Isolation and characterization of an ammonium-oxidizing iron reducer: Acidimicrobiaceae sp. A6

Acidimicrobiaceae sp. A6 (ATCC, PTA-122488), a strain that has been previously reported to play a key role in the oxidation of ammonium (NH(4)(+)) under iron reducing conditions, has now been isolated from riparian wetland soils in New Jersey, USA. Incubations of this strain in a medium containing ferrihydrite as the ferric iron [Fe(III)] source, CO(2) as the carbon source, under room temperature, and a pH of 4.5, resulted in 52% of NH(4)(+) removal over a 20-day incubation period, while reducing Fe(III) in the expected stoichiometric ratio when NH(4)(+) was oxidized to nitrite with Fe(III) as the electron acceptor. This study demonstrates that this new isolated strain is capable of oxidizing NH(4)(+) while reducing iron under anaerobic conditions.