The Research Of Pesticide Degradation Bacterium Screening By Using High Concentration Of Salt

In recent years, research of degradation pesticide, processing pesticide-contaminated by using microbial was attended increasingly. Selected high efficiency degradation bacterium, is the foundation and focus of this research, and rationality of the method is the key of high efficiency degradation bacterium selection.Based on the disadvantage exist in traditional pesticide degradation bacterium screening methods, this article proved the innovation and improvement for the method. This research test if it is possible by using high salt as extreme condition to found farm chemical degradation bacteria. Four chemical: Beta-cypermethrin, Chlorpyrifos,clomazone,3,4-DCA,were used as contaminant in this experiment. So these series of researches have provided references to the further works on environal-microbe applying on farm chemical, the main results are as follows:1 The selection of salt-tolerant bacteriaA total of 22 bacteria isolates from the enrichment survived and grew on the CHS(10%NaCl)medium agar plate considered to be the moderately slat-tolerant bacteria (MSTB).All the colonies can be observed clearly in 4ds incubate time on CHS medium agar plate. In the experiment of isolating extremely salt-tolerant bacteria (ESTB),only 6 moderately slat-tolerant bacteria (MSTB) survived and grew on the EHS (15%NaCl) medium.2 Tolerant of farm chemicalAs the result shown, the growth of 6 ESTB strains are different by using normal LB medium.But the optical density value of all strains rise to more than 0.7 after 12h and 1.0 after 24h incubation. Although there is passive affection of growth in initial 24h by using 4 chemical adding medium. But the optical density also can rise to about 2.0 in 48h like grown in normal LB medium. Growth of almost another 16 strains are like the same.So we can observe difference of 22 strains growth and the affection of using normal LB medium and 4 chemical adding medium, but it is consider too slight to impacting the degradation.3 Degradation of 4 agricultural chemicals by STBsThe following can be concluded from above analysis on the bio-degradation efficiency (BE) after two days of culture of the isolated bacteria.1) The ESTBs had greater BE than the MSTBs, which is true identically for four agricultural chemicals. The improved BE between the ESTBs and NSTBs was the most for 3,4- dichloroaniline (49.9%), and the least for clomazone (14.2%) among the four chemicals.2) The bio-degradation efficiency was the highest for 3,4-dichloroaniline, and the least for clomazone.3) The most effective bacteria varied among the chemicals, e5 for clomazone (BE 32.0%) and beta-cypermethrin (BE 85.8%), e6 for 3,4- dichloroaniline (BE 94.9%) and e3 for chlorpyrifos (BE 79.3%).4 The identify and degradation research of ESTBsThrough the six in ESTBs 50mg/l concentration chemical solution growth and degradation curve, found its (DE) may be affected by growth time and drug residues:1) the most efficiency degradation was observed in grown period of logarithm, and on the contrary the lowest DE was shown in decay stage 2)the positive correlation was found between the DE and chemical residues The rate of degradation is vary fit first-order kinetics. Through the 16srRNA detection 6 ESTBs appraisal result is as follows:e1 is identified as Bacillus cereus strain TAUC5 (similarity>99.9%).e2,e4 is identified as Bacillus licheniformis (similarity≈97.8%).e3 is identified as Bacillus pumilus sp. GN-6(similarity≈99.1%). e5 is identified as Uncultured Bacillus sp. partial (similarity≈97.9%).e6 is identified as Streptomyces sp.702(2011) (similarity≈98.6%)...