# 12: SOIL EXTRACT MEDIUM ## Main sol. 12 400 g air-dried garden soil 1000 ml Tap water 15 g Agar 1. Sterilize 400.0 g of air-dried garden soil (with high content of organic matter) in 1000 ml tap water for one hour at 121°C. Allow it to sediment for a few hours at room temperature. Centrifuge the supernatant. Add 15.0 g agar per 1000 ml to the clear supernatant solution thus obtained. Adjust pH to 6.8 - 7.0 and sterilize.