Microbes-mediated coupling of Fe(Ⅲ) reduction and ammonium oxidation

Abstract:

The redox processes of iron significantly influence secondary mineral formation, nutrient transformation, and the fate of contaminants. As a novel process of global iron cycle first discovered in anaerobic environment, microbes-mediated coupling of ammonium oxidation and Fe(Ⅲ) reduction (Feammox) accounts for up to 10% of ammonium oxidation in natural and agricultural ecosystems. Thus, it is of great significance for environmental protection and agricultural production. This review summarized the research on microbial Feammox in recent years, including its research history, related microbes, underlying mechanisms, influencing factors, and environmental significances. In Feammox, Acidimicrobiaceae sp. A6 and dissimilatory Fe-reducing bacteria (DIRB) are potential functional organisms, and pH, Fe(Ⅲ) concentration and speciation, carbon sources, and Mn(Ⅳ) oxides are the main environmental factors. Feammox might be driven by biological process alone, or by the biological-chemical coupling processes. As for the environmental significances, Feammox can reduce the greenhouse gas emission and influence heavy metal transformation, but it causes alternative N loss. Further investigations could focus on the cultivation of related microorganisms and the development of new research methods to further disclose the Feammox mechanism.