| Hexaflumuron was developed and produced by the U.S. Dow Agro Sciences in 1987, which is an efficient, broad-spectrum, low toxicity of benzoyl urea insecticides, chitin synthesis inhibitors, by inhibiting the synthesis of chitin killed Pests. It is the alternative species of the highly toxic organophosphate pesticide required of the China Pesticide Industry, "fifth"development plan,which was made by the National Petrochemical Bureau and the Ministry of Agriculture of China.Hexaflumuron is widely used in vegetables, cotton and fruit trees pest control, and plant diseases caused by fungus. However, in crops the incorrect usage also can cause phytotoxicity.At the same time hexaflumuron is toxic to fish and silkworm.The current study focused on the efficacy hexaflumuron, insecticidal effect, and toxicity of pesticide residues and degradation in soil dynamics. For the isolated pure strain degradation of hexaflumuron rarely reported, and there is no metabolic pathway and enzymes of their research.A hexaflumuron-degrading bacterium, FLN-7 was isolated from activated sludge collected from the wastewater treatment system of a pesticide factory. Based on the analysis of its 16S rDNA, morphology and physiological characteristics, strain FLN-7 was identified as Paracoccus (GenBank Accession No. EU725799). This strain could degrade 89% of 50 mg·L-1 hexaflumuron within 7 days. The partial metabolic pathway was deduced by the method of HPLC and MS analysis is the breakage of an amide bond.A amidase gene, amiH was cloned from hexaflumuron-degrading strain Paracoccus sp. FLN-7 by constructing genomic DNA library. The gene contained an open reading frame of 1395bp encoding for a protein of 465 amino acids. The G+C mol%content was 67.81%. The amiH was ligased into the expression vector pET29a and overexpressed in E.coli BL21 (DE3).Degradation experiment demonstrated that AmiH was able to hydrolyse hexaflumuron,propanil,dimethoate,chlorpropham,formamide,acetamide,propionamide,acrylamide,benzamide and urea. |
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