Isolation And Characterization Of Pesticide Degrading Bacterium From Chinese Agricultural Soils

Biodegradation is a very important environmental progress of pesiticide catabolism. Microorganism, mammal, aqutile, insects and plants have inreplacebal function of pesticide degradation, while micro-biological degradation is one of the most important factor. Micro-biological degradation is a new pesticide degradation pathway compared to the tradationaly physical and chemical methods. According to its low input, non-toxic, non-residue, non-secondary pollution and great manage results, micro-biological degradation has been recognized as a low cost and environment friendly method to remove pollutants. In this research,114degrading bacteria were separated from different kinds of agricultural soils. Then the bacteria were screened according their degrading ability of imidacloprid, and the influence of pesticide using to microorganisms in different agricultural soils was evaluated according to the analyses of pesticide using history, bacteria quantity and degrading abilities. One efficient degrading bacterium was screened to have biochemistry and gene sequence identification. Also, the optimum growth conditions, degrading spectrum and sensitivity to different kinds of antibiotics of this degrading bacterium was preliminary researched. The main research results were as follows:1.114pesticide degrading bacteria were separated from28kinds of agricultural soils which were collected from Shandong provence and Beijing. Then they were screened by the degrading ability to imidacloprid and evaluated the influence of pesticide using to microorganisms in soil. The pesticide application amount and frequency enormously influenced microorganism distribution in soil, and may change the microorganism degrading ability to pesticides directively.2. Besides the bacteria separated from soils, there were26strains of bacteria have degrading rates of0-10%to imidacloprid,78strains in10-25%, and10strains more than25%. While one efficient degrading strain1-2-4seperated from ginger soil in Weifang had imidacloprid degrading rates of41.60%, and this efficient degrading bacterium was selected for identification and characteristic analysis.3. The bacterium1-2-4was named Acinetobacter sp. strain ZX01by biochemistry and gene sequence identification. The strain was aerobiotic, immobile, non-spore generated gram-negative bacterium. The strain had positive reaction to catalase and negative reaction to oxidase and urease. Additionaly, the strain can utilize glucose, sucrose, melibiose, arabinose and sodium citrate to growth while can not use mannose, inositol, sorbitol, rhamnose and amarogentin.4. The scanning microscope results revealed that the strain ZX01belongs to coccobacillus and diameter between0.7-0.9μm. In addition, the optimum growth condition of degrading bacterium was pH7-8and temperature33℃, so it has good applied capability in normal environmental conditions.5. The growth of degrading bacterium had positive correlation to cyromazine degradation. Cyromazine was gradually degraded in the medium by the quantitatively increase of bacterium. The degrading bacterium growth to stationary phase in60hours, and100g/mL cyromazine was almost totally degraded. Besides, the bacterium ZX01showed immense degrading results to many pesticides and expand degrading spectrum. It had degrading rates of more than70%to8kinds of pesticide and can remove many different kinds of pesticides in the environment.6. The sensitivity to8kinds of antibiotics of the bacterium were investigated. The strain showed different sensitivity to concentration of30g/dis、10g/disk and6g/disk by different kinds of antibiotics. While the bacteria revealed hige sensitivity to tetracycline under3concentration, and can be used to control bacterial infection and drug tolerance in the environment.