Isolation And Identification Of Buprofezin-degrading Strain RX-3: Metabolic Pathway And Construction Of A Genetically Engineered Bacterium

Buprofezin is a new insecticide growth regulator that disrupts the development of immature forms by interference with chitin synthesis.Due to the intensive use of buprofezin in agriculture,their improper storage and its adverse effects makes them hazardous.Its treatment and disposal has emerged as an important environmental concern.Microbial metabolism is the main mechanism responsible for degradation of buprofezin in enviroment,although it can also be degraded through chemical and physical processes.Microorganisms play an important role in pollution treatment.Buprofezin can be used as carborn source by microorganisms.However,only five strains capable of degrading buprofezin have been documented,and the degradative pathway of buprofezin in these bacteria have received little.The soil samples were collected from a buprofezin-manufacturing factory added to 100 mL MM medium(with buprofezin)at 30 °C with shaking at 160 rpm min-1.After enrichment and purification,three transfers,4 isolates which tested positive were captured.The isolate RX-3 was considered for other tests and further characterized because of its high degrading activity.The bacterial stain RX-3 is most similar to Rhodococcus sp.based on its morphological,physiologica and biochemical characteristics,as well as phylogenetic placement inferred from 16 S rRNA gene sequence.The optimum growth temperature and pH of strain RX-3 is respectively 30 °C and 7.0.It could 98.01 percent of buprofezin(60 mg L-1)within64 h.It could also degrade buprofezin in the presence of heavy metals including Ba2+,Zn2+,Cu2+and so on.Buprofezin and metabolites were extracted with an equal volume of dichloromethane.The metabolites during buprofezin biodegradation werecaptured by as chromatography-mass spectrometryg(GC-MS).Nine degradation characteristics of buprofezin by the isolated strain were evaluated by GC-MS and a novel buprofezin-degrading pathway was also proposed.The first step in the degradation pathway of buprofezin is to form Compound B with the heterocyclic ring opend by hydrolysis.The step B in the transformation pathway of buprofezin was the sequential loss of N-tert-butyl,N-isopropyl,hydrolysis and redox reaction.methyl.Remove benzenic ring from buprofezin is the step C in the transformation pathway of buprofezin.In this study we get a fusant from the buprofezin degration strain and the chlorpyrifos degradation strain by polyethylene glycol 4000.