Dual role of marine bacteria Pseudoalteromonas NCIMB 2021 in corrosion of mild steel in artificial seawater

The modifications in corrosion resistance and local surface modifications caused by the colonization of Pseudoalteromonas NCIMB 2021 bacteria on mild steel in artificial seawater were investigated using electrochemical techniques, Scanning Electron Microscopy and Time-of-Flight Secondary Ion Mass Spectrometry. A dual role of these bacteria on corrosion resistance was observed and characterized. While an improvement in corrosion resistance was obtained in the presence of the bacteria, the colonized surface is locally modified and once the bacteria are removed, the previously colonized areas are exposed, leading to enhanced localized corrosion. • Pseudoalteromonas NCIMB 2021 significantly reduces mild steel corrosion rates as long as it remains on the surface. • Bacterial colonization leads to local surface modifications. • Removal of bacteria exposes mild steel to enhanced localized corrosion. • 3D chemical maps obtained with ToF-SIMS reveals local deterioration and pit formation.