Enhancing malathion degradation by Shewanella oneidensis MR-1 through FeO/C optimization: Insights from response...

This study investigated the characteristics and mechanisms underlying malathion degradation by Shewanella oneidensis MR-1 (S. oneidensis MR-1). Through a combination of single-factor experiments and response surface methodology, the optimal degradation conditions were identified as follows: as a malathion concentration of 30 mg/L, a temperature of 35 °C, and a pH of 7, under which the degradation rate exceeded 90 %. Further optimization of the FeO/C composite system revealed the following optimal parameters: an initial malathion concentration of 51.3 mg/L, a reaction time of 3.7 day, an inoculum volume of 1 % (v/v), and an FeO/C material dosage of 0.1 g/L. LCMS/MS analysis enabled the identification of various intermediates during malathion degradation. Metabolomics analysis revealed that exposure to malathion enhanced the lipid, vitamins and cofactors metabolism of S. oneidensis MR-1, with FeO/C supplementation further elevating these metabolic responses. In particular, the accumulation of palmitic acid and nicotinamide was correlated with enhanced cellular stress resistance. These findings provide a theoretical basis for the bioremediation of malathion-contaminated environments.