Bioremediation of Environmental Neonicotinoids Thiamethoxam and Clothianidin Contamination: Ecological Toxicity, Microbial Resources, Degradation Pathways, and Associated Enzymes

The chlorothiazolyl neonicotinoid insecticides thiamethoxam (THX) and clothianidin (CLO) are used widely in modern agriculture. However, their frequent application results in inevitable contamination of soil and water environments, posing potential ecological risks and threats to human health. Microbial remediation is an effective and environmentally friendly approach to addressing this issue. Some THX- and CLO-degrading microorganisms have been isolated and characterized, but their degradation mechanisms are not systematically reviewed. This review describes the environmental residues of THX and CLO, and their potential ecological toxicities toward terrestrial and aquatic ecosystems. Especially, the focus was paid to the degradation microorganisms and degradation pathways of THX and CLO, discussing the associated metabolic enzymes, including cytochrome P450 enzymes and aldehyde oxidases. This review deepens our understanding on microbial degradation mechanisms of THX and CLO, and provides theoretical and practical bases for the bioremediation of environmental THX and CLO contamination.