Iron Cycling: Mechanisms of Iron Oxidation and Reduction

This lecture discusses the mechanisms of iron oxidation and reduction in various microbial environments. It begins with the challenges faced by acidophilic aerobic Fe(II) oxidizers, particularly the low redox potential of iron and the acidic conditions they thrive in. The instructor explains how these organisms utilize iron(II) as an electron donor and oxygen as an electron acceptor, leading to the production of iron(III) and water. The lecture highlights the adaptations that allow these microbes to survive in such extreme conditions, including specialized proteins that facilitate electron transfer. The discussion then shifts to aerobic neutrophilic Fe(II) oxidizers, who face different challenges due to the rapid chemical oxidation of iron at neutral pH. The lecture concludes with the environmental implications of microbial iron cycling, emphasizing its role in organic carbon oxidation and bioremediation of contaminated sites. The instructor provides examples of various iron-oxidizing and iron-reducing organisms, illustrating their ecological significance.