Antibacterial and insecticidal activity of actinomycetes isolated from sandy soil of (Cairo-Egypt).

The present study was undertaken to screen antibacterial and insecticidal activities of crude extract of twenty actinomycetes isolates from desert soil samples collected from different locations of Cairo-Egypt. Isolate No. A11 was found to be the most active actinomycetes isolate against Gram positive, Gram negative bacteria and 2nd instar larvae of cotton leaf worm Spodoptera littoralis (Boisd.). The most active isolate was selected for further studies concerning their identification. Morphological, physiological and phylogenetic analysis (16S rRNA); in addition to biochemical studies and cultural characteristics as well as chemical analysis of the cell wall, were carried out for the isolate under study. Based on the phenotypic and genotypic accumulated characteristics of the selected isolate and recommended International Key’s of Bergey’s Manual for identification of actinomycetes, it was found that this isolate matched with Streptomyces bikiniensis and was given the name Streptomyces bikiniensisA11. The active metabolite of selected isolate was extracted by chloroform. Fraction No. 17 was the most active fraction against bacteria and insect species under study. The separation, purification and characterization of the active metabolite(s) were performed using thin layer chromatography. Based on the physicochemical studies for the purified compound; it was found that the purified compound may be belonged to Aminoglycosidic antibiotic.