Azotobacter medium

For the isolation of Azotobacter, Azomonas, and Azorhizophilus

Recipe:

1. Prepare carbon source solutions
2. Add 990 ml DI-H~2~O to 2L flask or bottle
3. Add the following components to the DI-H~2~O:
   • 0.1 g CaCl2 x 2 H2O
   • 0.1 g MgSO4 x 7 H2O
   • 5 mg Na2MoO4 x 2 H2O
   • 0.9 g K2HPO4
   • 0.1 g KH2PO4
   • 0.01 g FeSO4 x 7 H2O
   • 5 g CaCO3
   • 10 g Agar
4. Adjust pH to 7.3.
5. Autoclave
6. Allow to cool to ~ 55^o^C
7. Add 2.5 ml glucose solution
8. Add 2.5 ml mannitol solution
9. Mix gently, but throughly
10. Pour plates

NOTES:

• The calcium carbonate will settle in agar plates before the agar has set, producing an opaque layer in the bottom.
• As the strain grows and acid is produced this will react with the calcium carbonate, causing it to dissolve and form zones of clearing immediately below the colonies.