Isolation, Degradation Characters And Cooperating Metabolism Studies Of Cypermethrin Degrading-Bactrium Strains CDT3, PBM11

Pyrethroids pesticides are synthetic, analogy of natural pyrethrum compounds. Cypermethrin is a kind of pyrethroid, cypermethrin has low toxicity, but adequate stability in hot and light, so it has long half-life and difficult to degrade fast. There are a lot of residue in soil and crops, it is a great threat to people's health. The bioremediation technology is the main method applied in pesticide degradation since it has the advantages of safety, high efficiency and no second pollution. The bioremediation is also convention and inexpensive.A cypermethrin degrading-bacterium CDT3 was isolated from the sludge of pesticide factory, which was identified as Rhodococcus sp. by its physiology charactertics and blast its 16SrDNA in GeneBank. CDT3 can degrade cypermethrin and produce metabolites. CDT3 can transform 84.24% 100mg/L cypermethrin within 72h in flask. The optimal temperature and pH for CDT3 degrading cypermethrin is 30 ℃, pH8.0, indifferently. CDT3 can degrade 200mg/L cypermethrin, which was the highest concentrtion of prothriods degraded by single bacterium. CDT3 can't grow with cypermethrin and it degrades cypermethrin by commetabolism. Adding a little glucose, trypton, yeast extract can improve the degrading ability of CDT3. The degradation rate is 68.94% in plot test of tea. The metabolic pathway of cypermethrin degraded by CDT3 was studied. Analyzed by GC-MS, the metabolites of cypermethrin are 3-PBA (3-Phenoxybenzoic acid) and DCVA [cis, trans-3-(2,3-dichloroethenyl)-2,2- Dimethylcyclopropane-carboxylate]. It suggests that the cypermethrin-degrading is catalyzed by esterase from CDT3.A 3-Phenoxybenzoic acid degrading-bacterium PBM11 was isolated from the sludge of a pesticide plant, which was identified as Pseudomonas sp. on the basis of its morphological and biochemical properties and by 16S rDNA alignment in GeneBank. PBM11 can grow on 3-PBA as the sole carbon source. Cypermethrin can be completely degraded by combination of CDT3 and PBM11. PBM11 can mineralize 200mg/L 3-PBA within 24h under the condition of pH7.0, 30℃. Adding...