Isolation And Characterization Of Fenitrothion-degrading Strain FDS-1(Burkholderia Sp.), Cloning And Expression Of Mpd Gene

A bacterium strain was isolated from fenitrothion-contaminated soil, which was capable of utilizing fenitrothion as the sole carbon source for its growth. This bacterium was identified preliminarily as Burkholderia sp. based on its physiological and biochemical analyses and 16S rDNA series same source analysis and designated as FDS-1(GenBank Accession No. AY550913).Biological properties of strain FDS-1 were analyzed. The optimal pH value for the growth of strain FDS-1 was 6.0-7.0, the optimal temperature was 30℃. The optimal osmotic pressure for the strain FDS-1 was 5-1 Og NaCl/L. The optimal medium for the growth of strain FDS-1 was glucose as carbon source and organic nitrogen as nitrogen source.The optimal pH for degrading fenitrothion by the strain FDS-1 was pH7.0, the optimal temperature was 30℃. The speed of degrading fenitrotion was related positively to initial inoculum size. The strain could degrade fenitrothion rapidly (initial concentration: 10-500mg/L). Fenitrothion (100mg/L) was completedly hydrolyzed to 3-methyl-4-nitrophenol (MNP) by FDS-1 within 1h and MNP was transformed into methylhydroquinone (MHQ) from 1 to 10b. by the method of HPLC analysis. The nitrite was detected in the degrading process. The partial metabolic pathway was deduced from the above results: fenitrothion→MNP→MHQ.A simple and reliable method to assay the activity of organophosphorus hydrolase activity (crude enzyme) was founded. The environmental influences on the activity of organophosphorus hydrolase and the enzymatic kinetic parameters were analyzed. The optimal pH value for enzymatic hydrolysis of fenitrothion was 7.5, the optimal temperature was 30℃. This crude enzyme could keep stability from 20℃ to 40℃ and pH from 7.0 to 8.0. The crude enzyme could keep more stable in the presence of ethanol than other organic solvent. The metal ions could inhibit the crude enzyme activity and the inhibition rate was...