Isolation and Characterization of Actinobacteria Involved in Biodegradation of Herbicide Sulfosulfuron (Apyros 75 WG)

Abstract

68 Actinobacteria strains were isolated and in vitro tested for their abilities to grow in the presence of sulfosulfuron (Apyros 75 WG) in starch casein agar medium supplemented at a concentration 10 fold of the recommended dose. The results revealed, that only 5 isolates showed abundant growth, 30 isolates moderate growth, 6 isolates a weak growth and 27 no growth. The ten most tolerant Actinobacteria were tested for their abilities to utilize sulfosulfuron (Apyros75 WG) herbicide as a sole source of carbon and energy. From these, only two strains (A1 and A12) showed an abundant growth on ISP9 agar medium containing sulfosulfuron (Apyros 75 WG) as a sole source of carbon and energy. One strain designated A1 tolerant and able to utilize sulfosulfuron (Apyros 75 WG) as sole source of carbon and energy, was selected for biodegradation assays of this herbicide, on ISP9 broth supplemented with sulfosulfuron (Apyros 75 WG) (100 mg L−1) as a sole source of carbon and energy. Strain A1 reduced the concentration of sulfosulfuron from 75 mg L−1 to 39.8, 2.7, 2.3 and 1.3 mg L−1, respectively, on first, fifth, tenth and fifteenth day of incubation, when it had degraded 98% of initial amount and had reached its highest cell mass of 0.074. Morphological characters and chemotaxonomic parameters indicated that strain A1 belong to the genus of Streptomyces.