Extracellular electron transfer-enhanced sulfamethoxazole biodegradation: Mechanisms and process strengthening

Antibiotics like Sulfamethoxazole (SMX) pose a significant threat to public health and environmental well-being. To address this issue, effective strategies are being developed to remove antibiotics from the environment. This study investigates the degradation of SMX with a focus on elucidating the mechanism by which extracellular electron transfer (EET) enhances the efficient degradation of the antibiotic. The results show that SMX was significantly degraded (97 %) by Shewanella oneidensis MR-1 after 120 hours in the presence of a bioelectrochemical system (BES) at a concentration of 1 mg L⁻¹, compared to the absence of BES (69 %) at the same concentration and time. BES was observed to simultaneously remove pollutants like SMX while generating electricity at this concentration. Proteomic analysis was further employed to clarify the mechanism behind this process. Three key SMX-degrading proteins; S-ribosylhomocysteine lyase (luxS), Deoxyribose-phosphate aldolase (deoC), and Amidohydrolase which mainly participated in C-S cleavage, S-N hydrolysis and isoxazole ring cleavage were identified. The study demonstrates that S. oneidensis MR-1 can promote the generation of Nicotinamide Adenine Dinucleotide and Adenosine Triphosphate and facilitate electron transfer to enhance the efficient degradation of SMX. The findings of this study provide new insights into the correlation mechanism between SMX degradation and EET, ultimately contributing to innovative solutions for environmental remediation.