Construction And Characteristics Of Beta-cypermethrin Degrading Flora In Continuous Cotton Fields Of Xinjiang

The non-point source pollution of pesticide in local soil was caused by a massive long-term cultivation of cotton in Xinjiang, and bred variety of agricultural contamination, so that the microbial resource was degraded. This study took the soil which has been used to plant the cotton continuously more than 10 a as material and the beta-cypermethrin as the sole carbon source. Frist of all, this study adopts the way of acclimating that gradually added the amount and serial passage the bacteria source, initially obtain and identify the flora that can stable passaged and continuous degraded beta-cypermethrin from soil.Secondly, isolating culturable microorganisms from degradation consortium of beta-cypermethrin by the method of dilution coating, and according to the colony morphological observation of cells, 11 culturable microbial determined preliminarily were screened from the degrading bacteria,respectively numbered as GX2-GX12. Using the wag of CTAB / Na Cl to extract bacteria DNA, primers polymerase chain reaction(PCR) technique to amplify bacterial gene fragments extracted. In addition, comparative 16 s ribosomal RNA sequence analysis was used for elucidation of bacterial identification. Through the 16 Sr RNA homologous analysis of all of the sequences, the result showed that the flora is composed of 10 strains of Pseudomonas aeruginosa and 1 strain of Achromobacter sp.. The 16 Sr DNA sequence analysis indicated that 10 strains belonged to the branch of Pseudomonas aeruginosa, with a similarity of 99%. 1 strains belonged to the branch of Achromobacter mucicolens, with a similarity of 99%. Through the sequence alignment analysis of the obtained strains, the species of culturable microorganisms that can degrade beta-cypermethrin in cotton fields soil are less. And the dominant microorganism is Pseudomonas aeruginosa strains, accounting for 90.91%. Achromobacter mucicolens strains accounted for 9.09%. Thus we infer that the degrade of cypermethrin microbes obtained in this experiment mainly are Pseudomonas aeruginosa microorganisms.Thirdly, with the initial pesticide concentrations(100, 150, 250mg/L), temperature(27, 32, 37 ℃), the initial p H(6.5, 7, 7.5), the volume of medium(100, 200, 300 m L) as experiment factors, using the orthogonal test method of four factors and three levels, to preliminary analysis the characteristic of the flora’s degradation for the beta-cypermethrin, each group were repeated twice. The test results show that the mixed bacteria has a wide adaptability to the environment, with LB culture medium to make the seed liquid, The analysis of range showed that the optimum condition is as follows: the initial pesticide concentration of 250 mg/L, the temperature of 27 ℃, the initial p H 7.5, the volume of medium of 300 m L; The result of analysis of Variance show that only more than p H is not significant factors, and the optimum condition is: the initial concentration of 250 mg/L, the temperature of 27 ℃, the volume of medium of 300 m L; measured that cultivation of 48 h degradation rate could reach 96.15%, cultivation of 144 h degradation rate could reach 84.27%, cultivation of 204 h degradation rate could reach 86.98%; with salt culture medium to make the seed solution. The analysis of range showed that the optimum condition is as follows: the initial pesticide concentration of 250 mg/L, the temperature of 27 ℃, the initial p H of 7.0, the volume of medium of 200 m L; The result of analysis of Variance show that only more than initial pesticide concentration is not significant factors, Between the subject effect is that emperature > volume of medium >p H, and the optimum condition is: the temperature of 27 ℃, the initial p H of 7.0, the volume of medium of 200 m L. Measured cultivation of 24 h degradation rate could reach 68.81%, cultivation of 132 h degradation rate could reach 92.39%. The isomer selectivity results of degradation of Cypermethrin in mixed bacteria showed that the beta-cypermethrin four isomers without degradation of selective.In order to obtain the microorganism resources which can be used to repair the polluted soil by the beta-cypermethrin and suitable for Xinjiang region soil types and climate conditions, This study obtained microbial resources, The purpose of this experiment was to as a basis for the purpose of soil environmental repair, recovery and develop the biological resources of this area.