State Key Laboratory of Urban Water Resource and Environment, School of Environment, Harbin Institute of Technology, Harbin 150090, China.
School of Civil & Environmental Engineering, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China.
Environ Sci Technol. 2020 Jun 16;54(12):7591-7600. doi: 10.1021/acs.est.9b07324. Epub 2020 Jun 1.
The chlorinated nitroaromatic antibiotic chloramphenicol (CAP) is a refractory contaminant that is widely present in various environments. However, few CAP-mineralizing bacteria have been documented, and a complete CAP catabolism pathway has yet to be identified. In this study, the bacterial strain sp. CAP-1 was isolated from an activated sludge sample and was shown to be capable of aerobically subsisting on CAP as the sole carbon, nitrogen, and energy source while simultaneously and efficiently degrading CAP. -Nitrobenzoic acid (PNBA), -nitrobenzaldehyde (PNBD), protocatechuate (PCA), and the novel side chain C-hydroxy-oxygenated product of CAP (O-CAP) were identified during CAP degradation. Strain CAP-1 was able to convert O-CAP to intermediate product PNBA. The putative functional genes associated with PNBA catabolism into the tricarboxylic acid cycle via PCA and floc formation were also identified by genome sequencing and comparative proteome analysis. A complete pathway for CAP catabolism was proposed. The discovery of a novel CAP oxidation/detoxification process and a complete pathway for CAP catabolism enriches the fundamental understanding of the bacterial catabolism of antibiotics, providing new insights into the microbial-mediated fate, transformation, and resistance risk of CAP in the environment. The molecular basis of CAP catabolism and floc formation in strain CAP-1 also offers theoretical guidance for the enhanced bioremediation of CAP-containing environments.
氯硝基本土霉素（CAP）是一种难处理的污染物，广泛存在于各种环境中。然而，已记录的能矿化 CAP 的细菌很少，并且尚未确定完整的 CAP 分解代谢途径。在本研究中，从活性污泥样品中分离出一株细菌 sp. CAP-1，该菌能够以 CAP 作为唯一的碳、氮和能源进行好氧生存，同时高效地降解 CAP。在 CAP 降解过程中鉴定出了 -硝基苯甲酸（PNBA）、-硝基苯甲醛（PNBD）、原儿茶酸（PCA）和 CAP 的新型侧链 C-羟基氧化产物（O-CAP）。CAP-1 菌株能够将 O-CAP 转化为中间产物 PNBA。通过基因组测序和比较蛋白质组学分析，还确定了与 PNBA 通过 PCA 代谢进入三羧酸循环和絮体形成相关的假定功能基因。提出了 CAP 分解代谢的完整途径。发现了一种新型的 CAP 氧化/解毒过程和 CAP 分解代谢的完整途径，丰富了细菌对抗生素代谢的基础认识，为环境中 CAP 的微生物介导的命运、转化和抗性风险提供了新的见解。CAP-1 中 CAP 代谢和絮体形成的分子基础也为含有 CAP 的环境的增强生物修复提供了理论指导。
