IRON IN MICROBIAL METABOLISMS

Microbes are intimately involved On the Iron cycle. First, acquisition of iron by microorganisms for biochemical requirements is a key process in the iron cycle in oxygenated, circumneutral pill environments, where the solubility of Fe(III) (oxyhydr)oxides is extremely low. Second, a number of aerobic (using O-2) and anaerobic (living in the absence of O-2) autotrophic bacteria gain energy for growth from the oxidation of dissolved and solid-phase Fe(II) compounds to Fe(III) (oxyhydr)oxides. Third, heterotrophic Fe(III)-reducing bacteria close the chemical loop by reducing solid-phase Fe(III) minerals back to dissolved and solid-phase Fe(II). Together these metabolic processes control the partitioning of the Earth's fourth most abundant crustal element, and they are additionally tied to the cycling of several major nutrients (e.g. carbon, oxygen, nitrogen, sulfur) and trace elements (e.g. phosphorus, nickel) in modern and ancient environments.