Degradation of methamidophos by Hyphomicrobium species MAP-1 and the biochemical degradation pathway.
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.
Wang
Li
L
Department of Microbiology, Key Laboratory for Microbiological Engineering of Agricultural Environment of Ministry of Agriculture, Nanjing Agricultural University, 210095, Nanjing, People's Republic of China.
Wen
Yang
Y
Guo
Xinqing
X
Wang
Guangli
G
Li
Shunpeng
S
Jiang
Jiandong
J
D001426:Bacterial Proteins / Q000378:metabolism; D001673:Biodegradation, Environmental; D004269:DNA, Bacterial / Q000235:genetics; D004275:DNA, Ribosomal / Q000235:genetics; D020582:Hyphomicrobium / Q000145:classification / Q000201:enzymology / Q000302:isolation & purification / Q000378:metabolism*; D007306:Insecticides / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D015394:Molecular Structure; D009946:Organothiophosphorus Compounds / Q000737:chemistry / Q000378:metabolism*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012988:Soil Microbiology
D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D007306:Insecticides; D009946:Organothiophosphorus Compounds; D012336:RNA, Ribosomal, 16S; C014655:methamidophos