Biotransformation of sulfamethoxazole by newly isolated surfactant-producing strain Proteus mirabilis sp. ZXY4: Removal efficiency, pathways, and mechanisms

Abstract

In this study, the SMX degrading strain Proteus mirabilis sp. ZXY4 with surfactant manufacturing potential was isolated from sludge utilizing blood agar and CTAB agar plate. FTIR analysis indicated that the biosurfactant generated by strain ZXY4 was glycolipid. 3D-EEM demonstrated that SMX biodegradation was strongly connected to biosurfactants, the synergistic effect of biodegradation and biosurfactant made strain ZXY4 have excellent SMX degradation performance. Under the optimal conditions of inoculation dosage of 15%, temperature of 30 ℃, pH of 7 and initial SMX concentration of 5 mg L-1, strain ZXY4 could completely degrade SMX within 24 h. SMX biodegrades at low concentrations (less than5 mg L-1) followed by the zero-order kinetic model, high concentration (>5 mg L-1) is more consistent with the first-order kinetic model. LC-MS analysis revealed 14 SMX degradation intermediates, and five potential biodegradation mechanisms were postulated. The findings provide new insights into the biodegradation of SMX.