Microbial Fe Oxidation and Biomineralization: Visualizing At the Nanomineral, Pore, and Biofilm Scales.

Microbial Fe oxidation is a poorly understood, but likely widespread process in soils and other Fe-rich sediments. This is likely especially important where redox fluctuates between oxic and anoxic conditions. Fe-oxidizing microorganisms use Fe(II) as electron acceptor and either oxygen or nitrate as an electron donor, occupying soil/aquifer pores or forming biofilms and mats in aquatic environments. At neutral pH, these organisms precipitate copious biominerals, often associated with microbial organics. I will introduce several Fe-oxidizers we have cultured from soil and aquifers, and discuss their biomineralization processes and products in the context of pore-scale architecture and hydrology. In addition, I will show how our studies of modern day Fe-oxidizers helps us to develop biosignatures and therefore insights into geological Fe deposits.