Isolation, Characteristics And Degradation Of A Methyl Parathion-degradation Bacterium

The role of organophosphorus pesticides is irreplaceable in the control of plant-pest disease. Human and animal health and environmental pollution directly or indirectly are harmed by organophosphorus pesticides which have been extensively and vastly used in agricultural production. Although the government forbidden the utilization of monocrotophos, methamidophos, methyl parathion, methyl parathion and ammonium phosphate in January 1 st 2007, the five kinds of organophosphorus pesticides, from the aspects of use and high efficiency, will continuously be used in agricultural production for a long time. Therefore , the study of degrading methyl parathion is of great importance.In this thesis, the strains wered screened form soil polluted by pesticides. One bacterium named JM-013 was obtained with high performance of methyl parathion degrading ability, which was identified as Clostridium butyricum initially by observation of its modality and physiological and biochemical test.After the UV scanning analysis of the degradation products, the strain named Clostridium butyricum degraded the methyl parathion to P-nitrophenol by its degrading enzyme; The bacterium can maintain genetic stability and broad-spectrum after multi-generation reproduction; When the medium with methyl parathion was added to glutamic acid, a-ketoglutaric acid, aspartic acid, malic acid, citric acid sodium, the ability of the strain named JM-013 degrading methyl parathion can be improved greatly; according to the experiment of co-metabolism, It is initially speculated that the degradation of methyl parathion is closely related to TCA cycle.The signal factor of the degrading methyl parathion showed that the best culture conditions of the JM-013 was as follows: 1.3% sodium citrate, 0.08% ammonium nitrate,pH 7.5, 35℃, 200r/min, inoculum 6%; The carbon, nitrogen, temperature and inoculum are the main effect factors. The best methyl parathion degrading condition was ascertained by orthogonal experiment as follows: the best experiment combination was A₂B₃C₃D₁, that is 1.3% sodium citrate, 7% inoculum, 0.01% ammonium nitrate and 33℃. According to the combination single-factor experiments orthogonal test to optimize the fermentation conditions, the degrading rate of methyl parathion was able to reach 62.56%...