| Pesticides play an important role in the control of plant diseases and insect pests. But they also destroy the environment seriously and leave great toxicity to human heath. Biodegradation, especial the degradation by microorganism, can ease this kind disadvantage.In this research, several strains with potential ability of degradation for organophosphorus pesticides were isolated from the activated sludge polluted by organophosphorus pesticides sampled from one pesticide factory in harbin city. Amongthem, HDMJ-2 and HDMJ-23 were screened and selected as the high efficiency degradating isolates. They were identified as Pseudomonas sp.HDMJ-2 and Aerococcus sp.HDMJ-23 based on their morphological charachateristics, physiological and biochemical properties and the sequence analysis of their 16srDNA, seprately。The research result showed that two strains did well in biodegradation omethoate and other organophosphate pesticides. The omethoate at the concentration of 100mg/L could be degrade absolutely in 1d with the two strains, while the concentration of 400mg/L could be degrade absolutely in 3d. when the concentration of omethoate were up to 1000mg/L, it could be degraded in 7d. The degradation rate was 75.28% and 72.42%, respectively,, while the omethoate at the concentration of 2000mg/L.The study on the Biological characteristics of the two strains for their growth and degradating organophosphorus pesticide showed that they had broad-spectrum degradability, especially for degradating omethoate. The strains could tolerate high concentration of 8000mg/L omethoate with inorganophosphate medium. The degradating process of isocarbophos took on fluctuating and the trend was related to the growth curve of the strains.In the study on the Biological characteristics of the strains show that the optimum carbon source for the two strains was cane sugar and D- carubinose. the optimum nitrogen source for both strains was beef extract, the two strains could grow well when the temperature changes between 25℃-40℃and pH changes between 5-8. moreover, the result indicated that they could growth well at the concentration of omethoate lower than 1000mg/L.In this dissertation, the method of high-efficiency biodegradation bacterium HDMJ-2 and HDMJ-23's immobilization were studied. Processed by iatrical syringe titration method, and filter four kinds embedding material: sodium alginate, poly vinyl alcohol, carrageenan and chitosan. The results of the experiment indicated that the particle manufactured by 3%~4% sodiumalginate with 4# iatrical syringe pinhead can be satisfied the requirement of the dissertation.The biodegradation of omethoate in soil with strains and immobilized strains was researched by the application of strains and immobilized strains in Anda and botanical garden soil in harbin, the results of the experiment showed that The two strains and immobilized strains could biodegrade the omethoate efficiently. The biodegradation rate of omethoate by the two strains and immobilized strains was higher in botanical garden soil sample than in Anda soil sample. This result maybe caused by a great deal of organic material in botanical garden soil sample which could provide the nutrition for the two strains and could absorbed omethoate .The biodegradation of omethoate in sewerage by the two strains and immobilized strains were studied. The experiment results showed that the biodegradation rate of omethoate approach 100%. This result was not ideal compared with the results in mediums. Absence of nutrition and oxygen was the main reason of this situation. The degradation rate of omethoate by the two strains was higher than by immobilized strains under 150mg/L, but it was almost the same as under 500mg/L.The experiment results indicated that the ability of tolerance of adversity of the immobilized strains maybe enhanced, .as the time slips by, the osmosis of immobilized strains upgrades. |
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