English: Nitrification and denitrification

- Nitrification:

1. 10 ml sterile 10% MgCO 3 (or CaCO 3) solutions is to be mixed with 100 ml of the medium Winogradsky with (NH 4) 2 SO 4 in an Erlenmeyer flask.

2. 1 g of soil is to be transferred into the Erlenmeyer flask.

3. The contents are to be incubated at room temperature for 7 days.

4. After which, and every two days there forth, 1 ml aliquots are to be transferred in test tubes.

5. 2 drops of sulfanilic acid (Griss I) and 2 drops of α-naphtylamine (Griss II) are to be added in the test tubes.

RESULTS: The presence of nitrates will demonstrate a rosy-red color of the test tube solution. Full oxidation of the present ammonium in Winogradsky I into nitrates requires a time frame of about 2-3 weeks.

- Denitrification:

1. 10 ml sterile 10% MgCO 3 (or CaCO 3 ) solutions is to be mixed with 100 ml of the medium Winogradsky with NaNO 2 in an Erlenmeyer flask.

2. 1 g of soil is to be transferred into the Erlenmeyer flask.

3. The contents are to be incubated at room temperature for 4 days.

4. After which, and every two days there forth, 1 ml aliquots are to be transferred in test tubes.

5. 2 drops of sulfanilic acid (Griss I) and 2 drops of α-naphtylamine (Griss II) are tobe added in the test tubes. Development of a rosy-red color is indicative of the presence ofnitrates and nitrites.

6. Eventually, once a test tube with no color change is observed (no remaining nitrates), a 1 ml aliquot of the Erlenmeyer flask is to be transferred into a test tube wand 2 drops of diphenylamine and 2 drops of concentrated sulphuric acid.

RESULT: Development of a blue color shows the presence of nitrates as the diphenylamine is oxidized.

Planned and performed by Sofija Kostandinovska, Institute of Biology, FNSM, Ss. Cyril and Methodius University, Skopje, Macedonia.