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In-field spatial variability in the degradation of the phenyl-urea herbicide isoproturon is the result of interactions between degradative Sphingomonas spp. and soil pH.
- Source :
-
Applied and environmental microbiology [Appl Environ Microbiol] 2003 Feb; Vol. 69 (2), pp. 827-34. - Publication Year :
- 2003
-
Abstract
- Substantial spatial variability in the degradation rate of the phenyl-urea herbicide isoproturon (IPU) [3-(4-isopropylphenyl)-1,1-dimethylurea] has been shown to occur within agricultural fields, with implications for the longevity of the compound in the soil, and its movement to ground- and surface water. The microbial mechanisms underlying such spatial variability in degradation rate were investigated at Deep Slade field in Warwickshire, United Kingdom. Most-probable-number analysis showed that rapid degradation of IPU was associated with proliferation of IPU-degrading organisms. Slow degradation of IPU was linked to either a delay in the proliferation of IPU-degrading organisms or apparent cometabolic degradation. Using enrichment techniques, an IPU-degrading bacterial culture (designated strain F35) was isolated from fast-degrading soil, and partial 16S rRNA sequencing placed it within the Sphingomonas group. Denaturing gradient gel electrophoresis (DGGE) of PCR-amplified bacterial community 16S rRNA revealed two bands that increased in intensity in soil during growth-linked metabolism of IPU, and sequencing of the excised bands showed high sequence homology to the Sphingomonas group. However, while F35 was not closely related to either DGGE band, one of the DGGE bands showed 100% partial 16S rRNA sequence homology to an IPU-degrading Sphingomonas sp. (strain SRS2) isolated from Deep Slade field in an earlier study. Experiments with strains SRS2 and F35 in soil and liquid culture showed that the isolates had a narrow pH optimum (7 to 7.5) for metabolism of IPU. The pH requirements of IPU-degrading strains of Sphingomonas spp. could largely account for the spatial variation of IPU degradation rates across the field.
- Subjects :
- Biodegradation, Environmental
Colony Count, Microbial
DNA, Bacterial analysis
DNA, Bacterial genetics
DNA, Ribosomal analysis
DNA, Ribosomal genetics
Electrophoresis methods
Hydrogen-Ion Concentration
Molecular Sequence Data
Phylogeny
RNA, Ribosomal, 16S genetics
Soil analysis
Sphingomonas genetics
Sphingomonas growth & development
Sphingomonas isolation & purification
United Kingdom
Herbicides metabolism
Methylurea Compounds metabolism
Phenylurea Compounds
Soil Microbiology
Sphingomonas metabolism
Subjects
Details
- Language :
- English
- ISSN :
- 0099-2240
- Volume :
- 69
- Issue :
- 2
- Database :
- MEDLINE
- Journal :
- Applied and environmental microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 12571001
- Full Text :
- https://doi.org/10.1128/AEM.69.2.827-834.2003