Eutrophication of seawater intensified biocorrosion of copper caused by Desulfovibrio vulgaris biofilm

Seawater eutrophication increases the abundance of microbial communities and metabolic activities of microorganisms in seawater and potentially impacts microbiologically influenced corrosion (MIC). Copper as a common material in marine structures and nuclear waste containers faces serious MIC problems. This study investigated the copper MIC caused by Desulfovibrio vulgaris in anaerobic artificial seawater (ASW) with four eutrophication levels: pure ASW (PASW), oligotrophication ASW (OASW), mesotrophication ASW (MASW), and eutrophication ASW (EASW). It was found that the copper MIC increased along with the eutrophication level. The higher eutrophication led to an increase in the planktonic and Cu surface sessile D. vulgaris cell counts and H2S concentration in the headspace of anaerobic vials. The resultant weight loss and maximum pitting depth of copper in OASW were 2.0 and 2.4 times those in PASW, while their values in EASW were 2.8 and 4.2 times after 10 d of incubation, respectively. The experimental results combined with a bioenergetic analysis in this study indicated the copper MIC caused by D. vulgaris as belonging to biogenic H2S corrosion (i.e., metabolite MIC or M-MIC), which was further confirmed by the identical cytochrome c (Cyt c) (redox-active protein for extracellular electron transfer) expression levels of the planktonic D. vulgaris cells and sessile cells on copper.