Biodegradation of the phenylurea herbicide isoproturon and its metabolites in agricultural soils

Sebastian R. Sørensen, Jens Aamand

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39 Citations (Scopus)

Abstract

Degradation of the phenylurea herbicide isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) and several phenylurea and aniline metabolites was studied in agricultural soils previously exposed to isoproturon. The potential for degradation of the demethylated metabolite 3-(4-isopropylphenyl)-1-methylurea in the soils was much higher compared to isoproturon. In the most active soil only 6% of added 14C-labelled isoproturon was mineralised to 14CO 2 within 20 days while in the same period 45% of added 14C-labelled 3-(4-isopropylphenyl)-1-methylurea was mineralized. This indicates that the initial N-demethylation may be a limiting step in the complete mineralization of isoproturon. Repeated addition of 3-(4-isopropylphenyl)-1-methylurea to the soil and further subculturing in mineral medium led to a highly enriched mixed bacterial culture with the ability to mineralize 3-(4-isopropylphenyl)-1-methylurea. The culture did not degrade either isoproturon or the didemethylated metabolite 3-(4-isopropylphenyl)-urea when provided as sole source of carbon and energy. The metabolite 4-isopropyl-aniline was also degraded and utilised for growth, thus indicating that 3-(4-isopropylphenyl)-1-methylurea is degraded by an initial cleavage of the methylurea-group followed by mineralization of the phenyl-moiety. Several attempts were made to isolate pure bacterial cultures degrading 3-(4-isopropylphenyl)-1-methylurea or 4-isopropyl-aniline, but they were not successful.

Original languageEnglish
Pages (from-to)69-77
Number of pages9
JournalBiodegradation
Volume12
Issue number1
DOIs
Publication statusPublished - Jan 2001

Keywords

  • Agricultural soils
  • Isoproturon
  • Metabolites
  • Mineralization
  • Mixed bacterial culture

Programme Area

  • Programme Area 2: Water Resources

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