Structure Change of Iron Plaque Induced by Iron-Reducing Bacteria Inhibits Ciprofloxacin Uptake by Plants

Antibiotic pollution in the environment poses stress to plants. Iron plaque on plant roots plays a vital role in inhibiting the uptake of pollutants by plants. However, the role of environmental factor-driven alterations in iron plaque on plant uptake of the pollutant remains unclear. In this study, we selected Shewanella oneidensis MR-1, renowned for its iron-reduction capabilities, to explore its influence on the formation of iron plaque and subsequent uptake and transformation of ciprofloxacin (CIP) by plants. The presence of S. oneidensis MR-1 induced significant modifications in iron plaque composition, leading to a reduction in the iron plaque amount and an increase in ferrihydrite content within iron plaque. The changes in iron plaque composition substantially enhanced CIP immobilization on the plant root surface, thereby impeding both the uptake and apical translocation of CIP, resulting in a marked reduction in CIP-induced phytotoxicity. Furthermore, iron plaque formed with the participation of S. oneidensis MR-1 accelerated the removal of CIP from solution and induced a greater generation of oxidative degradation products. This study underscores the potential of microorganisms to influence the formation of rhizosphere iron plaque and inhibit plant uptake of pollutants, providing novel insights into safe production practices and pollutant degradation strategies.