Selection And Identification Of Strains To Degrading Herbicide Chlorimuron-ethyl And Stuides On Degradation Characteristics Of Strains

As a new kind of sulfonylurea herbicide,chlorimuron-ethyl has attraeted many researchers' attention.But,The knowledge about chlorimuron-ethyl residue on the soil micro-ecological impact and the sensitive crop stubble after the injury was still superfieial.The results of this research can be summarized as follows:(1) The first part present several strains capable of degrading were isolated and screening. Through enrichment culture and separation 49 strains were isolated from soil of long term applied with chlorimuron-ethyl.Then,three bacteria(X₁,X₂,X₃) and a fungi(Z₁) with high degradating activlty(degradation rate＞80%) were chosen and diseussed.(2) Based on the morphological appearances,physiological and biochemical characteristics, three bacteria(X₁,X₂,X₃) were identified as strong bacteria Bacillus(B.firmus,B.laterosporus and B.brevis).Together with 18 S rDNA sequence,a fungi(Z₁) was identified as Trichoderma longibrachiatum.(3) In the second part,the culture conditions of the four strains were optimized respectively. The optimum temperature and volume of medium for facilitating the growth of the four strain were 30℃and 50 mL/250 mL.The appropriate pH for X₁.X₂ and X₃ were 7.0.(4) In pure culture,the three bacteria and one fungi could degrade chlorimuron-ethyl very efflcienctly at the concenteration of chlorimuron-ethyl 10 mg/L in maiyazhi medium under the condition of the volume of medium was 50 mL/250 mL.Result shows that a good degradation effect of X₁ and X₂ was found at the condition of 30℃and pH 7.5.And the favorable environment of X₃ was temperature 25℃,pH 7.5.Where as,the optimum temperature and pH for Z₁ to egradate chlorimuron-ethylthe was 25 and 7.0 respectively.(5) Three bacteria(X₁,X₂,X₃) were cocultured to degrade chlorimuron-ethyl very efficienctly,The degradation effect of parallel every unitary bacterial strain and some bacterial strains:Fungus Z₁ and bacterium X₃ koinonia degradation rates maximal,but reach 91.65%;And the koinonia degradation leads bacterium X₁,X₂ and X₃ to be 84.88%.