Isolation and identification of Gallant Super (Haloxyfop-Rmethyl)degrading bacteria in canola fields

Background and Aim : Herbicides are one of the most important and necessary inputs in thecropping systems of developed countries and its residues causes the environmental pollution.Biodegradation by microorganisms is considered as the novel method to reduce these risks. Theaim of this study was to isolate and identify bacteria degrading Haloxyfop-R-methyl in soilscontaminated with this herbicide, based on biochemical, morphological and molecularcharacteristics and to investigate the rate of degradation of Haloxyfop-R-methyl by selectedstrains.Methods : Topsoil containing organic matter was removed from canola fields in Selseleh cityusing sterile gloves, and then soil was sampled from a depth of ۰ to ۳۰ cm. For the initial isolationof soil bacteria, the nutrient agar medium containing a concentration of ۱۰% the herbicide wasused.Results : In carbon source substitution test using Standard Succinate Medium containing ۵% ofthe herbicide, only ۱۷ bacteria appeared. The isolates were placed in five groups based on thebiochemical tests including gram reaction, Xanthomonadin and fluorescent pigmentationproduction, oxidase, catalase, H۲s from cysteine, Levan production, Tween ۲۰ Hydrolysis Test,and oxidative/fermentative tests. For molecular diagnosis, five representative isolates wereselected and subjected to amplify ۱۶S rDNA gene using ۱۶s F and ۱۶sR primers and sequenced.Sequences were aligned and compared to the NCBI reference sequences.Conclusion : Based on biochemical and molecular tests, the isolates were identified as Acidovoraxsp, Acinetobacter calcoaceticus, Achromobacter sp., Stenotrophomonas rhizophila and Variovoraxparadoxus. The lowest Minimum Inhibitory Concentration(MIC) and Minimum BactericidalConcentration (MBC) were attributed to V. paradoxus, while the highest MIC and MBC belongingto A. calcoaceticus.

کلیدواژه ها:

Herbicide ، MBC ، MIC ،