National Key Laboratory of Agricultural Microbiology, College of Life Science and Technology, Huazhong Agricultural University, Wuhan 430070, China.
Guangdong Provincial Key Laboratory of Conservation and Precision Utilization of Characteristic Agricultural Resources in Mountainous Areas, School of Life Sciences, Jiaying University, Meizhou 514015, China.
J Hazard Mater. 2023 Aug 15;456:131657. doi: 10.1016/j.jhazmat.2023.131657. Epub 2023 May 18.
Oxidative degradation can effectively degrade aromatic emerging contaminants (ECs). However, the degradability of lone inorganic/biogenic oxides or oxidases is typically limited when treating polycyclic ECs. Herein, we report a dual-dynamic oxidative system comprising engineered Pseudomonas and biogenic Mn oxides (BMO), which completely degrades diclofenac (DCF), a representative halogen-containing polycyclic EC. Correspondingly, recombinant Pseudomonas sp. MB04R-2 was constructed via gene deletion and chromosomal insertion of a heterologous multicopper oxidase cotA, allowing for enhanced Mn(II)-oxidizing activity and rapid formation of the BMO aggregate complex. Additionally, we characterized it as a micro/nanostructured ramsdellite (MnO) composite using multiple-phase composition and fine structure analyses. Furthermore, using real-time quantitative polymerase chain reaction, gene knockout, and expression complementation of oxygenase genes, we demonstrated the central and associative roles of intracellular oxygenases and cytogenic/BMO-derived free radicals (FRs) in degrading DCF and determined the effects of FR excitation and quenching on the DCF degradation efficiency. Finally, after identifying the degraded intermediates of H-labeled DCF, we constructed the DCF metabolic pathway. In addition, we evaluated the degradation and detoxification effects of the BMO composite on DCF-containing urban lake water and on biotoxicity in zebrafish embryos. Based on our findings, we proposed a mechanism for oxidative degradation of DCF by associative oxygenases and FRs.
氧化降解可以有效地降解芳香族新兴污染物（ECs）。然而，当处理多环 ECs 时，单一的无机/生物源氧化物或氧化酶的降解能力通常有限。在此，我们报告了一个由工程 Pseudomonas 和生物源 Mn 氧化物（BMO）组成的双重动态氧化系统，该系统可完全降解双氯芬酸（DCF），一种代表性的含卤素多环 EC。相应地，通过基因缺失和异源多铜氧化酶 cotA 的染色体插入构建了重组 Pseudomonas sp. MB04R-2，从而提高了 Mn(II)-氧化活性和 BMO 聚集体复合物的快速形成。此外，我们通过多相组成和精细结构分析将其表征为微/纳米结构的拉姆斯代尔（MnO）复合材料。此外，通过实时定量聚合酶链反应、基因敲除和加氧酶基因的表达互补，我们证明了细胞内加氧酶和细胞遗传学/BMO 衍生的自由基（FRs）在降解 DCF 中的中心和关联作用，并确定了 FR 激发和猝灭对 DCF 降解效率的影响。最后，在鉴定出 H 标记的 DCF 的降解中间产物后，我们构建了 DCF 的代谢途径。此外，我们评估了 BMO 复合材料对含 DCF 的城市湖水的降解和解毒效果以及对斑马鱼胚胎的生物毒性。基于我们的发现，我们提出了一种由关联加氧酶和 FRs 氧化降解 DCF 的机制。
