Proteomic and Oxidative Stress Insights into Cr(VI) and Chlorpyrifos Co- removal by FeO/C-Shewanella oneidensis MR-1

Abstract This study constructed a composite system using Shewanella oneidensis MR-1 and iron oxide-loaded biochar (FeO/C) to investigate the simultaneous removal of Cr(VI) and chlorpyrifos (CPF). The system achieved removal efficiencies of 73.47% for Cr(VI) and 70.12% for CPF within 144 h, fitting a pseudo-first-order kinetic model (k Cr > k CPF ). SEM confirmed FeO/C as an effective colonization substrate facilitating bacterial adaptation. Oxidative stress analysis revealed an initial surge in reactive oxygen species that activated antioxidant enzymes (e.g., SOD, CAT), culminating in glutathione depletion and elevated malondialdehyde by 144 h. Proteomic profiling indicated that the upregulation of thioredoxin (trxC) and iron storage proteins (bfr) was crucial for maintaining redox balance and electron transfer. Furthermore, enriched metabolic pathways supported the energy demands for detoxification, elucidating the adaptive molecular mechanisms of the MR-1@FeO/C system under composite pollution.