I06 SOIL BACTERIOLOGY 



up in dishes, and add enough culture-media to half cover 

 blocks. 



5. Inoculate the surface of blocks and jncubate at 25"^ 

 to 30° C. 



DENITRIFICATION 



Medium 33 

 Solution for Nitrate .Reduction 



(a) Potassium nitrate (KNO3) i gm. 



Asparagin (C4H8N2O3 + H2O) i gm. 



Water 250 ex. 



(6) Citric acid (CeHgO? + H2O) 5.0 gm. 



or Neutral sodium citrate 8.5 gm. 



' Monobasic potassium phosphate (KH2PO4) i.o gm. 



Magnesium sulphate (MgS04 + 7H2O) i.o gm. 



Calcium chlorid (CaCl2 + 6 H2O) 0.2 gm. 



Ferric chlorid (FeCls + 6H2O) trace 



Distilled water 250.0 ex. 



Neutralize the citric acid solution with a 10 per cent, 

 solution of sodium or potassium hydroxid, using phenol- 

 phthalein as an indicator. Mix the two solutions, cool to 

 15° C, and add sufl&cient water to make i liter. If the 

 asparagin and potassium nitrate are dissolved along with 

 the other salts, a decomposition may occur. This is marked 

 by a browning of the liquid due to the presence of nitrous 

 acid. 

 For a solid medium add 15 grams of agar to i liter. 



Medium 34 

 Nitrate Bouillon 



Potassium nitrate (KNO3) , 5 gm. 



Bouillon 1000 c.c. 



