Electroactive microorganisms-driven single-atom iron catalysis combats antibiotic-resistant bacteria: Unexpected ferroptosis mechanism

The rapid spread of antibiotic-resistant bacteria (ARB) is a global health threat. Electrochemically active bacteria (EAB) driven by iron (oxyhydr)oxides can combat ARB by generating reactive oxygen species (ROS). However, the roles of extracellular ROS and intracellular ROS from ferroptosis in ARB inactivation remain unclear. This study developed a system combining Shewanella oneidensis MR-1 with single-atom iron catalysts (Fe-SAC/g-C 3 N 4 - S. oneidensis MR-1) to inactivate antibiotic-resistant Escherichia coli (AR E. coli ). This system exhibited superior electron transfer capacity, facilitating dissimilatory iron reduction and Fenton reactions. Compared to Fe-SAC/g-C 3 N 4 , the AR E. coli inactivation rate constants decreased by 55.50 %, 51.47 %, and 48.99 % for goethite, hematite, and ferrihydrite, respectively. Molecular docking revealed that hydrophobic interactions mediated extensive binding sites and reduced binding free energy between Fe-SAC/g-C₃N₄ and proteins, enhancing ROS generation. Extracellular ·OH was a major contributor to inactivation, while Fe 2+ entry triggered ferroptosis, accounting for 20 % of AR E. coli inactivation. Transcriptomic analysis revealed significant upregulation of genes associated with oxidative stress responses and iron transport, alongside attenuation of energy metabolism and cellular respiration. These findings highlighted the dual roles of endogenous ROS from ferroptosis and exogenous ROS from Fenton-like reactions in ARB resistance reduction.