Corrosion of iron-containing metals under sulfate-reducing conditions is an economically important problem. Microbial strains now known as  served as the model microbes in many of the foundational studies that developed existing models for the corrosion of iron-containing metals under sulfate-reducing conditions. Proposed mechanisms for corrosion by include: (1) H consumption to accelerate the oxidation of Fe coupled to the reduction of protons to H; (2) production of sulfide that combines with ferrous iron to form iron sulfide coatings that promote H production; (3) moribund cells release hydrogenases that catalyze Fe oxidation with the production of H; (4) direct electron transfer from Fe to cells; and (5) flavins serving as an electron shuttle for electron transfer between Fe and cells. The demonstrated possibility of conducting transcriptomic and proteomic analysis of cells growing on metal surfaces suggests that similar studies on corrosion biofilms can aid in identifying proteins that play an important role in corrosion. Tools for making targeted gene deletions in are available for functional genetic studies. These approaches, coupled with instrumentation for the detection of low concentrations of H, and proven techniques for evaluating putative electron shuttle function, are expected to make it possible to determine which of the proposed mechanisms for corrosion are most important.