Isolation, Identification&Characterization Of Beta-Cypermethrin Degrading Bacteria

Synthetical pyrethroids (SPs) are a class of synthetic imitation of natural pyrethroid pesticide, it is more safety to human and animal than the organochlorine and organophosphorus pesticides, and widely used in agricultural and house formulation. Recent studies show that it is highly toxic to some non-target organisms, such as bees, silkworm, fish. And human being and other mammals exposure to SPs maight cause damage to the nervous, immune, and endocrine systems This study intends to isolation of the beta-cypermethrin degrading bacteria, and then characteristion of the bacteria, at last study its application in soil remediation.Five novels strain were isolated from the activated sludge of a pesticide manufacturer in Shang Yu, which was capable of degrading beta-cypermethrin (beta-CP), and strain HZ5was most active.Based on its physiological characteristics and analysis of16S rDNA gene, strain HZ5was identified as Azoarcus indigens. Strain HZ5could degrade beta-CP over a wide range of temperature (20to40℃) and pH (5.5to9.0), and the optimal temperature and pH were30℃and7.0. The highest degradation rate was approximately70%of50mg/1beta-CP within144h at pH7.0and30℃in MSM. Additional carbon source could enhance the biodegradation of beta-CP. Studies on biodegradation the enantiomers of beta-CP showed no significant enantioselectivity.During the process, two main intermediate metabolites were produced by strain HZ5and determined as3-phenoxybenzaldehyde and3-phenoxybenzoic acid by gas chromatography-mass spectrometry (GC-MS) analysis.Soil bioremediation experiment showed strain HZ5could remove91.7%of beta-CP from the soil and accelerate the degradation of beta-CP significantly. The results indicated that strain HZ5may have potential application in bioremediation of beta-CP polluted environment.