Role of Microbial Communities in Linking Fe (hydr)Oxide Transformation and Nutrient Cycling.

Iron (hydr)oxides are commonly found in soils and sediments in a wide variety of

forms ranging from poorly- to highly-ordered oxides. The structure, composition

and degree of crystallinity of these minerals vary greatly depending on the physical

and chemical conditions of their surroundings. The transformation of Fe (hydr)

oxides under microbial Fe(III)-reducing and chemical Fe(II)-oxidizing conditions is

well characterized. However, Fe(II) oxidation in anaerobic environments by bacteria

that couple Fe(II) oxidation to nitrate reduction remains poorly understood.

Linking geochemical processes to changes in microbial community composition

and activity is crucial for revealing the fate of nitrogen and carbon in soils and

sediments, and elucidating key biogeochemical features that govern nitrate-dependent

Fe(II) oxidation.