Nitrogen-fixing bacteria is(are) indicated by the letter(s) . The nitrogen cycle. Each letter indicates a definite member of this cycle. Letter A indicates bacteria that convert nitrates (NO3 minus) to nitrogen (N2) and release it to the atmosphere. Letter B marks bacteria that transform nitrites (NO2 minus) into nitrates (NO3 minus). Letter C marks bacteria that transform ammonium (NH4 plus) into nitrites (NO2 minus). Letter D marks bacteria that transform nitrogen (N2) of the atmosphere to ammonium (NH4 plus). Letter E marks bacteria that assimilate nitrogen (N2) of the air and are located in the root nodules. Nitrogen-fixing bacteria is(are) indicated by the letter(s) . The nitrogen cycle. Each letter indicates a definite member of this cycle. Letter A indicates bacteria that convert nitrates (NO3 minus) to nitrogen (N2) and release it to the atmosphere. Letter B marks bacteria that transform nitrites (NO2 minus) into nitrates (NO3 minus). Letter C marks bacteria that transform ammonium (NH4 plus) into nitrites (NO2 minus). Letter D marks bacteria that transform nitrogen (N2) of the atmosphere to ammonium (NH4 plus). Letter E marks bacteria that assimilate nitrogen (N2) of the air and are located in the root nodules. D and E B and C A A and B C and D