Abstract:
The evolution of the biogeochemistry of iron through geological time is a useful example of the adaptation of single cell organisms to environmental change. Life has evolved such that iron is an essential nutrient for virtually every living cell. As the earth's atmosphere changed from an anaerobic reducing atmosphere to an aerobic oxidizing atmosphere containing a relatively high concentration of oxygen, the solubility, and therefore bioavailability, of iron decreased due to the oxidation of iron from the ferrous (Fe2+) to the ferric (Fe3+) form. This required the biosynthesis of iron chelators (siderophores) to make the iron bioavailable through chelation. Complexity theory is a useful paradigm to understand siderophore mediated iron transport in microbial communities.