Journal article
Enhanced mineralization of [U-14C]2,4-dichloropheeoxyacetic acid in soil from the rhizosphere of Trifolium pratense
Applied and Environmental Microbiology, Vol.70(8), pp.4766-4774
2004
Abstract
Enhanced biodegradation in the rhizosphere has been reported for many organic xenobiotic compounds, although the mechanisms are noi fully understood. The purpose of this study was to discover whether rhizosphere-enhanced biodegradation is due to selective enrichment of degraders through growth on compounds produced by rhizodeposition. We monitored the mineralization of [U-14C]2,4-dichlorophenoxyacetic acid (2,4-D) in rhizosphere soil with no history of herbicide application collected over a period of 0 to 116 days after sowing of Lolium perenne and Trifolium pratense. The relationships between the mineralization kinetics, the number of 2,4-D degraders, and the diversity of genes encoding 2,4-D/?-ketoglutarate diosygenase (tfdA) were investigated. The rhizosphere effect on [14C]2,4-D mineralization (50 ?g g-1) was shown to be plant species and plant age specific. In comparison with nonplanted soil, there were significant (P < 0.05) reductions in the lag phase and enhancements of the maximum mineralization rate for 25- and 60-day T. pratense soil but not for 116-day T. pratense rhizosphere soil or for L. perenne rhizosphere soil of any age. Numbers of 2,4-D degraders in planted and nonplanted soil were low (most probable number, <100 g -1) and were not related to plant species or age. Single-strand conformational polymorphism analysis showed that plant species had no impact on the diversity of ?-Proteobacteria tfdA-like genes, although an impact of 2,4-D application was recorded. Our results indicate that enhanced mineralization in T. pratense rhizosphere soil is not due to enrichment of 2,4-D-degrading microorganisms by rhizodeposits. We suggest an alternative mechanism in which one or more components of the rhizodeposits induce the 2,4-D pathway.
Details
- Title
- Enhanced mineralization of [U-14C]2,4-dichloropheeoxyacetic acid in soil from the rhizosphere of Trifolium pratense
- Authors
- L J Shaw (Author) - University of Kent, United KingdomRichard G Burns (Author) - University of Kent, United Kingdom
- Publication details
- Applied and Environmental Microbiology, Vol.70(8), pp.4766-4774
- Publisher
- American Society for Microbiology
- Date published
- 2004
- DOI
- 10.1128/AEM.70.8.4766-4774.2004
- ISSN
- 0099-2240
- Copyright note
- Copyright © 2004 American Society for Microbiology. Reproduced here in accordance with the publishers copyright policy.
- Organisation Unit
- University of the Sunshine Coast, Queensland; Office of the Deputy Vice-Chancellor (Research and Innovation)
- Language
- English
- Record Identifier
- 99449187302621
- Output Type
- Journal article
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- Collaboration types
- Domestic collaboration
- International collaboration
- Web Of Science research areas
- Biotechnology & Applied Microbiology
- Microbiology