Characterization of tribenuron-methyl resistant Actinobacteria strains
Résumé
Granstar® 75 DF, a sulfonylurea herbicide containing tribenuron-methyl (TBM) as active molecule, is worldwide used against a large number of annual dicotyledons. Its repeated and direct application could constitute a long-term environmental hazard that can be avoided by degradation potential of some soil microorganisms. In order to characterize four highly herbicide resistant Actinobacteria strains; SRK5, SRK13, SRK14 and SRK18, isolated from untreated and Granstar®treated soils, morphological, biochemical and phylogenetic analyses were conducted. The studied strains were different from each other, mainly by their morphological characteristics. The phylogenetic analysis, based on 16S rRNA genes sequencing, allowed the affiliation of all strains to Streptomyces genus and regrouped them into two clades. The first one including SRK13, SRK14 and SRK18 strains showed their link with four Streptomyces type strains; S. rochei, S. africanus, S. lavendulocolor and S. djakartensis. However, comparing morphological features cluster ed the three strains withS. rochei and excluded the other Streptomyces type species. SRK5 was separated from the other studied strains on a second clade and was closely related to Streptomyces tricolor