Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China; SynBio Research Platform, Collaborative Innovation Centre of Chemical Science and Engineering (Tianjin), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China.
Frontiers Science Center for Synthetic Biology and Key Laboratory of Systems Bioengineering (Ministry of Education), School of Chemical Engineering and Technology, Tianjin University, Yaguan Road 135, Jinnan District, Tianjin 300350, PR China.
Sci Total Environ. 2021 Sep 1;785:147379. doi: 10.1016/j.scitotenv.2021.147379. Epub 2021 Apr 27.
Fluoroquinolones (FQs), such as ciprofloxacin (CIP) and norfloxacin (NOR), are types of emerging trace pollutants that have attracted great attention. In this study, an activated sludge (AS) consortium with high bio-removal capability to CIP and NOR was obtained by acclimating with CIP and NOR for 10 d. Meanwhile, a CIP- and NOR- transforming bacterial strain (S5), which is highly homologous to the 16S rRNA gene sequence of Enterobacter sp., was isolated from the acclimated AS. The bio-removal efficiency of CIP under the acclimated AS consortium was better than that under the pure culture of Enterobacter sp. S5 (93.1% vs. 89.3%), while the bio-removal efficiency of NOR under the acclimated AS consortium was lower than that under the pure culture of Enterobacter sp. S5 (83.9% vs. 89.8%). The biotransformation and bio-adsorption were two main ways to bio-remove CIP and NOR. However, the CIP and NOR biotransformation efficiencies of the acclimated AS were higher than under the pure culture of Enterobacter sp. S5, while the CIP and NOR adsorption of acclimated AS were lower than that under the pure culture of Enterobacter sp. S5. The N-acetylciprofloxacin and N-acetylnorfloxacin were the main biotransformation products of CIP and NOR. It is possible that acetyltransferase may be involved in the biotransformation process. Whether under the pure culture or AS consortium, the cytotoxicity of CIP and NOR transformation products to gram-negative bacteria was alleviated. Therefore, the acclimated AS and Enterobacter sp. S5 might provide a new strategy for removing contaminants and alleviating of FQs resistance.
氟喹诺酮类（FQs），如环丙沙星（CIP）和诺氟沙星（NOR），是一类新兴的痕量污染物，引起了极大关注。在这项研究中，通过用 CIP 和 NOR 驯化 10 d 获得了具有高生物去除 CIP 和 NOR 能力的活性污泥（AS）共混物。同时，从驯化的 AS 中分离出一株与肠杆菌属 16S rRNA 基因序列高度同源的 CIP 和 NOR 转化细菌菌株（S5）。在驯化的 AS 共混物中，CIP 的生物去除效率优于肠杆菌属 S5 的纯培养物（93.1%对 89.3%），而 NOR 的生物去除效率低于肠杆菌属 S5 的纯培养物（83.9%对 89.8%）。生物转化和生物吸附是生物去除 CIP 和 NOR 的两种主要方式。然而，驯化的 AS 中 CIP 和 NOR 的生物转化效率高于肠杆菌属 S5 的纯培养物，而 CIP 和 NOR 的驯化 AS 吸附率低于肠杆菌属 S5 的纯培养物。N-乙酰基环丙沙星和 N-乙酰基诺氟沙星是 CIP 和 NOR 的主要生物转化产物。可能涉及乙酰转移酶参与生物转化过程。无论是在纯培养物还是 AS 共混物中，CIP 和 NOR 转化产物对革兰氏阴性菌的细胞毒性均减轻。因此，驯化的 AS 和肠杆菌属 S5 可能为去除污染物和减轻 FQs 抗性提供了一种新策略。
