16 PRINCIPLES OF SOIL MICROBIOLOGY 



II. Lipman and Brown's synthetic agar: 



Distilled water 1000 cc. Glucose 10 grams 



Agar 20 grams MgS0 4 -7H 2 0.20 gram 



Peptone 0.05 gram K 2 HP0 4 0.50 gram 



III. Albumin agar: 



Distilled water 1000 cc. MgS0 4 -7H 2 0.20 gram 



Agar 15.00 grams K 2 HP0 4 0.50 gram 



Powdered egg al- Fe 2 (S0 4 ) 3 trace 



bumin 0.25 gram 



Glucose 1.00 gram 



The albumin is suspended in 5 to 10 cc. of water, then 1.0 cc. of 0.12V NaOH 

 solution is added, so as to convert it into sodium albuminate; the albuminate is 

 added only to the filtered medium. 



IV. Casein agar. Same as medium III, only 1.0 gram of purified casein is 

 used in place of the albumin. The casein is dissolved in 8 cc. of 0.12V NaOH. 



V. Asparaginate agar: 



Distilled water 1000 cc. NH 4 H 2 P0 4 1.5 grams 



Agar 12.0 grams CaCl 2 0.1 gram 



Sodium asparaginate. 1.0 gram KC1 0.1 gram 



Glucose l.Ogram FeCl 3 trace 



MgS0 4 -7H 2 0.2 gram 



10 cc. of 1.02V NaOH solution added per liter to bring the desired reaction. 



VI. Asparagine-mannite agar: 



Distilled water 1000 cc. NaCl 0.1 gram 



Agar 15 grams FeCl 3 0.002 gram 



K2HPO4 l.Ogram KN0 3 0.5 gram 



MgS0 4 -7H 2 0.2 gram Asparagine 0.5 gram 



CaCl 2 0.1 gram Mannite l.Ogram 



The mannite is added after the agar and other constituents have been dis- 

 solved and medium filtered. The reaction is adjusted to pH 7.4. 



VII. Urea ammonium nitrate agar: 



Distilled water 1000 cc. Glucose 10.0 grams 



Agar 15.0 grams Urea 0.05 gram 



K 2 HP0 4 0.5 gram Ammonium nitrate. . . 0.1 gram 



MgS0 4 -7H 2 0.2gram Fe 2 (S0 4 ) 3 trace 



Reaction is about pH 7.0. 



In addition to these media, soil extract and tap water gelatin recommended 

 by Conn and used chiefly for qualitative purposes can also be mentioned: 



VIII. Tap water gelatin 29 



Tap water 1000 cc. 



Gelatin (Gold Label) 200 grams 



These media are about equally favorable to the development of 

 aerobic, heterotrophic bacteria, deriving their nitrogen from inorganic 



19 Medium is clarified by means of white of egg; reaction is adjusted to 0.5 per 

 cent normal acid to phenolphthalein, which requires 20-30 cc. 1.0 N NaOH; when 

 Bacto-gelatin is used, only 10 oc. of alkali is required and no clarification. 



