Study Of Efficient Chlorpyrifos-degrading Strain By Ultraviolet Mutagenesis

This study showed chlorpyrifos high efficient degrading bacteria separated and screened from the sludge of aeration tank in the wastewater treatment plant was mutated by ultraviolet rays.This result determined the mutagenic bacteria DXl with the best Chlorpyrifos degradation rate in the condition of120s exposure time by20W ultraviolet rays from30cm away. Compared with the original high efficient degrading bacteria,the degradation rate of mutant strain DXl increased by11.26%with the gas chromatographic detection.The study investigated the growth curve and degradation characteristic of the mutagenic strain DX1in different temperature,PH, chlorpyrifos concentration, bacterial inoculation quantity and nutrients, respectively.The result showed the best growing and Chlorpyrifos degrading time of strainDXl was3d and48h.The best culture temperature was30℃with Chlorpyrifos degradation rate78.88.The suitable PH value of the strain growth was7,but the best PH of degradating rate was6.The appropriate chlorpyrifos concentration of promoting strain growth and Chlorpyrifos degradation rate is separately500mg/L and100nig/L.The feasible content of glucose of developing the strain DX1and strengthening chlorpyrifos degradation was1.00%and0.30%.1.00%and0.20%of NH4NO3content was appropriate to the growth of the strain DX1and Chlorpyrifos degradation.The mutant strain DX1was confirmed as Bacillus cereus by the identify of morphology character, physiological and biochemical property and molecular biology,which was the third kind Biological Safety Level by Microbial safety classification standard in my country,and was no harm to human,animal and environment in the normal conditions.The chlorpyrifos degrading rate of the strain DX1in the soil environment was studied by the orthogonal test designed four factors contained PH,fertilizing amount,humidity, bacterial inoculation and three levels in pot experiment of spinage.The result concluded the best chlorpyrifos degradation conditions in the soil, which PH was7, the organic manure content was5mg/kg,the humidity was70%and the inoculation was50ml/kg.PH value of soil and bacteria inoculation had a significant degree of influence for degradating Chlorpyrifos. In the meantime,the residual quantity of Chlorpyrifos was determined in the spinach leaves,and it showed that the higher the Chlorpyrifos content in the soil,the greater the absorption in the spinach.