Buried and submerged metal infrastructure such as pipelines, bridge foundations, and underground storage tanks is continually exposed to corrosive microbial communities that drive microbiologically influenced corrosion (MIC). These bacteria form biofilms that accelerate localized metal attack, producing pits and perforations that can lead to severe structural failures. A notable example is the 2015 Aliso Canyon methane leak in California, where MIC contributed to the rupture of a storage well, releasing massive amounts of methane and forcing thousands of residents to evacuate. This project investigates coating-based strategies to mitigate MIC by evaluating the performance of inorganic and organic coatings on metal substrates. In this study, coated and uncoated metal samples are exposed to different strains of corrosive bacteria to examine how each strain interacts with the coating chemistry. After exposure, biofilm formation is monitored to assess how coating properties influence microbial attachment and growth. Some coatings exhibit antibacterial or toxic effects, suppressing bacterial proliferation, while others allow biofilms to form but alter their structure, adhesion strength, or stability. Adhesion testing is used to determine how firmly biofilms attach to each coating, providing insight into whether biofilm presence enhances or reduces the likelihood of corrosion progression. Biofilm layers are also compared to naturally formed passivation films to evaluate whether microbial layers may, in some cases, offer protective features. To extend these findings to real-world conditions, coated samples will be embedded in soil for field exposure, where natural bacterial communities can colonize the surfaces. This approach enables comparison between controlled laboratory interactions and complex environmental MIC behavior. Overall, this work aims to identify coatings that either resist harmful bacterial activity or support benign biofilms that reduce corrosion risk. The outcomes will inform corrosion mitigation strategies for critical infrastructure systems vulnerable to MIC, helping prevent leaks, environmental contamination, and potential large-scale failures.
