1. Enhanced biodegradation of thiamethoxam with a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar immobilized Chryseobacterium sp H5.
- Author
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Xiang, Xuezhu, Yi, Xiaohui, Zheng, Wanbing, Li, Yingqiang, Zhang, Chao, Wang, Xinzhi, Chen, Zhenguo, Huang, Mingzhi, and Ying, Guang-Guo
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NEONICOTINOIDS , *POLYVINYL alcohol , *THIAMETHOXAM , *GRAM-negative aerobic bacteria , *ENVIRONMENTAL security , *ALGINIC acid , *BIODEGRADATION - Abstract
Long-term and extensive usage of thiamethoxam, the second-generation neonicotinoid insecticide, has caused a serious threat to non-target organisms and ecological security. Efficient immobilized microorganism techniques are a sustainable solution for bioremediation of thiamethoxam contamination. A Gram-negative aerobic bacterium Chryseobacterium sp H5 with high thiamethoxam-degrading efficiencies was isolated from activated sludge. Then we developed a novel polyvinyl alcohol (PVA)/sodium alginate (SA)/biochar bead with this functional microbe immobilization to enhance the biodegradation and removal of thiamethoxam. Results indicated that the total removal and biodegradation rate of thiamethoxam with PVA/SA/biochar (0.7 %) beads with Chryseobacterium sp H5 immobilization at 30 °C and pH of 7.0 within 7 d reached about 90.47 % and 68.03 %, respectively, much higher than that using PVA/SA immobilized microbes (75.06 %, 56.05 %) and free microbes (61.72 %). Moreover, the PVA/SA/biochar (0.7 %) immobilized microbes showed increased tolerance to extreme conditions. Biodegradation metabolites of thiamethoxam were identified and two intermediates were first reported. Based on the identified biodegradation intermediates, cleavage of C-N between the 2-chlorothiazole ring and oxadiazine, dichlorination, nitrate reduction and condensation reaction would be the major biodegradation routes of thiamethoxam. Results of this work suggested the novel PVA/SA/biochar beads with Chryseobacterium sp H5 immobilization would be helpful for the effective bioremediation of thiamethoxam contamination. [Display omitted] • A novel PVA/SA/biochar immobilization carrier was developed. • A thiamethoxam-degrading bacterium Chryseobacterium sp H5 was isolated. • Microbes within PVA/SA/biochar beads showed higher tolerance to extreme conditions. • Two new biodegradation intermediates of thiamethoxam were first reported. • Cleavage of C-N, dichlorination, and nitrate reduction would be the major routes. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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