Degradation of methomyl by the combination of Aminobacter sp. MDW-2 and Afipia sp. MDW-3

Methomyl [S-methyl N-(methylcarbamoyloxy) thioacetimidate] is a kind of oxime carbamate insecticide. It is considered to be extremely toxic to non-target organism. Up to date, no pure culture or consortium has been reported to have the ability to degrade methomyl completely. In the present study, a methomyl-degrading enrichment E1 was obtained by using the sludge from the wastewater-treating system of a pesticide manufacturer as the original inoculant. Two bacterial strains named MDW-2 and MDW-3 were isolated from this enrichment, and they were preliminarily identified as Aminobacter sp. and Afipia sp., respectively. Strains MDW-2 and MDW-3 could co-exist and degrade 50 mg l−1 methomyl completely within 3 d by the cooperative metabolism. Methomyl was first converted to methomyl oxime and methylcarbamic acid by strain MDW-2, and the latter could be used as the carbon source for the growth of strain MDW-2. But methomyl oxime could not be sequentially degraded by strain MDW-2. However, it could be degraded and used as the carbon source by strain MDW-3. This article is protected by copyright. All rights reserved.