66. MEDIUM WITH SOIL EXTRACT

Peptone 5.0 g

Beef extract 3.0 g

Agar 15.0 g

Soil extract 250.0 ml

Tap water 750.0 ml

pH 7.0

Autoclave at 121°C for 15 min.

Preparation of soil extract: dry garden soil, rich in organic material, in the air by spreading in a thin layer, comminuting and stirring. Then sieve through a rough sieve, and mix 400 g of soil with 960 ml of tap water. Autoclave at 121°C for 1 hour at the end of the day but leave the autoclave open over night. Filter the cooled extract through filter paper, autoclave 300 ml of filtrate at 121°C for 20 min and allow to stay for 2 weeks or longer to settle the sediment. Decant the clear supernatant liquid and use to prepare the medium.