Zhou Li-Jun, Han Ping, Zhao Mengyue, Yu Yaochun, Sun Dongyao, Hou Lijun, Liu Min, Zhao Qiang, Tang Xiufeng, Klümper Uli, Gu Ji-Dong, Men Yujie, Wu Qinglong L
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing, 210008, China.
School of Geographic Sciences, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China; Institute of Eco-Chongming, East China Normal University, 3663 North Zhongshan Road, Shanghai 200062, China.
Water Res. 2021 May 15;196:117003. doi: 10.1016/j.watres.2021.117003. Epub 2021 Mar 3.
In this study, we evaluated the biotransformation mechanisms of lincomycin (LIN) and three fluoroquinolone antibiotics (FQs), ciprofloxacin (CFX), norfloxacin (NFX), and ofloxacin (OFX), which regularly enter aquatic environments through human activities, by different ammonia-oxidizing microorganisms (AOM). The organisms included a pure culture of the complete ammonia oxidizer (comammox) Nitrospira inopinata, an ammonia oxidizing archaeon (AOA) Nitrososphaera gargensis, and an ammonia-oxidizing bacterium (AOB) Nitrosomonas nitrosa Nm90. The removal of these antibiotics by the pure microbial cultures and the protein-normalized biotransformation rate constants indicated that LIN was significantly co-metabolically biotransformed by AOA and comammox, but not by AOB. CFX and NFX were significantly co-metabolized by AOA and AOB, but not by comammox. None of the tested cultures transformed OFX effectively. Generally, AOA showed the best biotransformation capability for LIN and FQs, followed by comammox and AOB. The transformation products and their related biotransformation mechanisms were also elucidated. i) The AOA performed hydroxylation, S-oxidation, and demethylation of LIN, as well as nitrosation and cleavage of the piperazine moiety of CFX and NFX; ii) the AOB utilized nitrosation to biotransform CFX and NFX; and iii) the comammox carried out hydroxylation, demethylation, and demethylthioation of LIN. Hydroxylamine, an intermediate of ammonia oxidation, chemically reacted with LIN and the selected FQs, with removals exceeding 90%. Collectively, these findings provide important fundamental insights into the roles of different ammonia oxidizers and their intermediates on LIN and FQ biotransformation in nitrifying environments including wastewater treatment systems.
在本研究中，我们评估了林可霉素（LIN）以及三种氟喹诺酮类抗生素——环丙沙星（CFX）、诺氟沙星（NFX）和氧氟沙星（OFX）的生物转化机制。这些抗生素通常通过人类活动进入水生环境，我们研究了不同的氨氧化微生物（AOM）对它们的转化情况。这些微生物包括完全氨氧化菌（comammox）意外硝化螺旋菌的纯培养物、氨氧化古菌（AOA）加尔各答亚硝化球菌以及氨氧化细菌（AOB）硝化单胞菌Nm90。通过纯微生物培养对这些抗生素的去除情况以及蛋白质标准化生物转化速率常数表明，LIN通过AOA和comammox进行显著的共代谢生物转化，但不被AOB转化。CFX和NFX被AOA和AOB显著共代谢，但不被comammox转化。所测试的培养物均未有效转化OFX。总体而言，AOA对LIN和氟喹诺酮类抗生素表现出最佳的生物转化能力，其次是comammox和AOB。还阐明了转化产物及其相关的生物转化机制。i）AOA对LIN进行羟基化、S-氧化和去甲基化，对CFX和NFX的哌嗪部分进行亚硝化和裂解；ii）AOB利用亚硝化作用对CFX和NFX进行生物转化；iii）comammox对LIN进行羟基化、去甲基化和去甲硫基化。羟胺是氨氧化的中间产物，与LIN和选定的氟喹诺酮类抗生素发生化学反应，去除率超过90%。总的来说，这些发现为不同氨氧化菌及其中间产物在包括废水处理系统在内的硝化环境中对LIN和氟喹诺酮类抗生素生物转化中的作用提供了重要的基础见解。
