354 APPENDIX 



III. The same as solution I, but instead of MgC0 3 

 CaCOs is added after sterilizing. This solution stimulates 

 the simultaneous growth of both organisms, as in nature. 



Culture solutions for denitrification studies. Nitrate 

 broth or agar. Add 1 c.c. of a 1% solution of sodium or 

 potassium nitrate to tubes of ordinary broth or agar (melted), 

 mix well and re-sterilize. 



Giltay's solution. 



KH 2 PO 4 . 2.0 gms. 



MgS0 4 . . 2.0 gms. 



KNO 3 -.... 1.0 gm. 



CaCl 2 0.2 gm. 



Fe2Cle solution 2.0 drops 



Citric acid 5.0 gms. 



Method. 1. Dissolve the above substances in 800 c.c. 

 of distilled water (solution I). 



2. Add a few drops of phenolphthalein -and, using a 

 pipette, drop in just enough 10% NaOH to turn the solution 

 a faint pink. 



3. Dissolve 10 gms. dextrose in 200 c.c. of distilled water 

 (solution II). 



4. Mix solutions I and II very thoroughly. 



5. Sterilize in the autoclav at 15 Ibs. pressure for ten 

 minutes. (Lipman and Brown.) 



Giltay's agar is prepared by adding 1.5% washed agar 

 to the above solution. Boil until dissolved. Filter through 

 absorbent cotton. Sterilize in autoclav. 



Mannit solution for nitrogen-fixing organisms. 



Mannit 15.0 gms. 



K 2 HP0 4 0.2gm. 



MgSO 4 0.2gm. 



NaCl 0.2gm. 



CaSO 4 0.1 gm. 



CaC0 3 , 5.0 gms. 



10% FeCl 6 solution 1.0 drop 



