Identification Of Nicosulfuron-degrading Bacterium CJ-1 And Its Characteristics

Nicosulfuron is a kind of sulfonylurea herbicide.Because of its high efficiency,low toxicity and low residue,nicosulfuron is widely used at home and abroad.But with the increase of application amount and improper use method,it causes a large number of residues in the natural environment,which brings great harm to human beings,animals and the environment.Microbial degradation is one of the main degradation methods of nicosulfuron herbicide,because of its high efficiency,economy and environmental protection.Therefore,microbial degradation has become a hot issue of domestic and foreign scholars,and it is of great significance to the ecological environment and food security.In this study,a strain CJ-1 with high degradation ability to nicosulfuron was isolated from the soil of maize field where nicosulfuron was applied for a long time in Shangzhi City.The degradation rate of CJ-1 to nicosulfuron was 76%in 48 hours,and the degradation effect was ideal.The morphological characteristics,physiological and biochemical identification results and 16S r DNA sequence results of CJ-1 were compared.The strain CJ-1 was identified as Enterobacter sp.and registered in Gen Bank with the registration number of MT361077.Through the study on the growth and degradation ability of CJ-1,it was found that the growth and degradation effect of CJ-1 were ideal at 48h.It was found that the growth and degradation of CJ-1 were influenced by external factors,the optimum inoculation amount for growth and degradation of the strain was 3-5%,the optimum substrate concentration is 50 mg/L,the optimum p H value is 7 and the optimum temperature is 30?.In the experiment of soil remediation for nicosulfuron pollution,the degradation rate of CJ-1to nicosulfuron was higher than that of contaminated soil.When the soil with nicosulfuron concentration of 10 mg/kg was inoculated with different amount of inoculum,under dark conditions,culture at 30?for 21 days,sample and detect residual substrate concentration.The results showed that the degradation effect was the best when the inoculation quantity was 1×10~8CFU/m L,and the degradation rate was 65%.Adding 1×10~8CFU/m L CJ-1 suspension to the soil with different Nicosulfuron concentration,the highest degradation rate was 71%when the substrate concentration was 1 mg/kg.According to the analysis results,the degradation effect increased with the increase of the amount of bacteria,and decreased with the increase of the substrate concentration.The overall results showed that CJ-1 had relatively good degradation ability to nicosulfuron herbicide,this study provides a theoretical basis for the degradation of nicosulfuron in soil.