Advanced Water Management Centre, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia.
School of Civil and Environmental Engineering, University of Technology Sydney, Ultimo, NSW 2007, Australia.
Environ Pollut. 2019 Dec;255(Pt 1):113160. doi: 10.1016/j.envpol.2019.113160. Epub 2019 Sep 4.
The intensive use of antibiotics results in the continuous release of antibiotics into wastewater treatment systems, leading to the spread of antibiotic resistance. Nitrifying system is reported to be capable of degrading antibiotics, yet few studies have systematically investigated the inherent correlation among ammonium oxidation rate, antibiotic degradation and genetic expression of nitrifying bacteria along the process. This study selected a widely used sulfonamide antibiotic, sulfadiazine (SDZ), to investigate its biodegradation potential by an enriched nitrifying culture and the response of nitrifying bacteria against antibiotic exposure. Our results demonstrated that SDZ degradation was mainly contributed by cometabolism of ammonia-oxidizing bacteria (AOB), rather than biomass adsorption. The quantitative reverse transcription PCR (RT-qPCR) analysis revealed that the expression level of amoA gene was down-regulated due to the SDZ exposure. In addition, the degradation products of SDZ did not exhibit inhibitory effect on Escherichia coli K12, indicating the biotoxicity of SDZ could be mitigated after biodegradation. The findings offer insights regarding the biodegradation process of sulfonamide antibiotics via cometabolism by AOB.
抗生素的大量使用导致抗生素不断释放到废水处理系统中，从而导致抗生素耐药性的传播。据报道，硝化系统能够降解抗生素，但很少有研究系统地调查沿过程的氨氧化速率、抗生素降解和硝化细菌遗传表达之间的内在相关性。本研究选择了一种广泛使用的磺胺类抗生素磺胺嘧啶（SDZ），通过富集硝化培养物来研究其生物降解潜力，以及硝化细菌对抗生素暴露的反应。我们的结果表明，SDZ 的降解主要是由氨氧化细菌（AOB）的共代谢贡献的，而不是生物质吸附。定量逆转录 PCR（RT-qPCR）分析显示，由于 SDZ 的暴露，amoA 基因的表达水平下调。此外，SDZ 的降解产物对大肠杆菌 K12 没有表现出抑制作用，表明 SDZ 的生物毒性在生物降解后可以减轻。这些发现为通过 AOB 共代谢对磺胺类抗生素的生物降解过程提供了深入了解。
