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Nicosulfuron (Nicosulfuron) is a new class of efficient sulfonylurea herbicides, due to the high biological activity and safety of corn, therefore, widely used in corn fields in annual grass weeds, broadleaf weeds and Sara growing woody weeds in. However, long-term heavy use of nicosulfuron residues in farmland ecosystem, resulting in corn cheap to stay exceeded after the stubble-sensitive crops produce injury, could easily lead to the corn weed resistance and the emergence of resistance. With the loss of rain or irrigation water and infiltration Nicosulfuron residual contamination of surface water and groundwater. This study to several strains could effectively degrade Nicosulfuron photosynthetic bacteria isolated from the maize soil, the Select - strains degradation efficiency highest strain was identified and its Nicosulfuron degradation characteristics for the use of photosynthetic bacteria The bioremediation nicosulfuron residues applications to provide a theoretical basis. The main results and conclusions are as follows: 1. Collect long-term use of Maize Soil Nicosulfuron sample of more than 10, by enrichment culture, the high concentration of nicosulfuron domesticated, the final isolation and purification of six strains (named J5-2 , J5-3, JX-2, JX-3, JX-6, J4-8). Of 16S rDNA (GeneBank accession number HM053962 HM163161, HM163162 HM163160 HM053960 HM053961) and pufM gene (see Appendix) sequence homology analysis indicated that the separation of the six strains are purple non-sulfur bacteria, photosynthetic bacteria an important group. Six photosynthetic bacteria strains in the inoculum size of 2%, 25 ° C, pH 7.5, 2500 Lx lighting conditions cultured for 7 days, HPLC method for the determination of the degradation of the efficiency of the strain of nicosulfuron. The results show that the six strains 400mg.L-1 Nicosulfuron degradation efficiency were 30.8%, 21.4%, 19.8%, 25.6%, 23.7%, 20.1%, which strain J5-2 under the same conditions with the highest degradation efficiency, select the strains for further testing. Morphology, physiological and biochemical characteristics detected, the light absorption characteristics of living cells, 16S rDNA sequence comparison and systems phylogenetic analysis, the preliminary identification of strain J5-2 Rhodobacter sphaeroides (Rhodopseudomonas). Biological characteristics of the study results show that: the strain J5-2 can take advantage of a variety of carbon and nitrogen sources, and nicosulfuron as the only nitrogen source. The optimal growth conditions were as follows: pH 7.0, 30 ° C, 6% of inoculum size, 2500 lx light. Set different Nicosulfuron initial concentration, the degradation characteristics of the conditions on the growth temperature, initial pH value, light intensity, inoculum size J5-2. Studies have shown that, J5-2 1600 mg.L-1 Nicosulfuron tolerated and effective degradation of the adjacent ethyl the lung, Bensulfuron, fenpropathrin other herbicides and pesticides. Nicosulfuron prone to natural degradation under acidic conditions, more stable in neutral and alkaline conditions. J5-2 degradation Nicosulfuron optimal conditions of pH 7.0, 30 ° C, 2500 Lx illumination; Nicosulfuron amount of degradation was not obvious within a certain range, inoculum size; cultured for 7 days in optimal conditions, J5- two pairs of 400 mg.L-1 Nicosulfuron degradation rate of 33.5%.
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