Microbiologically influenced corrosion of Cu by nitrate reducing marine bacterium Pseudomonas aeruginosa

The microbiologically influenced corrosion (MIC) mechanisms of copper by Pseudomonas aeruginosa as a typical strain of nitrate reducing bacteria (NRB) was investigated in this lab study. Cu was immersed in deoxygenated LB-NO3 seawater inoculated with P. aeruginosa and incubated for 2 weeks. Results showed that this NRB caused pitting and uniform corrosion. The maximum pit depths after 7 d and 14 d in 125 mL anaerobic vials with 50 mL broth were 5.1 μm and 9.1 μm, accompanied by specific weight losses of 1.3 mg/cm2 (7 d) and 1.7 mg/cm2 (14 d), respectively. Electrochemical measurements corroborated weight loss and pit depth data trends. Experimental results indicated that extracellular electron transfer for nitrate reduction was the main MIC mechanism and ammonia secreted by P. aeruginosa could also play a role in the overall Cu corrosion process.