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 as well as in the transport of fluids such as water and crude oil. The damages caused by MIC in these aforementioned applications have magnitude effect on the health and serenity of the ecosystem. Microorganisms often isolated from sites experiencing MIC are sulphate reducing bacteria (SRB). Other bacteria such as acid producing bacteria (APB), sulphate oxidizing bacteria (SOB), iron oxidizing bacteria (IOB) among many others also play active roles in causing MIC of metals, which mostly occur in a fluid or humid environment. The production of biofilm by these groups of bacterial has been demonstrated to be highly essential in causing MIC, which has impaired the natural habitat of most animals with detrimental effect on man. 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 effect on the environment at large. However, the use of non-corrosion causing bacteria can help in passivation of metal surface through formation of biofilm; production of antagonistic metabolites and their aerobic respiration. The biocompetitive exclusion is important in eliminating SRB from microbial community present in biofilms. Researchers need to focus more on microbial products with potentials to cause disintegration of biofilm in MIC.