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Applied and Environmental Microbiology, March 1999, p. 982-988, Vol. 65, No. 3
Laboratory of Microbial Ecology, University
of Ghent, B-9000 Ghent, Belgium
Received 27 July 1998/Accepted 8 December 1998
The effect of three phenyl urea herbicides (diuron, linuron, and
chlorotoluron) on soil microbial communities was studied by using
soil samples with a 10-year history of treatment. Denaturing gradient
gel electrophoresis (DGGE) was used for the analysis of 16S rRNA genes
(16S rDNA). The degree of similarity between the 16S rDNA profiles of
the communities was quantified by numerically analysing the DGGE band
patterns. Similarity dendrograms showed that the microbial community
structures of the herbicide-treated and nontreated soils were
significantly different. Moreover, the bacterial diversity seemed to
decrease in soils treated with urea herbicides, and sequence
determination of several DGGE fragments showed that the most affected
species in the soils treated with diuron and linuron belonged to an
uncultivated bacterial group. As well as the 16S rDNA fingerprints, the
substrate utilization patterns of the microbial communities were
compared. Principal-component analysis performed on BIOLOG data showed
that the functional abilities of the soil microbial
communities were altered by the application of the herbicides. In
addition, enrichment cultures of the different soils in medium with the
urea herbicides as the sole carbon and nitrogen source showed that
there was no difference between treated and nontreated soil in the rate
of transformation of diuron and chlorotoluron but that there was a
strong difference in the case of linuron. In the enrichment cultures
with linuron-treated soil, linuron disappeared completely after 1 week
whereas no significant transformation was observed in cultures
inoculated with nontreated soil even after 4 weeks. In conclusion, this
study showed that both the structure and metabolic potential of soil
microbial communities were clearly affected by a long-term application
of urea herbicides.
0099-2240/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Effect of Phenylurea Herbicides on Soil Microbial
Communities Estimated by Analysis of 16S rRNA Gene Fingerprints and
Community-Level Physiological Profiles
*
Corresponding author. Mailing address: Laboratory of
Microbial Ecology, University of Ghent, Coupure Links 653, B-9000
Ghent, Belgium. Phone: 32/9/264 59 12. Fax: 32/9/264 62 48. E-mail:
Eva.Top{at}rug.ac.be.
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