Comparative Analysis of Aerobic vs. Anaerobic Environments on Microbiologically Influenced Corrosion in Industrial Water

Microorganisms frequently influence the corrosion of metal materials. Recently, the dynamics of microbial communities during steel corrosion were revealed through molecular genetic analyses. During the progression of corrosion, microbial communities with high abundances of sulfate-reducing bacteria (SRB) are established, even under aerobic conditions. However, whether the establishment of an anaerobic environment is the major factor in SRB enrichment is unclear. To assess the relationship among corrosion behavior, accumulation of SRB, and anaerobic conditions, immersion tests were conducted under both aerobic and anaerobic conditions in the same industrial water. The corrosion rate of carbon steel was found to significantly decrease under anaerobic conditions compared to that under aerobic conditions. On the other hand, no significant corrosion was observed in stainless steel and copper alloys. Furthermore, changes in the microbial community structure under anaerobic conditions were found to notably differ from those observed under aerobic conditions. Finally, SRB accumulation was not observed under anaerobic conditions. Altogether, the heterogeneous corrosion product developed through microbial activity may support the efficient accumulation of SRB in the corrosion products. Herein, not only the establishment of a low dissolved oxygen environment, but also other microbial activities were found to be important for the accumulation of SRB in corrosion products, highlighting the importance of microorganisms other than SRB. Such a finding contributes to our understanding of the mechanism of microbiologically influenced corrosion.