Study On B-Cypermethrin Degradation By Pseudomonasaeruginosa GF31and Extracelluluar Rude Enzyme

B-cypermethrin is a synthetic and broad spectrum pyrethroid pesticide, widely used to control pests in agriculture and at home because of its strong neurotoxic activity against pests. Due to its long-term use, the β-cypermethrin residue has severely damaged the ecological environment, therefore endangering the human health. Microbial degradation β-cypermethrin is a safe and effective means of environmental restoration.According to the degradation of system characteristics, this paper established acetonitrile-inorganic salt-water aqueous two-phase extraction method of P-cypermethrin and its metabolites3-pbh and3-pba, of which the average recovery was between94.8%-98.3%and the variance coefficient was between2.11～3.15. Compared to literature methods, the advantages of our methodology are easy work-up, high reproducibility and precision.The strain Pseudomonas aeruginosa GF31, which was isolated and preserved in the lab, was used to research the characteristics of the bacteria degrading β-cypermethrin. The strain GF31could not use β-cypermethrin as a sole carbon and nitrogen source. Under the condition of no nutrition, the GF31strain degraded β-cypermethrin slowly, which was due to enzymatic degradation of extracellular enzymes from the released cells. A special inducer was not needed for the extracellular enzymes from strain GF31to degrade β-cypermethrin, which means that the degradation enzymes were constitutive enzymes, produced conditions of β-cypermethrin degradation enzyme by Strain GF31were optimized primarily in this thesis.This paper studies the added-nutrition effect of Pseudomonas aeruginosa GF31degrading β-cypermethrin. It is found that the medium which contained different kinds of carbon and nitrogen source and different C/N could affect the efficiency of β-cypermethrin degradation by strain GF31. When containing C/N=3:1mannitol and ammonium sulfate (N1g·L-1) in the medium, the degradation rate was highest, which is46.4%. Excessive addition of nutrition would lead the formation of catabolite, which would cause the reduction of the pH level, meanwhile, the degradation efficiency would be declined. There is no positive correlation between the amount of bacteria and degradation efficiency.By the instrumental method of HPLC, it was found that strain GF31could degrade β-cypermethrin during the hydrolysis process to produce3-Phenoxybenzaldehyde, then3-Phenoxybenzaldehyde would be translated into3-Phenoxybenzoic acid.