Carbofuran is a common agricultural pesticide belonging to the N-methylcarbamate family. It is used to control soil dwelling and leaf feeding insects. It has a high mammalian toxicity due to acetylcholinesterase inhibition. The oral LD50 value of carbofuran in mice and other animals has been reported to vary from 2 to 9 mg/kg bodyweight. Since it is water soluble and mobile in soil environments, it is very likely to contaminate lakes and ground water, so a major exposure to it is by drinking contaminated water. Because of this, it is important to find out ways to biodegrade it.
Sphingomonas sp. strain SB5, can degrade carbofuran into carbofuran-7-phenol and methylamine, hydrolyze carbofuran-7-phenol to 3-(2-hydroxy-2-methylpropyl)benzene-1,2-diol (DP-1), and then degrade DP-1 into a red metabolite (DP-2). More study is needed to identify this red metabolite (Kim et al., 2004). Pseudomonas sp. 50432 is capable of hydroxylating carbofuran at the 4-position; further metabolites are unknown (Chaudhry et al., 2002). Carbofuran may also be hydroxylated at the 5 position by Novosphingobium sp. FND-3 and Rhodococcus TEI (Yan et al., 2006). Fungal degradation of carbofuran may occur via hydroxylation at the three position and oxidation to 3-ketocarbofuran (Salama et al., 1998).
The following is a text-format carbaryl pathway map. An organism which can initiate the pathway is 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 format.
Graphical map (9k) | Graphical map (5k) Carbofuran Carbofuran Carbofuran Carbofuran Carbofuran Novosphingobium sp. FND-3 Sphingomonas sp. Pseudomonas sp. 50432 Aspergillus niger Novosphingobium sp. FND-3 | Novosphingobium sp. FND-3 | Fusarium graminearum Rhodococcus TEI | Pseudomonas sp. 50432 | | | carbofuran | | | | | furanhydrolase | | carbofuran | carbofuran | carbofuran | carbofuran | | hydrolase | hydroxylase | 3-hydroxylase | 5-hydroxylase v | | | | 2-Hydroxy-3- v v v v (3-methylpropan-2-ol) Carbofuran- + Methylamine 4-Hydroxy- 3-Hydroxy- 5-Hydroxy- benzene-N-methyl- 7-phenol | carbofuran carbofuran carbofuran carbamate | | | | | | carbofuran- | | | 2-hydroxy-3- | | 7-phenol | v A | 3-hydroxycarbofuran (3-methylpropan-2-ol) | | hyrolase | | | dehydrogenase benzene-N-methyl- | | v | | carbamate | v to the v v hydrolase | 3-(2-hydroxy- Glyphosate CO2 3-Ketocarbofuran +----------> 2-methylpropyl) Pathway | benzene-1,2-diol | | v Methylamine | | | v to the Glyphosate Pathway
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