Detecting the structural evolution of passive film induced by Shewanella oneidensis MR-1 using aberration-corrected TEM

The formation of biofilm is generally known as a dominant factor for microbiologically influenced corrosion (MIC), and the mechanism of metal corrosion caused by microorganisms through extracellular electron transfer (EET) is widely recognized. Some investigations have discussed the interaction between bacteria and passive film, and oftentimes, not directly corroborated by experimental evidence. Here, we show the structural and compositional evolution of the passive films when interacting with Shewanella oneidensis MR-1. By means of aberration-corrected transmission electron microscope (Cs-corrected TEM) and electron energy loss spectrometer (EELS) analysis, we directly capture the loosening and locally thinning of the passive film induced by Shewanella oneidensis MR-1 and clarify that the passive film has undergone the electrochemical reducing process. This work provides new insights into the EET mechanism between microorganisms and metals.