Extracellular electron transfer in microbial biocorrosion

Abstract

Biocorrosion by microbial biofilms is also termed microbiologically influenced corrosion (MIC). For many decades in MIC research, people focused on corrosive metabolites. In the past decade, researchers started to apply bioenergetics to MIC science research. They realized that extracellular oxidation of a metal can supply electrons for microbial respiration, which causes MIC. Because these electrons must be transported to the cytoplasm via extracellular electron transfer (EET), this kind of MIC is called EET-MIC, which is different from metabolite-MIC (M-MIC). Advances have been made to decipher inward EET involved in MIC. Carbon source starvation and electron mediator acceleration have been used to study impact of EET on MIC. More recently, manipulations of electron mediator-related genes have been used to elucidate EET in MIC. EET in energy metabolism in microbiology and EET for MIC are intertwined. Well-established corrosion research tools, especially electrochemical methods that are highly sensitive, are useful for microbiologists to study EET. • Extracellular electron transfer (EET) is involved in one key type of biocorrosion. • Direct electron transfer and mediated electron transfer are found in biocorrosion. • Experimental evidence for different types of EET in biocorrosion is discussed. • Newest proofs of EET in biocorrosion come from manipulations of EET-related genes. • Perspectives on EET importance in biocorrosion and future research are provided.