Résumé:
"Sulfonylurea herbicides are widely used on a wide range of crops to control weeds. Chevalier® OnePass
herbicide is a sulfonylurea herbicide intensively used on cereal crops in Algeria. No information is yet
available about the biodegradation of this herbicide or about its effect on the bacterial community of the soil.
In this study, we collected an untreated soil sample, and another sample was collected 1 month after
treatment with the herbicide. Using a high resolution melting DNA technique, we have shown that treatment
with Chevalier® OnePass herbicide only slightly changed the composition of the whole bacterial
community.
Two hundred fifty-nine macroscopically different clones were isolated from the untreated and treated soil
under both aerobic and microaerobic conditions. The strains were identified by sequencing a conserved
fragment of the 16S rRNA gene. The phylogenetic trees constructed using the sequencing results confirmed
that the bacterial populations were similar in the two soil samples.
Species belonging to the Lysinibacillus, Bacillus, Pseudomonas, and Paenibacillus genera were the most
abundant species found. Surprisingly, we found that among ten strains isolated from the treated soil, only six
were resistant to the herbicide.
Furthermore, bacterial overlay experiments showed that only one resistant strain (related to
Stenotrophomonas maltophilia) allowed all the sensitive strains tested to grow in the presence of the
herbicide. The other resistant strains allowed only certain sensitive strains to grow.
On the basis of these results, we propose that there must be several biodegradation pathways for this
sulfonylurea herbicide."
