Interspecies electron transfer of mixed-species biofilms in microbial corrosion of metals: mechanisms and mitigation strategies

Biofilm formation on the surfaces of metallic materials can initiate microbiologically influenced corrosion (MIC), a significant issue for numerous industries, including oil and gas, nuclear power, and marine platforms. Despite notable advancements in understanding biocorrosion mechanisms of electroactive microbes using pure microbial cultures, these culture studies do not reveal the complexity of corrosion in real environments because microorganisms do not naturally live in isolation but tend to develop very complex interactions among species. Yet, the mechanisms of multispecies biofilms in MIC are poorly understood. This review comprehensively discusses mechanisms through which multispecies biofilms contribute to the corrosion of various metallic materials via mediated interspecies electron transfer (MIET) and direct interspecies electron transfer (DIET). IET-MIC facilitated by nanomaterials or deposits is also discussed in detail. The review further elaborates on the current mitigation strategies, such as extracellular enzymes, cell-signaling inhibitors, secretion of antibiotics, and antimicrobial coatings for practical mitigation of MIC. This review aims to raise awareness among MIC researchers about the complexity of corrosion induced by multispecies biofilms, and challenges associated with mitigation strategies.