Methamidophos (O,S-dimethyl phosphoramidothioate) is a widely used organophosphorus insecticide. Because of its persistence and toxicity, its use has been prohibited or restricted in several countries. Thus its biodegradation is of interest (Wang et al., 2010).
Hyphomicrobium sp. MAP-1 can utilize methamidophos as its sole carbon, nitrogen, and phosphorous source for growth. The first step in the pathway is cleavage of the P-N bond to form O,S-dimethyl hydrogen thiophosphate. This is hydrolyzed at either the P-O bond to form S-methyl dihydrogen thiophosphate, or the P-S bond to form methyl dihydrogen phosphate. It is proposed that these last two compounds are further hydrolyzed to phosphate (Wang et al., 2010).
The following is a text-format methamidophos degradation pathway map. Organisms which can initiate the pathway are given, but other organisms may also carry out later steps. Follow the links for more information on compounds or reactions. This map is also available in graphic (5k) format.
Methamidophos
Hyphomicrobium sp.
MAP-1
|
|
| methamidophos
| phosphoamide hydrolase
|
v
O,S-Dimethyl hydrogen
phosphorothioate
|
|
|
+---------------+----------------+
| |
| O,S-dimethyl hydrogen | O,S-dimethyl hydrogen
| phosphorothioate | phosphorothioate
| phosphodiesterase | esterase
| |
v v
S-Methyl dihydrogen Methylphosphate
phosphorothioate |
| |
| |
| S-methyl dihydrogen | methylphosphate
| phosphorothioate | phosphomonoesterase
| esterase |
| |
+---------------+----------------+
|
|
|
v
Phosphate
Page Author(s): Sujana Mittapalli
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