Formation and Transformation of Iron‐Bearing Minerals by Iron(II)‐Oxidizing and Iron(III)‐Reducing Bacteria

Iron(II)-oxidizing bacteria (IOB) and iron(III)-reducing bacteria (IRB) encompass a wide diversity of species and metabolisms and have colonized various environments from the Precambrian. They display a set of adaptations to miscellaneous geochemical conditions, in particular from anoxic to oxic environments. One important consequence of IOB and IRB activities is the precipitation of Fe-bearing minerals. In the present chapter, we provide an overview of the Fe mineralogical diversity produced by these microorganisms in light of their specific metabolisms and physiological adaptations. As they may provide valuable biosignatures for the reconstruction of Earth–life coevolution, we inspect the specific properties of these Fe biominerals that may help discriminate them from abiotic counterparts. Some potential applications provided by these metabolisms are also reviewed.