Isolation, Identification, Degradation Characters And Application Of Synthetic Pyrethroid-Degrading Bacteria

Synthetic pyrethroids (SPs) which ranks the second insecticides and account for 20% of the world insecticide market, cover up about one third in our country. Bifenthrin is a kind of a synthetic pyrethroid pesticide, which is widely used in controlling pests in tea and vegetable crops. Bifenthrin exhibit high insecticidal activity with low mammalian toxicity; however, it has an extremely high toxicity to the aquatic environment. Extensive and long term usage has draw much public concern on its residues and harmful effects. Biodegradation plays an important role in the treatment of remained pesticide.This article is study on the highly-effective-Bifenthrin-degradation strains. We will investigate its degradation properties and its application on the soil and vegetables. All of those are follows:1. This experiment was laid out using contaminated soil as the source of the strains. The inorganic salt medium with bifenthrin as the sole carbon source was used to screen the strains. After domestication cultivation, separation and purification, A single strain that can degrade befenthrin effectively was screen out. In this experiment, a bacterial strain which can degrade bifenthrin, was isolated from the polluted soil samples collected from the pesticide factory in Zhe jiang. This bacterial, which named as LBK1 was primarily identified as Bacillus Subtilis according to its physiological & biochemical characters and 16S rDNA sequence analysis.2. Analyze the degradation and growth curve of the target strains incubating in the inorganic medium containing bifenthrin. In order to optimize the culture conditions of the target strains, the degradation characteristics of target strain were studied. The optimal conditions for the degradation of bifenthrin by the LBK1 was pH 7.0, temperature 30℃, 100mg/L concentration of bifenthrin and 50ml liquid volume. Orthogonal test shows that the best degrading condition was pH 7.0, temperature 30℃, 50ml liquid volume and 5% LBK1 bacteria inoculums, under this condition the degradation rate was 95.92 %.3. On the basis of the biological research, the application of LBK1 in the soil and vegetables leaves was studied. The degrading rate of bifenthrin by strain LBK1 was tested to be 80.02% in the vegetables experiment. And the soil experiment show the co-effect of the various bacteria.