School of Civil and Environmental Engineering, Nanyang Technological University, 639798, Singapore; Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore.
Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 637141, Singapore.
Water Res. 2019 Feb 1;149:432-439. doi: 10.1016/j.watres.2018.10.031. Epub 2018 Oct 13.
The sulfonamide antibiotics sulfamethoxazole (SMX) has been frequently detected in the wastewater. It has been reported that part of SMX can be transformed by the co-metabolism of ammonia oxidizing bacteria (AOB) during nitrifying process. However, previous studies reported inconsistent or even contradictory results in terms of SMX degradation and/or transformation. Literature study revealed that nitrite may play certain role in SMX transformation, which has been neglected previously. In this study, the transformation behavior of SMX was investigated with and without the presence of nitrite in an enriched nitrifying culture. The results clearly show that the elimination of SMX occurred with the presence/accumulation of nitrite, and a linear regression was observed between SMX elimination efficiency and free nitrous acid (FNA) concentration, indicating that FNA was the major factor responsible for the SMX transformation. By reacting with FNA, SMX transformation products, such as 4-nitro-SMX, desamino-SMX and hydroxylated SMX, were detected. However, when FNA concentration decreased, these intermediates may be retransformed back to SMX. These findings improved our understanding on SMX transformation in a biological system and highlighted the role of nitrite/FNA in the sulfonamide antibiotics degradation.
磺胺类抗生素磺胺甲恶唑（SMX）经常在废水中被检测到。据报道，部分 SMX 可以在硝化过程中被氨氧化细菌（AOB）的共代谢转化。然而，之前的研究在 SMX 降解和/或转化方面报告了不一致甚至矛盾的结果。文献研究表明，亚硝酸盐可能在 SMX 转化中起一定作用，但之前被忽视了。在这项研究中，在富硝化培养物中存在和不存在亚硝酸盐的情况下，研究了 SMX 的转化行为。结果清楚地表明，SMX 的消除伴随着亚硝酸盐的存在/积累，并且观察到 SMX 消除效率与游离亚硝酸（FNA）浓度之间存在线性关系，表明 FNA 是导致 SMX 转化的主要因素。通过与 FNA 反应，检测到 SMX 转化产物，如 4-硝基-SMX、去氨基-SMX 和羟基化 SMX。然而，当 FNA 浓度降低时，这些中间体可能会重新转化回 SMX。这些发现提高了我们对生物系统中 SMX 转化的理解，并强调了亚硝酸盐/FNA 在磺胺类抗生素降解中的作用。
