title: Degradation of the neonicotinoid insecticide acetamiprid via the N-carbamoylimine derivate (IM-1-2) mediated by the nitrile hydratase of the nitrogen-fixing bacterium Ensifer meliloti CGMCC 7333.
abstract: The metabolism of the widely used neonicotinoid insecticide acetamiprid (ACE) has been extensively studied in plants, animals, soils, and microbes. However, hydration of the N-cyanoimine group in ACE to the N-carbamoylimine derivate (IM-1-2) by purified microbes, the enzyme responsible for this biotransformation, and further degradation of IM-1-2 have not been studied. The present study used liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy to determine that the nitrogen-fixing bacterium Ensifer meliloti CGMCC 7333 transforms ACE to IM-1-2. CGMCC 7333 cells degraded 65.1% of ACE in 96 h, with a half-life of 2.6 days. Escherichia coli Rosetta (DE3) overexpressing the nitrile hydratase (NHase) from CGMCC 7333 and purified NHase converted ACE to IM-1-2 with degradation ratios of 97.1% in 100 min and 93.9% in 120 min, respectively. Interestingly, IM-1-2 was not further degraded by CGMCC 7333, whereas it was spontaneously hydrolyzed at the N-carbamoylimine group to the derivate ACE-NH, which was further converted to the derivative ACE-NH2. Then, ACE-NH2 was cleaved to the major metabolite IM-1-4. IM-1-2 showed significantly lower insecticidal activity than ACE against the aphid Aphis craccivora Koch. The present findings will improve the understanding of the environmental fate of ACE and the corresponding enzymatic mechanisms of degradation.
authors.affiliation: 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 210023, People's Republic of China.
authors.forename: Ling-Yan
authors.initials: LY
authors.lastname: Zhou
authors.forename: Long-Jiang
authors.initials: LJ
authors.lastname: Zhang
authors.forename: Shi-Lei
authors.initials: SL
authors.lastname: Sun
authors.forename: Feng
authors.initials: F
authors.lastname: Ge
authors.forename: Shi-Yun
authors.initials: SY
authors.lastname: Mao
authors.forename: Yuan
authors.initials: Y
authors.lastname: Ma
authors.forename: Zhong-Hua
authors.initials: ZH
authors.lastname: Liu
authors.forename: Yi-Jun
authors.initials: YJ
authors.lastname: Dai
authors.forename: Sheng
authors.initials: S
authors.lastname: Yuan
mesh_terms: D000818:Animals; D001042:Aphids / Q000187:drug effects; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001711:Biotransformation; D006207:Half-Life; D006836:Hydro-Lyases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D015394:Molecular Structure; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000737:chemistry / Q000378:metabolism / Q000633:toxicity; D009586:Nitrogen Fixation; D011725:Pyridines / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D012230:Rhizobiaceae / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D011725:Pyridines; C464485:acetamiprid; D006836:Hydro-Lyases; C048831:nitrile hydratase
keywords: Ensifer meliloti; IM-1-2; acetamiprid; bioefficacy; hydration; nitrile hydratase