Denitrifier

noun

1. That which destroys or prevents the formation of nitric acid or nitrates, as certain ferments in the decomposition of nitrogenous organic matter.
2. In bacteriology, any micro-organism which is capable of breaking down nitrates into nitrites, and nitrites into ammonia compounds, or of liberating nitrogen from any of these.
3. An organism that engages in denitrification, the removal of nitrates from the environment