Screening Of Bacteria For Degradation Of Organophosphorus Pesticides And Preparation Of Fungicides

Pesticides and chemical fertilizers are widely used in agricultural production to prevent diseases and pests and increase crop yields.However,with the large-scale use of pesticides,the harm of pesticide residues is becoming increasingly prominent.With the advantages of high efficiency,low cost,no pollution and no side effects,microbial fungicides can not only improve crop yield,but also degrade pesticide residues.It has become an indispensable product for the green development of agriculture.The purpose of this paper was to screen dichlorvos degradation bacteria,to determine their degradation performance,to identify dominant degradation bacteria by 16 s r DNA method,and to select Bacillus subtilis,fibrotic fiber microbacteria and Bacillus tropicalis to carry out subsequent antagonistic and growth characteristics tests.Finally,the degradation rate of dichlorvos,an organophosphorus pesticide,was the highest when the ratio of the three strains was 4:2:3,up to 60%.It not only reduces the pesticide residues in the environment,but also provides strain resources for the degradation of dichlorvos,which is of great significance to the restoration of the whole ecosystem.1.In this study,18 strains of bacteria were isolated and isolated from laboratory original bacteria Bacillus subtilis(S-3),natural spoilage food and soil contaminated by organophosphorus pesticides(organophosphorus pesticides)for a long time,and 18 strains of bacteria were isolated from the soil polluted by organophosphorus pesticides.These bacteria were cultured in the inorganic salt medium containing dichlorvos(100~500mg/L)in turn,and the strains which could grow well in the inorganic salt medium were screened out.Then the strain type was determined by microscopic examination and morphological observation,and the degradation performance of dichlorvos to dichlorvos was determined by gas chromatography.The results showed that after 10 h,the degradation of DDVP by strain E-1,S-3,Z-7 and H-9 was 32.88%,31.03%,37.82% and 33.72%,respectively.The results of 16 S r DNA identification showed that E-1,Z-7,H-9 were P.aeruginosa,microbacterium of fibrotic fiber,and Bacillus,Because Pseudomonas aeruginosa is a conditional pathogen,it will pollute the surrounding environment when it is used in practice.Therefore,three other strains of Pseudomonas aeruginosa were selected for follow-up test.2.Through the antagonistic test of Bacillus subtilis,fibrotic microbacteria and Bacillus tropicalis,the results showed that the three strains could not antagonize each other and could be cultured together.According to the antagonistic experiment,the growth characteristics of the three strains were studied.The results showed that the growth of Bacillus subtle was thehighest when the p H was 6,the temperature was 30?,the inoculum was 4%,the carbon source was beef extract.When p H was 6,temperature was 37 ?,inoculum was 2%,carbon source was glucose,the growth of Fibrotic microbacteria was the largest.When p H was 5,temperature was 30 ?,inoculum was 3%,carbon source was beef extract,the growth of Bacillus tropicalis was the largest.The best nitrogen source of the three strains was yeast extract.Finally,by the response surface experiment,the optimal ratio of the three strains is4:2:3,the growth of the composite inoculant is the largest,and the degradation rate of the dichlorvos can reach 60%.