Final Report Summary - MICROFOX (Microbial formation of minerals by communities of Fe(II)-oxidizing bacteria in modern and ancient environments)
The formation of iron minerals by Fe(II)-oxidizing bacteria is linked to the global carbon and nitrogen cycle and controls the fate of nutrients, metals, and greenhouse gases. Within the MICROFOX project we demonstrated for the first time that the three microbial groups that contribute to Fe(III) mineral formation at neutral pH, i.e. microaerophilic, phototrophic and nitrate-reducing Fe(II)-oxidizers, are indeed present in the same habitat. Specifically we showed that they are present in freshwater sediments of Lake Constanze, Germany, and in marine sediments in Aarhus Bay, Denmark. We determined their abundance, activity and spatial distribution in these two habitats and quantified their metabolic rates, identified the biominerals produced, determined the fate of nickel and other metals and nutrients and quantified the emission of the important greenhouse gas N2O as a consequence of the activity of nitrate-reducing Fe(II)-oxidizers. Overall this has allowed us to evaluate the ecological importance of microbial Fe(III) mineral formation in both early Earth and modern environments, and advance the search for life on the Fe-rich planet Mars.