g
Agar agar 30 g
Distilled water 1000 ml. (pH : 7)

3) Malt extract agar (MEA)

Malt extract     25 g
Agar agar        20 g
Distilled water 1000 ml.  (pH : 7)

4) Yeast potato dextrose agar (YPDA)

Yeast granules 1 g
Potato 200 g 
Dextrose 20 g
Agar agar 20 g 
Distilled water 1000ml (pH: 7)

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