Stainless steel corrosion via direct iron-to-microbe electron transfer by Geobacter species

• Published in: The ISME Journal Vol. 15; no. 10; pp. 3084 - 3093
• Main Authors: Tang, Hai-Yan, Yang, Chuntian, Ueki, Toshiyuki, Pittman, Conor C., Xu, Dake, Woodard, Trevor L., Holmes, Dawn E., Gu, Tingyue, Wang, Fuhui, Lovley, Derek R.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-10-2021; Nature Publishing Group
• Subjects: 14/19; 14/28; 14/34; 14/63; 38/22; 38/39; 38/44; 38/70; 38/77; 42/44; 42/56; 45/22; 45/23; 45/29; 631/208/325/2482; 631/326/46; Bacterial corrosion; Biomedical and Life Sciences; Corrosion; Corrosion mechanisms; Cytochromes; Ecology; Electric contacts; Electron transfer; Electrons; Evolutionary Biology; Genetic modification; Geobacter - genetics; Hydrogenase; Iron; Life Sciences; Metal surfaces; Microbial corrosion; Microbial Ecology; Microbial Genetics and Genomics; Microbiology; Microorganisms; Stainless Steel; Stainless steels
• ISSN: 1751-7362; 1751-7370
• DOI: 10.1038/s41396-021-00990-2

Microbial corrosion of iron-based materials is a substantial economic problem. A mechanistic understanding is required to develop mitigation strategies, but previous mechanistic studies have been limited to investigations with relatively pure Fe(0), which is not a common structural material. We report here that the mechanism for microbial corrosion of stainless steel, the metal of choice for many actual applications, can be significantly different from that for Fe(0). Although H
2
is often an intermediary electron carrier between the metal and microbes during Fe(0) corrosion, we found that H
2
is not abiotically produced from stainless steel, making this corrosion mechanism unlikely.
Geobacter sulfurreducens
and
Geobacter metallireducens,
electrotrophs that are known to directly accept electrons from other microbes or electrodes, extracted electrons from stainless steel via direct iron-to-microbe electron transfer. Genetic modification to prevent H
2
consumption did not negatively impact on stainless steel corrosion. Corrosion was inhibited when genes for outer-surface cytochromes that are key electrical contacts were deleted. These results indicate that a common model of microbial Fe(0) corrosion by hydrogenase-positive microbes, in which H
2
serves as an intermediary electron carrier between the metal surface and the microbe, may not apply to the microbial corrosion of stainless steel. However, direct iron-to-microbe electron transfer is a feasible route for stainless steel corrosion.