Both Nitrosomonas spp. and Nitrobacter spp. can be cultured after using Stephenson's medium. The composition of medium for Nitrosomonas are as follows: Ammonium sulphate 20.0g, Dipotassium phosphate 7.5g, Potassium dihydrogen phosphate 2.5g, Magnesium sulphate 0.3g, Ferrus sulphate 0.1g, Manganese sulphate 0.1g, Calcium chloride 0.02g, Distilled water 1000mL; Dilute the above medium, 1 part in 100 parts of water, for liquid media and add silica gel.
For Nitrobacter spp., the composition of the media are the same as above, except for the substitution of Sodium nitrate of the same amount instead of Ammonium sulphate.
1. 0.5 (NH4) 2SO4; 1.0 K2HPO4; 0.03 FeSO4∙7 H20; 0.3 NaCl; 0.3 MgSO4∙7 H2O; 7.5 CaCO3. The second medium (0.006 NaNO2; 1.0 K2HPO4; 0.3 NaCl; 0.1 MgSO4∙7 H2O; 0.03 FeSO4∙7 H2O; 0.3 CaCl2 and 1.0 CaCO3). It is used for the cultivation of all nitrifiers (ammonium and nitrite oxidizers) .
2. 0.006 NaNO2; 1.0 K2HPO4; 0.3 NaCl; 0.1 MgSO4∙7 H2O; 0.03 FeSO4∙7 H2O; 0.3 CaCl2 and 1.0 CaCO3). It can be used for the cultivation and enumeration of nitrite oxidizers only.
There are some modifications that you can find in the articles mentioned above.
Winogradsky medium or modified Winogradsky’s medium are alternative solution:
3. Winogradsky medium:
Nitrosomonas could be isolated using Winogradsky medium for nitrification phase 1 (.NH4)2SO4, 2.0 g;K2HPO4, 1.0 g;MgSO4.7H2O, O.5 g; NaCl,2.0 g; FeSO4.7H2O, 0.4 g; CaCO3 0.01, agar 15.0 g; distilled water 1000 ml).
Nitrobacter could be isolated using Winogradsky medium phase 2 (KNO2 0.1 g; Na2-Co3,1.0 g; NaCl, 0.5 g; FeSO4.7H2O, 0.4 g agar 15.0 g; distilled water 1000 ml).