Microorganisms influence corrosion by changing the electrochemical conditions at the metal/solution interface. These changes may have different effects, ranging from the induction of localized corrosion to corrosion inhibition. The key to the alteration of conditions at a metal surface and hence, the enhancement or inhibition of corrosion is the formation of a biofilm. On a biologically conditioned metal surtidcc microorganisms can induce corrosion inhibition in several ways: a) by neutralizing the action of a corrosive substance already present in the medium; b) by stabilizing a protective film on a metal surface or c) by inducing a decrease in the medium aggressiveness. Seldomly mentioned in the literature, microbial inhibition of corrosion could be a potentially useful tool to counteract many of the biodeterioration cases encountered in practice.
Keywords: microbial corrosion, microbiologicaliy influenced corrosion (MIC), biofilms, corrosion inhibition, extracellular polymeric substances (EPS), sulphate-reducing bacteria (SRB), Serratia marcescens