Electron transfer mediator PCN secreted by aerobic marine Pseudomonas aeruginosa accelerates microbiologically influenced corrosion of TC4 titanium alloy

Titanium alloys possess excellent corrosion resistance in marine environments, thus the possibility of their corrosion caused by marine microorganisms is neglected. In this work, microbiologically influenced corrosion (MIC) of TC4 titanium alloy caused by marine Pseudomonas aeruginosa was investigated through electrochemical and surface characterizations during a 14-day immersion test. Results revealed that the unstable surface caused by P. aeruginosa resulted in exposure of Ti2O3 and severe pitting corrosion with maximum pit depth of 5.7 mu m after 14 days of incubation. Phenazine-1-carboxylate (PCN), secreted by P. aeruginosa, promoted extracellular electron transfer (EET) and accelerated corrosion. Deletion of the phzH gene, which codes for the enzyme that catalyzes PCN production, from the P. aeruginosa genome, resulted in significantly decreased rates of corrosion. These results demonstrate that TC4 titanium alloy is not immune to marine MIC, and EET contributes to the corrosion of TC4 titanium alloy caused by P. aeruginosa. (C) 2021 Published by Elsevier Ltd on behalf of The editorial office of Journal of Materials Science & Technology.