Effect of elevated ferrous ion to the gene expression of Desulfovibrio ferrophilus IS5

Here, we investigate how excess Fe2+ modulates EEU in Desulfovibrio ferrophilus IS5, a strain that causes severe anaerobic iron corrosion via outer-membrane cytochromes (OMCs)-mediated electron uptake. We show that IS5 grown with elevated Fe2+ exhibits substantially enhanced EEU.

This enhancement arises through two complementary mechanisms: (i) increased abundance of functional OMCs via upregulation of a cytochrome assembly protein, and (ii) an additional electron transfer route mediated by FeS nanoparticles precipitated on the IS5 outer membrane. Remarkably, IS5 with low OMCs expression but biosynthesized FeS can rapidly shift to EEU before OMCs induction. These findings suggest that during iron corrosion, when IS5 cells are embedded within thick corrosion crusts and biofilms and face both high Fe2+ concentrations and organic limitation, they exploit OMCs and FeS nanoparticles in parallel to sustain high-rate EEU from iron.