What do nitrifying bacteria do!

1. remove nitrogen gas from ammonium

2. absorb nitrates through soil

3. convert ammonium to nitrates

4. release nitrogen from fossil fuels

The answer is: 3. convert ammonium to nitrates. This process is called nitrification, and is facilitated by nitrifying bacteria within an aerobic environment through the oxidation of ammonium (NH4) to first nitrite (NO2) and then to nitrate (NO3). This is very important for the nitrogen cycle in soils and also in water. Under anoxic conditions, denitrification occurs.