Steel rust layers immersed in the South China Sea with a highly corrosive Desulfovibrio strain

Abstract

Although it is well known that microbes play a significant role in marine corrosion, few studies have systematically studied the relationship between microorganisms and corrosion products under long-term immersion. In this study, the corrosion characteristics of the rust layer formed on carbon steel immersed in the South China Sea for 5.5 years were investigated using various surface analysis and microbial community analysis techniques. Magnetite (Fe3O4), iron sulfide, and green rust were identified in the inner rust layer. The middle rust layer was composed of maghemite (γ-Fe2O3), and some Fe3O4 and mackinamite were also detected. The outer rust layer contained several Fe(III)-oxyhydroxides, and it had a large number of fouling organisms attached to it. In all of the rust layers, anaerobic sulfate-reducing bacteria (SRB) were the dominant bacteria, and they may have played a key role in the formation of the corrosion products. One SRB strain (Desulfovibrio bizertensis SY-1) with a highly corrosivity (13.561 mg/cm2) was isolated from these rust layers, and its physiological and metabolic characteristics were studied. These results expand the membership of corrosive SRB and establish a better understanding of marine microbiologically influenced corrosion (MIC).

Microbially Influenced Corrosion of Steel in Marine Environments: A Review from Mechanisms to Prevention

“…Recent advances in genomics and metabolic pathways have led to new insights into the ecophysiology and distribution of SRB in the marine environment. For instance, studies have demonstrated that SRB is the primary microorganism involved in the long-term seawater immersion process [ 17 ]. Prominent SRB species such as Desulfovibrio and Desulfobacter have been detected in the inner layer of carbon steel, with a significantly higher abundance index than other bacterial species [ 18 ].…”

Role of Fe oxide in the underdeposit corrosion of pipeline steel in oilfield produced water containing SRB

“…[7][8][9] Furthermore, oxidants such as sulfate, nitrate, and carbon nutrients readily available in oilfield produced water boost microbial metabolism and cell proliferation. [9,10] According to Dong et al [11] microorganisms synergize with the rust layers formed on carbon steel in the marine environment to exacerbate MIC. Studying the contribution of each component in the deposit will be helpful in a better understanding of the UD-MIC mechanism.…”