Isolation and characterisation of a bacterial strain degrading the herbicide sulcotrione from an agricultural soil

Laboratoire de Chimie des Biomolécules et de l'Environnement, Université de Perpignan Via Domitia, Perpignan, France.
Pest Management Science (Impact Factor: 2.69). 03/2012; 68(3):340-7. DOI: 10.1002/ps.2263
Source: PubMed


The dissipation kinetics of the herbicide sulcotrione sprayed 4 times on a French soil was studied using a laboratory microcosm approach. An advanced cultivation-based method was then used to isolate the bacteria responsible for biotransformation of sulcotrione. Chromatographic methods were employed as complementary tools to define its metabolic pathway.
Soil microflora was able quickly to biotransform the herbicide (DT(50) ≈ 8 days). 2-Chloro-4-mesylbenzoic acid, one of its main metabolites, was clearly detected. However, no accelerated biodegradation process was observed. Eight pure sulcotrione-resistant strains were isolated, but only one (1OP) was capable of degrading this herbicide with a relatively high efficiency and to use it as a sole source of carbon and energy. In parallel, another sulcotrione-resistant strain (1TRANS) was shown to be incapable of degrading the herbicide. Amplified ribosomal restriction analysis (ARDRA) and repetitive extragenic palendromic PCR genomic (REP-PCR) fingerprinting of strains 1OP and 1TRANS gave indistinguishable profiles.
Sequencing and aligning analysis of 16S rDNA genes of each pure strain revealed identical sequences and a close phylogenetic relationship (99% sequence identity) to Pseudomonas putida. Such physiological and genetic properties of 1OP to metabolise sulcotrione were probably governed by mobile genetic elements in the genome of the bacteria.

Download full-text


Available from: Christophe Calvayrac, Apr 22, 2014
72 Reads
    • "1OP (Calvayrac et al. 2012). As previously suggested, this discrepancy might be caused by abiotic transformation of CHD or to β-diketone oxidation catalyzed by enzymatic C–C bound breaking (Calvayrac et al. 2012). CMBA and CHD degrading tests have been carried out in resting cell experiments showing that SR1 was unable to degrade these two metabolites. "
    [Show abstract] [Hide abstract]
    ABSTRACT: In this study, a bacterial strain able to use sulcotrione, a β-triketone herbicide, as sole source of carbon and energy was isolated from soil samples previously treated with this herbicide. Phylogenetic study based on16S rRNA gene sequence showed that the isolate has 100 % of similarity with several Bradyrhizobium and was accordingly designated as Bradyrhizobium sp. SR1. Plasmid profiling revealed the presence of a large plasmid (>50 kb) in SR1 not cured under nonselective conditions. Its transfer to Escherichia coli by electroporation failed to induce β-triketone degrading capacity, suggesting that degrading genes possibly located on this plasmid cannot be expressed in E. coli or that they are not plasmid borne. The evaluation of the SR1 ability to degrade various synthetic (mesotrione and tembotrione) and natural (leptospermone) triketones showed that this strain was also able to degrade mesotrione. Although SR1 was able to entirely dissipate both herbicides, degradation rate of sulcotrione was ten times higher than that of mesotrione, showing a greater affinity of degrading-enzyme system to sulcotrione. Degradation pathway of sulcotrione involved the formation of 2-chloro-4-mesylbenzoic acid (CMBA), previously identified in sulcotrione degradation, and of a new metabolite identified as hydroxy-sulcotrione. Mesotrione degradation pathway leads to the accumulation of 4-methylsulfonyl-2-nitrobenzoic acid (MNBA) and 2-amino-4 methylsulfonylbenzoic acid (AMBA), two well-known metabolites of this herbicide. Along with the dissipation of β-triketones, one could observe the decrease in 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibition, indicating that toxicity was due to parent molecules, and not to the formed metabolites. This is the first report of the isolation of bacterial strain able to transform two β-triketones.
    Environmental Science and Pollution Research 04/2015; DOI:10.1007/s11356-015-4544-1 · 2.83 Impact Factor
  • Source
    • "Sulcotrione degradation in the soil is influenced by biotic and/or abiotic factors [3]. Half-life ranges between 45 and 65 days in soil and is 8 days with microflora [2]. 1,3- Cyclohexanedione (CHD) and 2-chloro-4-mesylbenzoic acid (CMBA) are among the observed degradation compounds [10]. "
    [Show abstract] [Hide abstract]
    ABSTRACT: The cytotoxic effects of 2-chloro-4-mesylbenzoic acid (CMBA) and xanthene-1,9-dione-3,4-dihydro-6-methylsulphonyl (XDD), the two main photoproducts of sulcotrione, were investigated on Allium root meristematic cells at different concentrations. Degradation of sulcotrione was correlated to mitotic index decrease, together with increasing anomaly and c-mitosis frequencies. Mitotic index significantly decreased with increasing XDD and CMBA concentrations. Cell frequency with abnormal chromosomes increased with CMBA or XDD application rates. In contrast, CMBA induced a low micronucleus rate even for high concentrations while XDD increased the micronucleus ratio. C-mitoses, chromosomal aberrations due to an inactivation of the spindle, were enhanced by CMBA treatments but not by XDD. The photochemical degradation process of the pesticide can change the risk for the environment.
    Pesticide Biochemistry and Physiology 04/2015; DOI:10.1016/j.pestbp.2015.04.001 · 2.01 Impact Factor
  • Source
    • "The amount of b-triketone herbicides (sulcotrione or tembotrione ) and, concomitantly, the amount of the main metabolites of sulcotrione, CHD and CMBA (Calvayrac et al., 2012) remaining in the extra-cellular medium of bacterial cultures were measured by chromatographic methods during the time-course of the biodegradation process. Culture media extracts were prepared according to the procedure already described by the authors (Calvayrac et al., 2012 "
    [Show abstract] [Hide abstract]
    ABSTRACT: Pseudomonas sp. 1OP, previously isolated from a French agricultural soil, has been described as the first sulcotrione degrading bacteria. Different conditions of initial pH and herbicide concentration in liquid culture were tested to evaluate the growth performances of the isolate and its degrading capacity, with sulcotrione as the sole carbon and/or energy source. Maximal growth rate (μmax) was obtained under initial neutral conditions and with initial concentration of sulcotrione close to 180 μM, and was described, during the exponential phase, by a sigmoidal curve which could be easily fitted to the modified Gompertz equation. Complementary studies carried on the CMBA by-product and on another β-triketone herbicide showed the relative specificity of the strain against sulcotrione. The sulcotrione degrading phenotype of Pseudomonas sp.1OP was shown to be lost under non-selective conditions. Plasmid-Eckardt modified method, consecutively applied for plasmid profiling, showed that this strain carries one large plasmid (>12 kb) bearing putative genes involved in sulcotrione degradation, as demonstrated by curing experiment.
    International Biodeterioration & Biodegradation 07/2014; 91:104–110. DOI:10.1016/j.ibiod.2014.03.020 · 2.13 Impact Factor
Show more