Monitoring Biodegradation of Gramonol Herbicide by Streptomyces scabies

Document Type : Original Article

Authors

1 Higher Institute for Agric., Shoubra El-Kheima, Cairo, Egypt.

2 Faculty of Agriculture and Veterinary, Al Azhar University, Gaza, Palestine.

3 Dept. of Microbiology, Fac. of Agric., Ain Shams Univ. Egypt.

4 Department of Life and Earth Sciences. Higher N,Djamene Institute For Training Teachers, Chad.

Abstract

The biodegradation behavior of pesticides on and in various edible plants was studied by many others. They concluded that the current levels of the pesticides in surface water and plants do not constitute an acute toxicity hazard to man and animals on a short-term basis, but as a result of their accumulation in the main body, it causes a hazard of long-term exposure.  Visual observation by light and electron microscopes of four Streptomyces spp. isolated from rhizosphere potato plants showed differentiation in mycelium and conidia spores as well as a variable diffusible pigment in a selective medium. The four Streptomyces spp. were identified as Streptomyces scabies by VITEK 2 system. The potential of granola herbicide degradation in relation to S. scabies isolates detected by polymerase chain reaction (PCR).  Four S. scabies isolates showed different potential abilities to degrade the gramonol in   Lab. and in soil in the course of 5 days of incubation and 35 days post herbicide treatment respectively.  It is clear that S. scabies isolates St4 was more active in gramonol degradation than the other isolates.  Dehalogenase gene was detected by PCR in DNA genome of 4 isolates.  It was found differences among isolates related to fragment density and size. Residual gramonol determined by GLC after 10, 20 and 30 days.  It was observed the degradation rate increased with increased time as well as a small amount of gramonol residue was observed in non-sterilized soil compared with sterilized soil in relation to increasing the count of total microorganisms.  On the other hand, the effect of gramonol on Streptomyces isolates growth was non-observed.

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