Degradation of methamidophos by Hyphomicrobium species MAP-1 and the biochemical degradation pathway

Biodegradation. 2010 Jul;21(4):513-23. doi: 10.1007/s10532-009-9320-9. Epub 2009 Dec 4.


Methamidophos is one of the most widely used organophosphorus insecticides usually detectable in the environment. A facultative methylotroph, Hyphomicrobium sp. MAP-1, capable of high efficiently degrading methamidophos, was isolated from methamidophos-contaminated soil in China. It was found that the addition of methanol significantly promoted the growth of strain MAP-1 and enhanced its degradation of methamidophos. Further, this strain could utilize methamidophos as its sole carbon, nitrogen and phosphorus source for growth and could completely degrade 3,000 mg l(-1) methamidophos in 84 h under optimal conditions (pH 7.0, 30 degrees C). The enzyme responsible for methamidophos degradation was mainly located on the cell inner membrane (90.4%). During methamidophos degradation, three metabolites were detected and identified based on tandem mass spectrometry (MS/MS) and gas chromatography-mass spectrometry (GC-MS) analysis. Using this information, a biochemical degradation pathway of methamidophos by Hyphomicrobium sp. MAP-1 was proposed for the first time. Methamidophos is first cleaved at the P-N bond to form O,S-dimethyl hydrogen thiophosphate and NH(3). Subsequently, O,S-dimethyl hydrogen thiophosphate is hydrolyzed at the P-O bond to release -OCH(3) and form S-methyl dihydrogen thiophosphate. O,S-dimethyl hydrogen thiophosphate can also be hydrolyzed at the P-S bond to release -SCH(3) and form methyl dihydrogen phosphate. Finally, S-methyl dihydrogen thiophosphate and methyl dihydrogen phosphate are likely transformed into phosphoric acid.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Proteins / metabolism
  • Biodegradation, Environmental
  • DNA, Bacterial / genetics
  • DNA, Ribosomal / genetics
  • Hyphomicrobium / classification
  • Hyphomicrobium / enzymology
  • Hyphomicrobium / isolation & purification
  • Hyphomicrobium / metabolism*
  • Insecticides / chemistry
  • Insecticides / metabolism*
  • Molecular Sequence Data
  • Molecular Structure
  • Organothiophosphorus Compounds / chemistry
  • Organothiophosphorus Compounds / metabolism*
  • Phylogeny
  • RNA, Ribosomal, 16S / genetics
  • Soil Microbiology*


  • Bacterial Proteins
  • DNA, Bacterial
  • DNA, Ribosomal
  • Insecticides
  • Organothiophosphorus Compounds
  • RNA, Ribosomal, 16S
  • methamidophos