Conductive magnetite nanoparticles considerably accelerated carbon steel corrosion by electroactive Desulfovibrio vulgaris biofilm

Carbon steel microbiologically influenced corrosion (MIC) by sulfate reducing Desulfovibrio vulgaris belongs to extracellular electron transfer MIC (EET-MIC). Adding 20 ppm (w/w) Fe3O4 magnetite nanoparticles (MNPs) to ATCC 1249 culture medium did not alter sessile and planktonic cell counts significantly, but it caused 59% more weight loss and 85% deeper pit depth, respectively after 7 days of incubation. Electrochemical data corroborated the increases. In comparison, D. vulgaris MIC of Cu was not affected by 20 ppm MNPs because it belongs to metabolite MIC (M-MIC) without EET. Thus, MNPs can be a useful tool to distinguish some EET-MIC cases from M-MIC.