title: Isolation from agricultural soil and characterization of a Sphingomonas sp. able to mineralize the phenylurea herbicide isoproturon.
abstract: A soil bacterium (designated strain SRS2) able to metabolize the phenylurea herbicide isoproturon, 3-(4-isopropylphenyl)-1,1-dimethylurea (IPU), was isolated from a previously IPU-treated agricultural soil. Based on a partial analysis of the 16S rRNA gene and the cellular fatty acids, the strain was identified as a Sphingomonas sp. within the alpha-subdivision of the proteobacteria. Strain SRS2 was able to mineralize IPU when provided as a source of carbon, nitrogen, and energy. Supplementing the medium with a mixture of amino acids considerably enhanced IPU mineralization. Mineralization of IPU was accompanied by transient accumulation of the metabolites 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, and 4-isopropyl-aniline identified by high-performance liquid chromatography analysis, thus indicating a metabolic pathway initiated by two successive N-demethylations, followed by cleavage of the urea side chain and finally by mineralization of the phenyl structure. Strain SRS2 also transformed the dimethylurea-substituted herbicides diuron and chlorotoluron, giving rise to as-yet-unidentified products. In addition, no degradation of the methoxy-methylurea-substituted herbicide linuron was observed. This report is the first characterization of a pure bacterial culture able to mineralize IPU.
authors.affiliation: Department of Geochemistry, Geological Survey of Denmark and Greenland, Copenhagen, Denmark.
authors.forename: S R
authors.initials: SR
authors.lastname: Sørensen
authors.forename: Z
authors.initials: Z
authors.lastname: Ronen
authors.forename: J
authors.initials: J
authors.lastname: Aamand
mesh_terms: D000383:Agriculture; D001431:Bacteriological Techniques; D001673:Biodegradation, Environmental; D003470:Culture Media; D006540:Herbicides / Q000378:metabolism*; D008782:Methylurea Compounds / Q000378:metabolism*; D010671:Phenylurea Compounds; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism*; D020578:Sphingomonas / Q000145:classification / Q000302:isolation & purification* / Q000378:metabolism
chemical_list: D003470:Culture Media; D006540:Herbicides; D008782:Methylurea Compounds; D010671:Phenylurea Compounds; D012989:Soil Pollutants; C028904:isoproturon