A perspective on corrosion inhibition by biofilms

A perspective is provided on corrosion inhibition by bacterial biofilms. Inhibition of general corrosion by biofilms has been reported for mild steel, copper, aluminum, and stainless steels. The mechanisms most frequently cited for the inhibition are formation of a diffusion barrier to corrosion products that stifles metal dissolution, consumption of oxygen by respiring aerobic microorganisms within the biofilm causing a diminution of that reactant at the metal surface, production of metabolic products that act as corrosion inhibitors (e.g., siderophores) or specific antibiotics that prevent proliferation of corrosion-causing organisms (e.g., sulfate-reducing bacteria), and formation of passive layers that are unique to the presence of microorganisms. The perspective will review biofilm formation and the processes that make it difficult to predict and control.