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.
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.
甲胺磷是一种广泛使用的有机磷杀虫剂，通常可在环境中检测到。从中国甲胺磷污染土壤中分离到一株能够高效降解甲胺磷的兼性甲基营养型细菌 Hyphomicrobium sp. MAP-1。结果表明，甲醇的添加显著促进了菌株 MAP-1 的生长，并增强了其对甲胺磷的降解能力。此外，该菌株可以利用甲胺磷作为其唯一的碳、氮和磷源进行生长，并可以在最佳条件（pH 7.0，30°C）下在 84 小时内完全降解 3000mg/L 的甲胺磷。负责甲胺磷降解的酶主要位于细胞内膜上（90.4%）。在甲胺磷降解过程中，根据串联质谱（MS/MS）和气相色谱-质谱（GC-MS）分析，检测并鉴定了 3 种代谢产物。利用这些信息，首次提出了 Hyphomicrobium sp. MAP-1 对甲胺磷的生化降解途径。甲胺磷首先在 P-N 键处断裂，形成 O,S-二甲基硫代磷酸和 NH3。随后，O,S-二甲基硫代磷酸在 P-O 键处水解，释放-OCH3并形成 S-甲基二氢硫代磷酸。O,S-二甲基硫代磷酸也可以在 P-S 键处水解，释放-SCH3并形成甲基二氢磷酸。最后，S-甲基二氢硫代磷酸和甲基二氢磷酸可能转化为磷酸。
