Molecular Monitoring of Gramonol Herbicide Biodegradation in Relation to Streptomyces scabies Isolates

The aim of this study was to test the effect of Streptomyces scabies on the degradation of Gramonol herbicide in order to reduce its residual toxicity. Four isolates of S. scabies (St1, St2, St3, and St4) showed different ability to degrade the gramonol in vitro and in soil. They varied in their potential ability to degrade Gramonol in vitro after 5 days incubation, and after 35 days post herbicidal treatment. S. scabies isolate St4 was the most active of the four isolates. To demonstrate this effect, PCR in DNA genome was used to detect dehalogenase gene in the 4 isolates and residual Gramonol was determined by GLC after 10, 20 and 30 days. The study showed the degradation rate of Gramonol increased with time and that less Gramonol residue was found in non sterile soil compared to sterile soil. However, Gramonol did not show an effect on the Streptomyces isolates growth. Therefore, Streptomyces scabies can be used to degrade Gramonol herbicide and reduce toxicity hazard to man.