MinOx · Geomicrobiology of Fe(II)-bearing Minerals and Nitrate-Reducing Iron-Oxidizing microbial cultures

Nitrate-Reducing Iron-Oxidizing (NRFeOx) microorganisms, which couple Fe(II) oxidation to nitrate reduction using organic matter or carbon dioxide as a carbon source, play an essential role on a global scale in three of the most important biogeochemical cycles: iron, carbon and nitrogen. From an ecological point of view, NRFeOx microorganisms are key players in several processes such as the biological oxidation of Fe in anoxic and dark environments, the reduction of atmospheric carbon dioxide and the removal of nitrate from polluted groundwater aquifers.The aim of this project is to analyze the ability of NRFeOx communities to thrive using Fe(II)-bearing minerals as an energy source, the ecological consequences of the mineral transformation, and to explore the mechanism of microorganism-mineral interaction, which is crucial to fully understand their role in natural environments. First, culture techniques will be applied to identify Fe(II)- bearing minerals that can be oxidized by NRFeOx communities. Subsequently, Molecular Biology techniques will be applied to analyze the structure and distribution of NRFeOx communities when they grow using minerals as an energy source and to determine the main actors in the process. Finally, analytical microscopy techniques will be used to study, at the nanometer scale, the interaction between specific microorganisms with the mineral surface. For this purpose, state-of-the-art techniques such as Confocal Raman Microscopy, Scanning Electron Microscopy-Energy Dispersive X-Ray Spectroscopy and X-Ray Photoemission Electron Microscopy will be correlated with Fluorescence In Situ Hybridization and Fluorescence Microscopy.The data obtained in the MinOx project could not only be applied to biotechnological processes and integrated into predictive models for the management of nitrate-contaminated waters but will also unveil a totally unknown area of geomicrobiology: the transformation of Fe(II) minerals by NRFeOx microorganisms.