| The sulfonylurea serbicides, widely used for more than 20 years, have been exploited and used to enhance the development of pesticide and the agriculture production. However, widespread use of pesticide will result in immense potential jeopardize to the environment. The bioremediation technology which utilizes microorganism to degrade the pesticide is fast, safe and low cost.A strain, Brevibacterium sp. BH, with good capability to degrade bensulfiiron-methyl, was isolated from soil, could high efficiently degraded bensulfiiron-methyl. BH was used to bioremediate bensulfiiron-methyl simulated-contaminating soil. Biological community assessments including cuturable bacteria and soil enzyme activities were carried out in laboratory condition to investigate the effects of bensulfuron-mthyl and its degrading srain at different concentrations on soil micro ecosystem. These results will be useful reference to the fast degradation of the herbicide and the bioremediation of the polluted paddy soil. The main contributions are listed as follows:When BH was added to the simulated-contaminating soil, it had a strong ablility to degrade the bensulfiiron-methyl remarkably. Degradation of bensulfiiron-methyl in the paddy soil in the control group is very slow. After 14d from using the herbicide, the remnant of the pesticide still holds a percentage of more than 80%. However, as it comes to the soil adding BH, the remnant is decreased to about 12%. BH had obvious degradation efficiency under different concentration ranges from 0.08-0.4mg·kg-1. In the soil added the BH bacteria, the bensulfuron-methyl could be rapidly degrade by 80% in two weeks, along with the consume of the nutriment in the soil, the degradation speed will be slowed down after 14d.The activities of four types of enzymes, including urease, invertase, proteas and catalase were measured in this study to evaluate the effect of bensulfuron-methyl its degrader BH to paddy soil. Different results of enzyme-activities were acquired from soil samples treated with bensulfuronmthyl and BH. The urease activities were simulated at 4d and 21d after bensulfuron-methyl treatment. Bensuifuron-methyl inhibited the activities of invertase and catalase, especially for the latter. When adding BH to polluted paddy soil, the activities of above three was similar to the control group. The protease was firstly simulated then inhibited in the soil containing the bensulfuron-methyl, while in the soil adding bensulfuron-methyl and BH, it was inhibited all the time. The influences of bensulfuron-methyl and its degrader strain BH on the cultural microorganisms in paddy soil showed that the aerobe differed markedly in their response to bensulfuron-methyl and BH. When added at a concentration of 4μg·g-1 dried soil, the bensulfuron-methyl would have influences to the various microorganism in the soil, and the using of BH would slow down such a process to some degree. The numbers of bacterial were increased in soil samples treated by bensulfuron-methyl, while the strain BH performed the restrain function after pesticide was degraded. Results showed that different from the fact that actinomycetes could be stimulated by bensulfuron-methyl; fungi were reduced to a lower level after treatment.The aerobe in soil samples responded differently after treatments. According to the data from the experiment, the azotobaeter was activated to a high point at first stage of treatment, while cellulolytic bacteria was reduced mostly during the the whole experimental period. Ammonifying bacteria could increase to a high level in soil after bensulfuronmethyl treatment. After the bensulfuron-methyl being degraded by BH, such influences would be removed.
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