Department of Environmental Science and Engineering, College of Life and Environmental Science, Shanghai Normal University , Shanghai 200234, PR China.
Swette Center for Environmental Biotechnology, Biodesign Institute, Arizona State University , Tempe, AZ 85287-5701, United States.
Environ Sci Technol. 2015 Oct 6;49(19):11536-42. doi: 10.1021/acs.est.5b03293. Epub 2015 Sep 15.
Quinoline, a recalcitrant heterocyclic compound, is biodegraded by a series of reactions that begin with mono-oxygenations, which require an intracellular electron donor. Photolysis of quinoline can generate readily biodegradable products, such as oxalate, whose bio-oxidation can generate endogenous electron donors that ought to accelerate quinoline biodegradation and, ultimately, mineralization. To test this hypothesis, we compared three protocols for the biodegradation of quinoline: direct biodegradation (B), biodegradation after photolysis of 1 h (P1h+B) or 2 h (P2h+B), and biodegradation by adding oxalate commensurate to the amount generated from photolysis of 1 h (O1+B) or 2 h (O2+B). The experimental results show that P1h+B and P2h+B accelerated quinoline biodegradation by 19% and 50%, respectively, compared to B. Protocols O1+B and O2+B also gave 19% and 50% increases, respectively. During quinoline biodegradation, its first intermediate, 2-hydroxyquinoline, accumulated gradually in parallel to quinoline loss but declined once quinoline was depleted. Mono-oxygenation of 2-hydroxyquinoline competed with mono-oxygenation of quinoline, but the inhibition was relieved when extra electrons donors were added from oxalate, whether formed by UV photolysis or added exogenously. Rapid oxalate oxidation stimulated both mono-oxygenations, which accelerated the overall quinoline oxidation that provided the bulk of the electron donor.
喹啉是一种难降解的杂环化合物，可通过一系列反应进行生物降解，这些反应首先需要单加氧作用，而单加氧作用需要细胞内电子供体。喹啉的光解可以生成易生物降解的产物，如草酸盐，其生物氧化可以生成内源性电子供体，从而加速喹啉的生物降解，并最终矿化。为了验证这一假设，我们比较了三种喹啉生物降解方案：直接生物降解（B）、光照 1 小时（P1h+B）或 2 小时（P2h+B）后的生物降解以及添加与光照 1 小时（O1+B）或 2 小时（O2+B）生成量相当的草酸盐后的生物降解。实验结果表明，与 B 相比，P1h+B 和 P2h+B 分别将喹啉生物降解加速了 19%和 50%。O1+B 和 O2+B 方案也分别增加了 19%和 50%。在喹啉生物降解过程中，其第一个中间产物 2-羟基喹啉与喹啉的损失平行逐渐积累，但一旦喹啉耗尽，其含量就会下降。2-羟基喹啉的单加氧作用与喹啉的单加氧作用竞争，但当从草酸盐（无论是通过 UV 光解形成还是外加）中添加额外的电子供体时，抑制作用就会得到缓解。草酸盐的快速氧化刺激了两种单加氧作用，从而加速了整个喹啉氧化，为大量电子供体提供了来源。
