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.

在这项研究中，我们评估了林可霉素（LIN）和三种氟喹诺酮抗生素（FQs），环丙沙星（CFX），诺氟沙星（NFX）和氧氟沙星（OFX）的生物转化机制，它们通过人的活动通过不同的氨水定期进入水生环境。 -氧化微生物（AOM）。这些生物包括完全氨氧化剂（comammox）Nitrospira inopinata的纯培养物，氨氧化古细菌（AOA）Nitrososphaera gargensis和氨氧化细菌（AOB）Nitrosomonasnitroosa的纯培养物。Nm90。通过纯微生物培养物去除这些抗生素以及蛋白质归一化的生物转化速率常数表明，LIN被AOA和comammox显着地共代谢生物转化，而AOB则没有。CFX和NFX被AOA和AOB显着共代谢，但不被comammox代谢。所测试的培养物均未有效转化OFX。通常，AOA对LIN和FQ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理。i）AOA对LIN进行羟基化，S-氧化和去甲基化，以及对CFX和NFX的哌嗪部分进行亚硝化和裂解。ii）AOB利用亚硝化作用来生物转化CFX和NFX；iii）comammox进行了羟基化，去甲基化，和LIN的去甲硫基化。羟胺是氨氧化的中间体，它与LIN和选定的FQs化学反应，去除率超过90％。总的来说，这些发现提供了重要的基本见解，以了解硝化环境（包括废水处理系统）中不同氨氧化剂及其中间体对LIN和FQ生物转化的作用。