Stability and reactivity of solid metal or mineral surfaces in contact with bacteria are critical properties for development of biocorrosion protection and for understanding bacteria−solid environmental interactions. Here, we opted to work with nanosheets of iron nanolayers offering arbitrarily large and stable areas of contact that can be simply monitored by optical means. We focused our study on the sediments' bacteria, the strain Shewanella oneidensis WT MR-1, that served as models for previous research on electroactivity and iron-reduction effects. Data show that a sudden uniform corrosion appeared after an early electroactive period without specific affinities and that iron dissolution induced rapid bacterial motions. By extending the approach to mutant strains and three bacterial species, we established a correlation between corrosion onset and oxygen-depletion combined with iron reduction and demonstrated bacteria's extraordinary ability to transform their solid environments.