The Roles of Biofilms in Corrosion

Abstract

Microbial corrosion – also known as biological corrosion or microbiologically influenced corrosion (MIC) – is a type of corrosion that takes place on ceramics, concretes, stones or metals resulting from the presence and actions of microorganisms. The focus of this study, however, is on metals, owing to their universal applications in industrial and civil structures, biomedical devices, processing plants, aviation fuel system, nuclear waste storage facilities, oil rigs and in the transport of fluids such as water and crude oil. The damages caused by MIC in these aforementioned applications have magnitude effects on the health and serenity of the ecosystem. Microorganisms often isolated from sites experiencing MIC are sulfate-reducing bacteria (SRB). Other bacteria such as acid-producing bacteria (APB), sulfate-oxidizing bacteria (SOB) and iron-oxidizing bacteria (IOB), among many others, also play active roles in causing MIC of metals, which mostly occurs in the presence of fluid or humid environments. The production of biofilm by these groups of bacteria has been demonstrated to be highly essential in causing MIC, which has impaired the natural habitat of most animals with detrimental effects on humans. As such, prevention or mitigation of MIC is important. While there are numerous mitigation strategies in use, most of them are either expensive or have negative effects on the environment. However, the use of non-corrosion–causing bacteria can help in passivation of metal surfaces through formation of biofilm and production of antagonistic metabolites. Because of several advantages of this strategy, researchers need to focus more on microbial products with potential to cause disintegration of biofilm in MIC.