Accelerating corrosion of copper via Fe2+-assisted promotion of the electron transfer in the sulfate reduction process of sulfate-reducing bacteria (SRB)

Abstract

Sulfate-reducing bacteria (SRB) drive the anaerobic corrosion of copper through their unique sulfur metabolism electron transfer system. Within this system, cytochrome c (Cyt. c) acts as a key electron carrier, utilizing iron ions in its heme group to mediate sulfate reduction. Consequently, variations in environmental iron ion (Fe²⁺) concentration can directly impact SRB sulfate reduction activity and thus influence metal corrosion. This study employs electrochemical and transcriptomic analyses to elucidate the effect of environmental Fe²⁺ concentration on copper anaerobic corrosion, specifically examining the electron transfer chain in SRB (Desulfovibrio vulgaris) metabolism. Results demonstrate that elevated Fe²⁺ concentrations (191–765 μM) induce transcriptional activation of Cyt. c-related protein genes and significantly enhance expression of genes encoding the 4Fe-4S cluster domain. This upregulation promotes the production of hydrogen sulfide (H₂S), the metabolic end product of sulfate reduction, leading to accelerated copper corrosion (increasing from 0.26 ± 0.07 mg/cm² to 0.49 ± 0.15 mg/cm²). These findings provide a new perspective for understanding rapid copper corrosion in SRB and iron containing environments and offer a critical reference for evaluating the potential use of iron sacrificial anodes to protect copper and its alloys.