The Isolation Of Cypermethrin Degrading Fungi And The Research Of Its Degradation Characteristics

In this dissertation,taking cypermethrin as a model pollutant,its HPLC analytical method,degrading-fungi enrichment and isolation,biodegradation characteristics of the fungi, the extract of cypermethrin degrading enzyme and its biodegradation characteristics were studied systematically. The results could be summarized as follows:1.The HPLC analytical method of cypermethrin residues in environment was set up. The cypermethrin residues in water were extracted with an equal volume of petroleum ether and then analyzed by high performance liquid chromatography. Cypermethrin was detected by HP-1100 high performance liquid chromatography.The operating conditions were described below:C18 chromatographic column,the temperature of column was 35℃, the detector was diode-array detector(DAD),detecting wavelength was 235nm,the mobile phase was acetonitrile-water(V:V=80:20),flow velocity was 1 mL·min^-1, sample size was 10μL.Under these conditions, the retention times for cypermethrin were 3.641 min and 3.881 min.The recovery rates from fluid medium with concentration of 1,10,50,100 mg·L^-1 were between 86.68%¹02.25% and the coefficient of variation of determination results were between 1.32%².85%. 2.The cypermethrin degrading-fungi were isolated by enrichment culture from sludge at sewage outlet of the pesticide factory.Three efficiently degrading strains,with cypermethrin as sole carbon source,were isolated and named TS-203, TS-205 and TS-306.The threee efficiently degrading strains TS-203,TS-205,TS-306 were identified as Fusarium, Monilochaetes and Aspergillus terreus.The degradation rates in 5 days to cypermethrin with concentration 100 mg·L^-1 of the three fungi were 94.5%,91.4% and 84.5% respectively.3.The effects of different concentrations of carbon sources,pH,culture temperature and cypermethrin concentration on fungal growth and biodegradation ability were determined.The results showed that the fungal growth and biodegradation rates were higher when cypermethrin was the sole carbon source with concentration of 50～150 mg·L^-1,pH 6.0～8.0 and temperature 30～40℃. 4.Studied the degrading enzyme, which was extracted from the efficiently degrading strain TS-203.The degrading activity of ectoenzyme and endoenzyme were measured. The results showed that the cypermethrin degradation rate of endoenzyme was 59.8% and ectoenzyme which was extracted with (NH4)2SO4 was 10.3%. So the degrading enzyme was endoenzyme mainly. The solubility protein of the endoenzyme was 1240μg·mL^-1 which was determined with Albumin(bovine serum) as standard protein.The optimum pH for enzymatic degradation of cypermethrin was 7.0 and the optimum temperature for enzymatic activity was at 30℃.The Km and Vmax of the enzyme was 6.8120×10-4 mmol·mL^-1 and 1.1799×10-4 mmol·min^-1,respectively. Additional experimental evidence suggests that the endoenzym of fungus TS-203 had good stability and endurance for temperature and pH which could efectively degrade cypermethrin.