Microbial Oxidation and Reduction of Manganese and Iron

Abstract

The environmental distribution of iron and manganese, which are required trace metals for virtually all life, is strongly influenced by redox chemistry. The oxidized forms (Mn4+, Fe3+) are usually found as insoluble oxides, while the reduced forms (Mn2+, Fe2+) can be soluble. Biotic mediation of iron and manganese chemistry, which often involves changes in the redox states of these metals. Such activities, which can be indirect (pH/Eh alteration of the environment) or direct (via enzymes or binding components), are common to many bacterial groups. Biotic mediation may thus be important in metal deposition, mobilization and cycling, especially in stratified environments with well-developed oxic-anoxic interfaces. Conversely, the presence of large amounts of iron and manganese, often common in sediments, may be very important to both chemistry and biology of the environment.