Biocorrosion of 5083 aluminium alloy by Citrobacter freundii SKC-4 in seawater

The 5083-aluminium alloy, a widely utilized aluminium-magnesium alloy known for its high strength and excellent corrosion resistance, is commonly employed in various applications, including shipbuilding. Despite its inherent resistance to seawater, the presence of microorganisms such as sulphate reducing bacteria (SRB) significantly exacerbates its corrosion. In this study, immersion and electrochemical tests were performed on 5083 aluminium alloy in both sterilized seawater and seawater enriched with SRB Citrobacter freundii SKC-4. Prior to the corrosion tests, Citrobacter freundii SKC-4 was cultivated in modified Luria-Bertani medium under specific conditions. The results demonstrated increased corrosion rates in the presence of the bacteria, with extended immersion leading to greater weight loss of the alloy. Analyses using Scanning Electron Microscope-Energy Dispersive Spectroscopy Mapping and Fourier Transform Infrared confirmed the formation of biofilms by Citrobacter freundii SKC-4 on the alloy's surface, clearly indicating the occurrence of biocorrosion.