Conversion of $NH_{3} \rightarrow NO_{2}^{-} \rightarrow NO_{3}^{-}$ is called:

Which of the following is true for nitrogen fixation?

Nitrifying bacteria:

The process of conversion of $2 NO_{3}^{-} \rightarrow 2 NO_{2}^{-} \rightarrow 2 NO \rightarrow N_{2}O \rightarrow N_{2}$ is called and is carried out by:

Nitrifying bacteria

The conversion of nitrate to nitrogen is called