*4.2. Antagonistic Activity*

The studied isolates were verified for their biological activity against *E. coli* and *B. megaterium* using the cross-streak method as reported by Odumosu et al. [42]. Briefly, a single, small mass from a fresh culture (24 h) of each studied isolate was streaked in the center of a Petri dish containing King B (KB) nutrient media [46] and then incubated at 37 ◦C for 48 h. Successively, the plates were inoculated with the tested microorganisms by a single streak at a perpendicular close to the initial inoculum of each studied Actinomycetes isolate. All plates were incubated at 37 ◦C and the antagonistic activity was evaluated after 24 h. The bacterial antagonistic activity was recorded as follows: very high activity (+++); high activity (++); moderate activity (+); no activity (-). The most bioactive isolates were selected for molecular identification and further in vitro and in vivo biological assays.
