水产养殖水体附着生物对磺胺甲恶唑胁迫响应及其降解效应

研究通过模拟养殖水体,探究附着生物对磺胺甲恶唑(SMX)的胁迫响应及其对SMX的降解途径。结果表明,在5和10 mg/L SMX胁迫下,附着生物胞外聚合物(EPS)分泌较对照组增加31.3%和21.5%,抗氧化能力降低20.6%和31.8%,但生物量的积累没有显著差异。SMX使附着生物抗氧化系统受到损伤,并刺激其分泌更多胞外聚合物以提高耐受性。去除实验结果表明,附着生物会促进SMX的消减, 1 g/L附着生物在第14天对SMX的去除率为25.10%。主要降解中间产物有N4-乙酰基-磺胺甲恶唑(TP295)、对苯醌亚胺(TP107)、去砜基磺胺甲恶唑(TP189)和去氨基磺胺甲恶唑(TP238),键的断裂和苯环上氨基反应是SMX降解的两种主要途径。研究结果对评估SMX在养殖水体中的生态风险和利用附着生物去除SMX提供技术支撑。

RESPONSE OF PERIPHYTON IN AQUACULTURE WATER TO SULFAMETHOXAZOLE STRESS AND ITS DEGRADATION

The extensive use and accumulation of sulfamethoxazole (SMX) in the aquaculture contributed to its residues in aquaculture water, which may cause various negative impacts on the aquatic ecological environment. Furthermore, periphyton is a common micro-ecosystem in water bodies composed of autotrophs and heterotrophs, including algae, fungi, bacteria, protozoa, metazoans, extracellular polymers (EPS) and debris, etc. Nevertheless, there is a lack of research on the impact of SMX on the growth and development of periphyton and its purification function in aquaculture water. In this survey, the effect of SMX on periphyton was researched in simulating aquaculture water, and the response of periphyton to SMX was explored through the biomass and total antioxidant capacity of the periphyton. The removal effect and the main degradation intermediates of SMX by periphyton were investigated by high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography quadrupole-time-of-flight mass spectrometry (UPLC-QTOF-MS). This research demonstrated that under 5 and 10 mg/L SMX, the secretion of extracellular polymer (EPS) of the periphyton increased by 31.3% and 21.5% compared with the control group, and the antioxidant capacity diminished by 20.6% and 31.8%, but there was no significant difference in biomass accumulation. It showed that SMX decreased the total antioxidant capacity of the mature periphyton, their oxidative systems were damaged, and more extracellular polymers were secreted to enhance tolerance to SMX. The results of the removal experiment indicated that the periphyton would promote the reduction of SMX, and the removal rate of SMX at 1 g/L was 25.10% on the 14th day. It is supposed that SMX was used by periphyton as a carbon source to promote biodegradation and shorten the half-life of SMX degradation. Thus, periphyton had a certain potential for SMX bioremediation in aquaculture water. The main routes of SMX biodegradation by the periphyton are the cleavage and activation of the sulfonamide group (N-S bond) and the amine group (-NH₂) on the benzene ring. The primary degradation intermediates were N4-acetyl-SMX, p-Benzoquinoneimine, Desulphone-SMX and Desamino-SMX. Among these degradation products, N4-acetyl-SMX, p-Benzoquinoneimide and Desamino-SMX were fewer toxic than SMX, and Desulphone-SMX was somewhat more toxic than SMX. The research provides theoretical support for assessing the ecological risk of SMX in aquaculture water and the engineering application of periphyton to remove SMX.