Sphingomonas sp. strain SB5 degrades carbofuran to a new metabolite by hydrolysis at the furanyl ring

Microorganisms capable of degrading carbofuran were isolated from soils and examined for the degradation of this pesticide at ring structure. An isolate that could degrade carbofuran and carbofuran-7-phenol was selected for further studies. The 16S rRNA analysis results showed that the isolate belongs to the genus of Sphingomonas, close to dioxin and dicamba degraders, and is named Sphingomonas sp. SB5. SB5 did not show any similarity of 16S rRNA to known carbofuran degraders. When time-course degradation of carbofuran by SB5 was examined by solvent extraction combined with liquid chromatographic analysis, almost complete disappearance of carbofuran was observed within 12 h, giving several accumulative metabolites. Bacterial cultures incubated with carbofuran-7-phenol suggested that the accumulated metabolites were derived from carbofuran-7-phenol. The control without SB5 and kanamycin-treated SB5 did not show any metabolite, suggesting a biological involvement in the degradation of carbofuran. GC/MS and LC/MS analyses identified 2-hydroxy-3-(3-methylpropan-2-ol) phenol as one of the accumulated metabolites, suggesting that the strain SB5 could degrade carbofuran-7-phenol by hydrolysis at the furanyl ring. This is the first report to identify 2-hydroxy-3-(3-methylpropan-2-ol) phenol as a new product derived biologically from carbofuran-7-phenol.