Eco-Friendly Bacterial Strains as Corrosion Inhibitors for Mild Steel in the Red Sea Water

In this study, bacterial strains were isolated from the Red Sea and identified as Pseudoalteromonas phenolica (BAC1), Pseudoalteromonas shioyasakiensis (BAC2), and Alteromonas mediterranea (BAC3). These isolates were investigated as eco-friendly corrosion inhibitors for mild steel in marine environments. Mild steel samples were immersed in natural seawater inoculated with cultured bacterial isolates at defined concentrations (OD₆₀₀ = 0.5), simulating biotic corrosion conditions over immersion periods of up to 24 weeks. Corrosion behavior was assessed using weight loss (WL) analysis, potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS). Molecular identification of the isolates was performed through 16S rRNA gene amplification and sequencing. The results revealed that all three bacterial strains significantly enhanced corrosion resistance, with the highest inhibition efficiencies observed in week 9 for BAC1 and week 1 for both BAC2 and BAC3. Electrochemical data indicated notable reductions in corrosion current densities and increases in charge transfer resistance, particularly for BAC2, which maintained superior inhibition (96.21%) even after 24 hours of exposure. Surface imaging confirmed the presence of biofilm layers that contributed to corrosion mitigation. These findings demonstrate the potential of Red Sea-derived bacteria as sustainable alternatives to conventional corrosion inhibitors in marine applications. integron, bla_GES-5-gcuE15-aph(3’)-XV-ISPa21e, was reported for the first time in this study.