Isolation And Identification Of Carbofuran-Degrading Microoganism And Its Degrading Characteristics

A method was established to isolate and screen microorganism which could degrade carbofuran. One carbofuran-degrading strain named CDS-1 was isolated from activity sludge. CDS-1 was primarily identified as Sphingomonas sp. according to its physiological & biochemical characters and the homology analysis of its 16S rDNA sequence.CDS-1 could completely degrade carbofuran in the medium within 14hrs with the initial concentration being 100mg/L. The degrading rate was highest among the reported carbofuran-degrading strains.CDS-1 could use glucose and maltose as its optimal carbon source. Most of the common nitrogen source could be used by CDS-1 except NaNO2 & carbamide, but organic nitrogen source was better than inorganic nitrogen source in supporting the growth of CDS-1. The growth of CDS-1 could be inhibited by high NaCl concentration (10g/L~15g/L.), the inhibition effect was aggravated with the increasing of NaCl in the medium. CDS-1 was sensitive to temperature and not able to grow above 37C.The carbofuran-degrading experiment of CDS-1 was carried out in lab scale, the results showed that the highest degrading efficiency was obtained with pH, temperature being 7.0, 30C respectively; the change of aeration had no influece on degrading rate; the increasing inocula could accelerate carbofuran degrading progress; the degrading capability of CDS-1 wasn't inhibited by high carbofuran concentration; the addition of low concentration of nutrients had no distinct effect on the degrading rate while high concentration had inhibiting effect The distribution of degrading enzyme was also primarily studied, the results showed that degrading-related enzyme was endocellular and degrading progress was not cometabolism.GS-MS method was employed to analyze the degrading pathway of carbofuran. The result showed that the initial degrading product was carbofuran-7-phenol,then 2,4-bis-tertiarybutylalcohol-phenol which had never been reported before. Another red substance 2 4-bis-tertiary butyl-quinone was also found in the mixture, as for its position in the pathway wasn't to be determined yet.In H.R test, withered spots were not found on the surface of tobacoo(NC89) leaves inoculated with CDS-1,which meant that CDS-1 had no pathogenic effect on the plant.