When released, most of the ammonium is often chemically altered by a specific type of autotrophic bacteria (bacteria that belong to the genus Nitrosomonas) into nitrite (NO2 -).    From Wordnik.com.  [Nitrogen cycle] Reference

CBIO's N-Series (Nitrosomonas and Nitrobacter) are high purity high activity strains of ammonia and nitrite removing bacteria.    From Wordnik.com.  [edie.net - Latest News] Reference

When released, most of the ammonium is often chemically altered by a specific type of autotrophic bacteria (bacteria that belong to the genus Nitrosomonas) into nitrite (NO 2 -).    From Wordnik.com.  [Featured Articles - Encyclopedia of Earth] Reference

Nitrosomonas europaea.    From Wordnik.com.  [PLoS ONE Alerts: New Articles] Reference