Biofilm-driven Microbial Corrosion: Structure, Function, and Visualization

Abstract

Biofilms are structured microbial communities embedded in a self-produced matrix of extracellular polymeric substances (EPS) that adhere to material surfaces. On metal surfaces, biofilms can both accelerate and inhibit corrosion, suggesting that understanding their structural and functional properties is critical for effective corrosion control. This review introduces the fundamental characteristics of microbial biofilms, including their EPS composition, life cycle, and adaptive functions in response to environmental cues. Multispecies biofilms are the predominant state of natural environments, exhibiting metabolic cooperation, electron exchange, and structural robustness that is not often observed in laboratory monoculture conditions. The temporal and spatial dynamics of microbial association within complex biofilms are also highlighted.

We further discuss recent advances in biofilm imaging techniques, such as contentious-optimizing confocal reflection microscopy (COCRM), label-free autofluorescence analysis, and microfluidic devices. These tools have enabled non-invasive, real-time observation of living biofilms, revealing their structural plasticity and interactions with metal surfaces. Through these methods, biofilms are now increasingly viewed as dynamic ecosystems rather than static surface deposits.

Finally, we describe various mechanisms of microbiologically influenced corrosion (MIC), including acid production, extracellular electron transfer, and localized differential concentration. The EPS matrix could play a central role in creating microenvironments that induce corrosion. Understanding biofilms as living communities opens new possibilities for microbiologically influenced corrosion control. Integrating insights from microbiology, materials science, and electrochemistry is essential for the development of sustainable anti-corrosion technologies.