Jiangsu Key Laboratory for Microbes and Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science, Nanjing Normal University, Nanjing, People's Republic of China.
The Key Laboratory of Biotechnology for Medicinal Plants of Jiangsu Province and School of Life Science, Jiangsu Normal University, Xuzhou, People's Republic of China.
J Appl Microbiol. 2021 Dec;131(6):2838-2848. doi: 10.1111/jam.15172. Epub 2021 Jun 23.
Aims of this study are to elucidate the molecular mechanism of copper-improved thiacloprid (THI) degradation by Ensifer adhaerens TMX-23 and characterize copper resistance of this strain.
Resting cells of E. adhaerens TMX-23 were used to degrade THI, with formation of THI amide and 98·31% of 0·59 mmol l THI was degraded in 100 min. The addition of copper improved the degradation of THI and showed little inhibitory effects on the growth of E. adhaerens TMX-23. E. adhaerens TMX-23 degraded THI to THI amide by nitrile hydratases (NhcA and NhpA). QPCR analysis indicated that the expression of nhpA was up-regulated in the presence of copper. E. adhaerens TMX-23 nitrile hydratases were purified, and enzyme assay of NhpA exhibited the highest NHase activity toward THI. The addition of copper activated the activity of NhcA. Soil degradation experiment indicated that E. adhaerens TMX-23 could quickly eliminate THI residual in copper-added soil.
Copper improved THI degradation by E. adhaerens TMX-23 was attributed to the induced expression of nhpA and activated NhcA.
This study broadens the investigation of regulatory mechanism of NHase expression and provided theoretical basis for using metal-resistant microbes to degrade pesticide in heavy metal co-contaminated environments.
本研究旨在阐明铜增强噻虫啉（THI）降解的分子机制，以及研究土壤杆菌 TMX-23 对铜的抗性。
使用土壤杆菌 TMX-23 的休眠细胞来降解 THI，在 100 分钟内形成 THI 酰胺，并且 0.59mmol/L 的 THI 有 98.31%被降解。铜的添加提高了 THI 的降解效率，对土壤杆菌 TMX-23 的生长几乎没有抑制作用。土壤杆菌 TMX-23 通过腈水解酶（NhcA 和 NhpA）将 THI 降解为 THI 酰胺。QPCR 分析表明，铜存在时 nhpA 的表达上调。土壤杆菌 TMX-23 的腈水解酶被纯化，酶活性测定表明 NhpA 对 THI 表现出最高的 NHase 活性。铜的添加激活了 NhcA 的活性。土壤降解实验表明，土壤杆菌 TMX-23 能够迅速消除添加铜的土壤中的 THI 残留。
铜增强土壤杆菌 TMX-23 对 THI 的降解归因于 nhpA 的诱导表达和 NhcA 的激活。
本研究拓宽了 NHase 表达调控机制的研究，为利用金属抗性微生物在重金属复合污染环境中降解农药提供了理论依据。
