Microbiologically influenced corrosion of metals is prevalent in both natural and industrial environments, causing enormous structural damage and economic loss. Exactly how microbes influence corrosion remains controversial. Here, we show that the pitting corrosion of stainless steel is accelerated in the presence of Shewanella oneidensis MR-1 biofilm by extracellular electron transfer between the bacterial cells and the steel electrode, mediated by a riboflavin electron shuttle. From pitting measurements, X-ray photoelectron spectroscopy and Mott-Schottky analyses, the addition of an increased amount of riboflavin is found to induce a more defective passive film on the stainless steel. Electrochemical impedance spectroscopy reveals that enhanced bioanodic and biocathodic process can both promote the corrosion of the stainless steel. Using in situ scanning electrochemical microscopy, we observe that extracellular electron transfer between the bacterium and the stainless steel is bidirectional in nature and switchable depending on the passive or active state of the steel surface.

受微生物影响的金属腐蚀在自然和工业环境中都很普遍，会造成巨大的结构损坏和经济损失。微生物究竟如何影响腐蚀仍然存在争议。在这里，我们表明在Shewanella oneidensis的存在下，不锈钢的点蚀会加速MR-1 生物膜通过细菌细胞和钢电极之间的细胞外电子转移，由核黄素电子穿梭介导。从点蚀测量、X 射线光电子能谱和 Mott-Schottky 分析中，发现添加增加量的核黄素会在不锈钢上产生更多缺陷的钝化膜。电化学阻抗谱表明，增强的生物阳极和生物阴极过程都可以促进不锈钢的腐蚀。使用原位扫描电化学显微镜，我们观察到细菌和不锈钢之间的细胞外电子转移本质上是双向的，并且可以根据钢表面的被动或主动状态进行切换。