Anaerobic ammonium oxidation coupled to Fe(III) reduction, known as Feammox, is a newly discovered nitrogen-cycling process, which serves an important role in the pathways of nitrogen loss in the environment. However, the specific types of microorganisms involved in Feammox currently remain unclear. In this study, we selected two groups of soil samples (paddy and mine), from considerably different habitats in South China, to acclimate Feammox colonies. The Paddy Group had a shorter lag period than the Mine Group, while the ammonium transformation rate was nearly equal in both groups in the mat...