Screening Of The Degrading Strain Of Nicotinsulfuron And Its Degradation Characteristics

Sulfonylurea herbicides are a kind of pesticide herbicides widely used in China in recent years.Due to its low toxicity,high efficiency and broad spectrum,it is favored by the majority of farmers.Among them,nicot-sulfuron with the most s Table structure is the most popular.Nicosulfuron-methyl can be used in combination with other herbicides to eliminate almost all weeds.However,in recent years,nicotinsulfuron has been widely used,and some farmers have used pesticides excessively in pursuit of high yield,resulting in increasingly serious pesticide pollution.Therefore,the screening of environmental remediation microorganisms and the application of genetic engineering technology have become urgent.Soil samples were collected in Baiquan County,Qiqihar City,Heilongjiang Province.Through domestication and enrichment,a strain with high degradation rate of nicotsulfuron was selected.Under the concentration of 100 mg/L nicotsulfuron,the degradation rate reached86.7% within 48 hours.16 S r RNA identification revealed that the strain was Burkholderia sp.,named DG-10.Burkholder strain is mainly used as a plant antimicrobial agent,which can produce indole acetic acid to promote plant growth.In this study,the growth curve of the degrading strain Burkholder DG-10 was measured at first.The growth rate was accelerated at 4-8 h,increased exponentially at 10-16 h,decreased after 16 h,decreased obviously after 20-26 h,and leveled off after 28 h.The results showed that the optimum p H was 6.0,the optimum temperature was25 ?,and the optimum substrate concentration was 100 mg/L.Degradation rate of glucose increased with the addition of carbon source,but the increase of potassium nitrate,urea,ammonium nitrate and ammonium chloride was not obvious.In the localization of degradation products,degradation pathways and degradation enzymes,it was found that the degrading strain Burkhold DG-10 could degrade nicotsulfuron into 7products by liquid mass spectrometry and high performance liquid chromatography,which were respectively: 2-((4,6--dimethoxypyrimidine-2-yl)amino)-N,N-dimethylamide,2-(1-(4,6--dimethoxypyrimidine-2-yl)amino)-N,N-dimethylamide,2-(1-(4,4)The degradation pathway of6-dimethoxypyrimidine-2-)-ureyl)-N,N-dimethyl-nicotinamide),2-amino-4.6-dimethoxypyrimidi ne,M1,N,N-dimethyl-2-aminosulfonyl-3-pyridinamide,(4,6-dimethoxy-ethyl-pyrimidine)urea,2-amino-4.6-dimethoxypyrimidine was preliminarily determined.Through the localization experiment of degrading enzyme,we finally determined that degrading enzyme was located outside the cell and belonged to the exocrine protein.At the same time,the experiment also carried out the microbial remediation effect of degrading and degrading strain DG-10 in indoor simulated environment.Under the condition of 100mg/L for28 days,the degradation rate of nicotinsulfuron was 83.30%In this experiment,a new strain,Burkholderia,which can degrade nicotinsulfuron was screened mainly through the above experiments.The physiological and biochemical indexes,degradation characteristics,degradation products,degradation pathway and degradation enzyme localization of the strain were determined,which enriched the species of the degrading strain of nicotinsulfuron,and provided new resources for environmental microbial remediation and a new research direction for the study of Burkholder strain.