Study On Screening,Identification And Degradation Efficiency Of Highly Efficient Degrading Microbe For Imazethapyr

With the widespread use of chemical pesticides,especially herbicides,such problems as soil pollution,water pollution and crop growth inhibition are following.Although imazethapyr has the advantages of high efficiency and broad spectrum,the herbicide has a long half-life and is not easy to break down.The long-term use can cause crop injury and a lot of trouble about crop rotation.Therefore,how to solve the problem remains a critical task.In this paper,we screened out the microbial strains that can degrade imazethapyr,and laid the foundation for the study of the rapid and effective biodegradation of imazethapyr.The main results are as follows:1.The soil samples collected from Pingshan pharmaceutical outfall,soybean around Harbin.Northeast Forestry University forestry demonstration center and Daxinganling forest region and other places for separation,screening,purification,104 different soil fungi and bacteria were obtained,High performance liquid chromatography(HPLC)was used to determine the degradation efficiency of each strain,then pf3,F1(2 strains of fungi),and Cl(1 strains of bacteria)were screened out.According to the source of highly effective degrading microbe,the degrading rate of the microbe from the soil by the long-term stimulation of pesticide is higher;microorganism also has certain degradation ability from forest soil uncontaminated with pesticides.2.Through ITS rDNA and 16SrDNA sequence analysis,combined with the morphological characteristics,identification shows that:degrading fungi pf3 is Trichoder?ma brevicompactum,F1 is Trichoderma harzianum and Cl is Serratia marcescens.3.By imazethapyr concentration gradient experiments,medium pH gradient experiment,temperature gradient experiments,the most suitable conditions for the degradation effect of the degradation fungi pfG(T.brevicompactum)are:degradation of imazethapyr concentration of nicotinic acid salt medium is 100 mg/kg,pH=8,the optimum degradation temperature range is 25-35 ?.4.Through the contrast experiment of the degradation ability of CI and pf3,it can be concluded that the degradation effect of p3 was better in soil environment,and Trichoderma is beneficial to plant growthh,so it has wide application prospect.5.Through the soil pot experiment with different concentration of Imazethapyr,liquid chromatography was used to detect the imazethapyr content in experimental soil,finally obtains that the concentration of Imazethapyr in soil was 100 mg/kg when the microbe could play a great role in degradation.High concentration of Imazethapyr can inhibit the degradation of degrading microbe,and it may not be detected or produce a large error when the concentration is too low.6.By using high-throughput sequencing methods,comparing the soil microbial diversity before and after the experiment,indicated that Soybean growth and degrading fungud pf3 had a significant impact on soil microbial diversity,pf3 had a enormous proliferative capacity,and can be effectively planted in the soil.By using Kjeldahl method,diffusion method,molybdenum antimony colorimetric method and flame photometric method,the contents of total nitrogen,available nitrogen,available phosphorus and available potassium were measured before and after the experiment.It was found that Soybean growth and degrading fungus pf3 had an effect on the content of N,P and K in soil.This study provided a basis for the feasibility of high efficiency degradation of Imazethapyr,and laid a theoretical foundation for the research on bioremediation of contaminated soil and the development of biological agents.