Accelerated cathodic reaction in microbial corrosion of iron due to direct electron uptake by sulfate-reducing bacteria
By Venzlaff, Hendrik; Enning, Dennis; Srinivasan, Jayendran; Mayrhofer, Karl J.J.; Hassel, Achim Walter; Widdel, Friedrich & Stratmann, Martin
Published in Corrosion Science
2013
Abstract
Microbially influenced iron corrosion by sulfate-reducing bacteria (SRB) is conventionally attributed to the chemical corrosiveness of H2S, facilitated abiotic H+-reduction at deposited FeS, and biological consumption of chemically formed ('cathodic’) H2. However, recent studies with corrosive SRB indicated direct consumption of iron-derived electrons rather than of H2 as a crucial mechanism. Here, we conducted potentiodynamic measurements with iron electrodes colonized by corrosive SRB. They significantly stimulated the cathodic reaction, while non-corrosive yet H2-consuming control SRB had no effect. Inactivation of the colonizing bacteria significantly reduced current stimulation, thus confirming biological catalysis rather than an abiotic cathodic effect of FeS.